Biomedical subjects

R E Garner

Publications and source records attributed to R E Garner.

At least 19 recordsLinked to original sources

PubMed1996

Intravenous injection of Candida-derived mannan results in elevated tumor necrosis factor alpha levels in serum.

Intravenous injection of Candida albicans into mice produced elevated serum tumor necrosis factor alpha (TNF-alpha) levels. We hypothesized that immunostimulants released in vivo from C. albicans during fungal sepsis might contribute to the elevated levels of TNF-alpha in serum. We tested this hypothesis in mice with C. albicans mannan (CAM). Increased serum TNF-alpha levels were observed following intravenous and intraperitoneal injections of CAM. Injection of CAM into mice resulted in increased serum TNF-alpha concentrations that reached 1,200 pg/ml of blood, compared with 2,400 microg/ml of blood following injection of 10 microg of endotoxin. The response to CAM was concentration dependent, requiring a minimum dose of 20 microg of CAM per g of body weight. Sera from mice were tested 30, 60, 90, and 120 min after intravenous injections with CAM. TNF-alpha concentrations were minimal 30 and 120 min after intravenous injection and maximal 60 and 90 min after CAM injection. The relative distribution of CAM in vivo in decreasing order was determined to be as follows: blood > liver > lung > spleen, 90 min following injection of a single 5-mg dose of CAM. CAM was confirmed as the stimulating substance by utilizing anti-CAM antibodies in vivo to block the response. Rabbit anti-mannan antibodies administered by intraperitoneal injection 24 h before CAM injection significantly suppressed (P < 0.05) the accumulation of TNF-alpha in the sera. Dexamethasone administered to mice before intravenous injection of mannan significantly reduced (40 to 90% reduction; P < 0.05) the concentrations of TNF-alpha in the sera of treated mice. Thus, when in vivo CAM clearance mechanisms are exceeded, sufficient CAM may become available to stimulate TNF-alpha production, making CAM an important part of pathogenesis in Candida sepsis.

Animals↗

PubMed1994

Secretion of TNF-alpha by alveolar macrophages in response to Candida albicans mannan.

Resident alveolar macrophages (AM phi) were tested for their ability to respond to Candida albicans mannan. AM phi were found to produce tumor necrosis factor alpha (TNF-alpha) in vitro in response to mannan stimulation. TNF-alpha secretion was measured using ELISA and L929B cellular cytotoxicity assays. Cytotoxicity was neutralized in parallel L929B cell cultures by the addition of rabbit anti-TNF-alpha antibody. Mannan preparations were found to be free of contaminating LPS by Limulus assay. When AM phi were cultivated for 18 h at 37 degrees C, 67 micrograms of mannan stimulated the secretion of approximately 207 U/ml of TNF-alpha. By comparison, AM phi treated with 6.7 micrograms of LPS secreted approximately 257 U/ml of TNF-alpha. Optimal TNF-alpha production occurred between 9 and 18 h after mannan stimulation. Disparate mechanisms for stimulation of TNF-alpha secretion were suggested by differential sugar blockade of LPS- and mannan-induced TNF-alpha secretion. The addition of 2% D-mannose or 2% alpha-methyl-D-mannoside to AM phi cultures blocked mannan- but not LPS-stimulated TNF-alpha secretion. Furthermore, the addition of rabbit anti-mannan antibody to mannan-coated plastic culture dishes prevented TNF-alpha secretion by the mannan-sensitive RAW 264.7 cell line. Moreover, the data suggest that C. albicans mannan stimulated AM phi to secrete TNF-alpha by an LPS-independent receptor mechanism which may also function as a mannose receptor.

Animals↗

PubMed1994

Lack of effect of Candida albicans mannan on development of protective immune responses in experimental murine candidiasis.

Candida albicans mannoprotein (MAN) administered to mice before or during immunization with viable C. albicans downregulates MAN-specific delayed hypersensitivity. In the experiments reported here we determined the effect of MAN downregulation on protective immunity in minimally immunized mice, i.e., mice exposed to C. albicans either intradermally or intragastrically, and in maximally immunized mice, i.e., mice immunized by a combination of intradermal and intragastric exposure, in experimental systemic candidiasis. MAN suppression did not induce statistically significant alterations in the protective responses in experimental candidiasis, although 8 of 12 groups of mice treated with MAN had fewer CFU of C. albicans in their kidneys than their non-MAN-treated counterparts. The results emphasize the lack of correlation of delayed hypersensitivity with protection in candidiasis and suggest that MAN may contain epitopes involved in the protective response.

Animals↗

PubMed1992

Arg-Gly-Asp (RGD) peptides alter hepatic killing of Candida albicans in the isolated perfused mouse liver model.

The isolated perfused mouse liver model was used to study the effect of Arg-Gly-Asp (RGD)-containing peptides on hepatic trapping and killing of Candida albicans. After extensive washing, 10(6) C. albicans CFU were infused into mouse livers. At the time of recovery, 63% +/- 2% (mean +/- standard error of the mean) of the infused C. albicans CFU were recovered from the liver and 14% +/- 1% were recovered from the effluent for a total recovery of 77% +/- 2%. This indicates that 86% +/- 9% of the original inoculum was trapped by the liver and that 23% +/- 2% was killed within the liver. Prior to their infusion into livers, 10(7) CFU of C. albicans were incubated at 37 degrees C for 30 min in the presence of various RGD peptides (0.1 mg/ml). Repeatedly, more than 90% of the infused RGD-treated C. albicans was trapped by the perfused liver. In comparison with the 23% killing rate observed in control livers, perfused livers killed approximately 40 to 50% of the infused C. albicans treated either with fibronectin, PepTite 2000, RGD, or RGDS. Hepatic killing of C. albicans treated with PepTite 2000 or fibronectin was dose dependent. Treatment of C. albicans with GRGDTP, GRGDSP, GRADSP, or GRGESP did not alter the ability of the perfused liver to kill C. albicans, suggesting that a degree of specificity for RGD peptides is associated with an increased ability of liver to kill RGD-treated C. albicans. Together, the data suggest that RGD peptides bind to a receptor on the surface of C. albicans, thereby increasing hepatic, and presumably Kupffer cell, killing of C. albicans. Natural or synthetic RGD peptides may serve as opsonins promoting C. albicans killing by Kupffer cells.

Amino Acid Sequence↗

PubMed1992

Effect of lectins on hepatic clearance and killing of Candida albicans by the isolated perfused mouse liver.

The isolated perfused mouse liver model was used to study the effects of various lectins on hepatic trapping and killing of Candida albicans. After mouse livers were washed with 20 to 30 ml of perfusion buffer, 10(6) C. albicans CFU were infused into the livers. At the time of recovery, 63% +/- 2% (mean +/- standard error of the mean) of the infused C. albicans CFU were recovered from the liver and 14% +/- 1% were recovered from the effluent for a total recovery of 77% +/- 2%. This indicated that 86% +/- 9% of the original inoculum was trapped by the liver and that 23% +/- 2% was killed within the liver. When included in both preperfusion and postperfusion buffers (0.2 mg of lectin per ml), Ulex europeaus lectin (binding specificity for fucose) decreased hepatic trapping of C. albicans by 37% and eluted trapped C. albicans from the liver only when included in postperfusion buffer. By comparison, treatment of C. albicans with U. europeaus lectin before infusion had no effect on the trapping or killing of yeast cells. When Lens culinaris lectin (binding specificity for mannose) was included in the perfusion buffers, hepatic killing of C. albicans increased by 16% with no significant effect on hepatic killing when yeast cells were treated with L. culinaris lectin before infusion. Forty to 55% of the infused C. albicans were killed when concanavalin A (binding specificities for mannose and glucose), Glycine max (binding specificity for N-acetylgalactosamine), or Arachis hypogea (binding specificity for galactose) lectin was included in the perfusion buffer or when yeast cells were treated with these lectins before their infusion. When C. albicans was treated with concanavalin A at a concentration of less than 0.02 mg/ml, hepatic killing of yeast cells was not significantly increased. The data suggest that a fucose-containing receptor on the surface of either sinusoidal endothelial cells or Kupffer cells is involved in the trapping of C. albicans by the perfused mouse liver. Moreover, lectins with binding specificities for mannose, N-acetylgalactosamine, and galactose increased hepatic killing of C. albicans.

Animals↗

PubMed1992

Effect of in vivo administration of recombinant murine gamma interferon on in vitro lymphoproliferative responses following immunization with Candida albicans.

The effect of in vivo administration of recombinant murine gamma interferon (rMuIFN-gamma) on in vitro proliferation of lymphocytes to Candida antigens and lectins was examined in naive CBA/J mice and in similar mice colonized with Candida albicans by intragastric (i.g.) intubation and/or inoculated intradermally (i.d.) with the fungus. Lymph node lymphocyte and splenic lymphocyte (splenocyte) responses to soluble cytoplasmic substances derived from C. albicans varied with the route of inoculation of the fungus, the sex of the animal, and the presence or absence of rMuIFN-gamma treatment. In the absence of rMuIFN-gamma treatment, lymphoid cells from lymph nodes draining the site of the i.d. lesion responded well to soluble cytoplasmic substances. Colonization of the gut of female mice with C. albicans either had no effect or promoted better lymph node responses when such animals were also challenged i.d., whereas gut colonization of males followed by i.d. challenge appeared to have a suppressive influence on the level of proliferation in response to antigens in vitro. Antigen-specific splenocyte responses could be detected as well, and they were best in animals inoculated i.g.-i.d. or i.d. only. With the exception of lymph node lymphocytes from male mice, treatment of infected animals, regardless of the route of infection, with rMuIFN-gamma frequently resulted in lowered responses to antigens when comparable treatment groups were examined. With respect to mitogen stimulation, infection with C. albicans, especially i.g. or i.g.-i.d., resulted in a population of lymph node lymphocytes with lower-than-normal responses to concanavalin A but higher-than-normal responses to lipopolysaccharide (LPS). Splenocyte responses to mitogens were not altered as dramatically as the responses of lymph node lymphocytes, but splenocytes from female mice had a suppressed response regardless of the route of exposure to C. albicans, and those from mice which were maximally stimulated with C. albicans, i.e., inoculated i.g.-i.d., also had a suppressed response to concanavalin A. Treatment with rMuIFN-gamma either had no effect on the subsequent splenocyte responses or boosted subnormal mitogen responses toward the normal range. Collectively, these data illustrate that exposure to both C. albicans and rMuIFN-gamma influenced the responses to mitogen and C. albicans antigen of lymph node lymphocyte and splenocyte populations, as detected in vitro by lymphoproliferation. Treatment with rMuIFN-gamma often resulted in increased responsiveness to a B cell mitogen, LPS, and decreased responsiveness to a C. albicans antigen.

Animals↗

PubMed1992

Murine Pneumocystis carinii adherence to vertical monolayers of cultured mink lung cells (MiCl1).

We describe a method for adherence and culture of murine Pneumocystis carinii in mink lung cells (MiCl1) grown on vertical supports. The vertical cultures were infected with P. carinii; the surrounding medium and inoculum were stirred to ensure circulation and contact with MiCl1 cells. When compared with conventional horizontal culture, the vertical method offers a more suitable system for assessing P. carinii adherence. This approach has proved suitable for quantitative evaluation of P. carinii adherence to MiCl1 cells in the presence of inhibitors.

Animals↗

PubMed1991

Immunocytochemical labeling of chitin in the cell walls of zoopathogenic fungi.

Chitin is a complex polysaccharide composed of repeating units of beta-1,4-N-acetyl-D-glucosamine. It is found in many invertebrates, in some algae, in the cyst form of several protozoans and in the cell walls of most fungi. Chitin, however, is not expressed in vertebrate tissues. We used a polyclonal rabbit antiserum against macromolecular chitin to label and stain by immunoperoxidase technique in formalin-fixed, paraffin-embedded tissues a variety of zoopathogenic fungi. The antiserum bound to the cell walls of the microorganisms, but not to (mammalian) host tissue elements.

Cell Wall↗

PubMed1990

Immunocytochemical detection of chitin in Pneumocystis carinii.

Polyclonal antisera against chitin and chitin oligomers were used to stain Pneumocystis carinii by the immunoperoxidase technique in Formalin-fixed, paraffin-embedded sections of four human lung biopsies and in alcohol-fixed, paraffin-embedded cell blocks of two bronchioloalveolar lavage specimens from infected human patients. In all cases, the antisera bound P. carinii but did not bind the host tissue elements. Moreover, the antisera bound not only to the cyst forms of P. carinii but also to the intracystic bodies and to the trophic forms. Preadsorption of the anti-chitin antiserum with purified chitin abolished all staining of P. carinii. Our results indicate that P. carinii produces chitin at more than one stage of its life cycle in the infected human host.

Animals↗

PubMed1990

Characterization of Candida albicans mannan-induced, mannan-specific delayed hypersensitivity suppressor cells.

We have shown previously that CBA/J mice immunized with Candida albicans developed delayed hypersensitivity (DH) demonstrable with mannan (MAN) extracted from the same organism and that the intravenous (i.v.) injection of MAN prior to or during the immunization phase resulted in the suppression of the MAN-specific DH response. In this study, we demonstrate that MAN-induced suppression of DH is a T-lymphocyte-mediated phenomenon. Suppressor cells induced in vivo by the i.v. injection of MAN into naive mice 1 to 7 days prior to harvest were passaged through nylon wool, treated with various surface-specific antibodies and complement, and then injected i.v. into immunized syngeneic recipients. Enrichment of splenic T cells by passage over nylon wool and transfer of the nylon-wool-nonadherent populations to immunized recipient mice suppressed DH in a dose-dependent manner. Depletion of Thy+ or Lyt-2+ cells from nylon-wool-nonadherent populations regularly ablated the ability of such suspensions to transfer suppression. Treatment of the same transfer suspensions with anti-Lyt-1 had variable effects, suggesting that the surface density of the Lyt-1 antigen was not as constant from population to population as was the Lyt-2 antigen. In addition, C. albicans MAN-induced suppressor cells were able to suppress DH demonstrable with Candida tropicalis MAN in animals immunized with C. tropicalis. Suppression of DH by MAN in this model, therefore, is mediated by Thy+ Lyt-2+ lymphocytes.

Animals↗

PubMed1990

Altered hepatic clearance and killing of Candida albicans in the isolated perfused mouse liver model.

The adherence of Candida albicans was studied in situ by using the perfused mouse liver model. After exhaustive washing, 10(6) C. albicans were infused into mouse livers. At the time of recovery, 62 +/- 5% (mean +/- standard error of the mean) of the infused C. albicans were recovered from the liver and 14 +/- 3% were recovered from the effluent for a total recovery of 76 +/- 4%. This indicates that 86 +/- 3% of the original inoculum was trapped by the liver and that 24 +/- 4% was killed within the liver. Chemical pretreatment of C. albicans with 8 M urea, 12 mM dithiothreitol, 2% beta-mercaptoethanol, 1% sodium dodecyl sulfate, 10% Triton X-100, or 3 M potassium chloride or enzyme pretreatment with alpha-mannosidase, alpha-chymotrypsin, subtilisin, beta-N-acetyl-glucosaminidase, pronase, trypsin, papain, or lipase did not alter adherence of C. albicans to hepatic tissue. By contrast, pepsin pretreatment significantly decreased hepatic trapping. Simultaneous perfusion with either 100 mg of C. albicans glycoprotein per liter or 100 mg of C. albicans mannan per liter also decreased trapping. Furthermore, both substances eluted previously trapped C. albicans from hepatic tissue. Chemical pretreatment with 8 M urea, 12 mM dithiothreitol, or 3 M KCI or enzymatic pretreatment with alpha-mannosidase, subtilisin, alpha-chymotrypsin, or papain increased killing of C. albicans three- to fivefold within hepatic tissue. The data suggest that mannose-containing structures on the surface of C. albicans, for example. mannans or glucomannoproteins, mediate adherence of C. albicans within the liver. Indirectly, chemical and enzymatic pretreatment renders C. albicans more susceptible to hepatic killing.

Animals↗

PubMed1989

Mannan as an antigen in cell-mediated immunity (CMI) assays and as a modulator of mannan-specific CMI.

Mannan (MAN) extracted from Candida albicans 20A was investigated for its potential as an antigen in the detection of cell-mediated immunity (CMI) in vivo and in vitro and for its ability to modulate CMI when administered intravenously (i.v.). CBA/J mice were either immunized as adults by the cutaneous inoculation of 10(6) viable blastoconidia or colonized as infants (primed) and then boosted cutaneously as adults. When immunized animals were footpad tested with MAN, highly significant delayed-type hypersensitivity (DH) responses were detected. The DH responses to MAN were of a greater magnitude than those noted with the same quantity of cell wall glycoprotein (GP), an ethylenediamine extract of the cell wall which contains both glucan and MAN. In contrast, GP was a better antigen for the detection of CMI responses in an in vitro lymphoproliferative assay with either spleen or lymph node cell suspensions. Mice treated with MAN i.v. prior to the initiation of immunization or between priming and secondary inoculations developed significantly suppressed DH reactions when tested with either MAN or GP. The lowest effective dose of MAN was 250 micrograms, maximum suppression occurred with 500 micrograms, and either dose given 1 week prior to immunization was suppressive. The suppression by MAN was specific for MAN or the MAN-containing GP. Responses to another unrelated candidal antigen, a membrane extract designated BEX, were relatively unaffected. MAN, therefore, was an effective antigen for the detection of CMI in vivo, and its administration i.v. created what appeared to be a MAN-specific suppression since it could be detected with both MAN and a MAN-containing extract from the cell wall. Caution must be exercised in the interpretation of these data, however, since the protein component of each of these extracts has not been characterized with respect to its potential role in the phenomena observed.

Animals↗

PubMed1989

In vivo immune responses to Candida albicans modified by treatment with recombinant murine gamma interferon.

The immunologic effects of in vivo administration of recombinant murine gamma interferon (rMuIFN-gamma) were determined in a murine model of candidiasis. Naive mice were given graded doses of rMuIFN-gamma and then challenged intravenously with Candida albicans. Increased morbidity and mortality were noted in four different strains of mice, viz., BALB/c, A/J, Swiss Webster, and CBA/J, providing the mice had not been immunized with C. albicans before challenge. Quantitative culture of selected organs of Swiss Webster and CBA/J mice surviving treatment with rMuIFN-gamma revealed elevated numbers of C. albicans cells, particularly in the kidneys, but also in the liver, lungs, and spleen. The lungs, livers, and spleen of female CBA/J mice were more protected from increased multiplication of the fungus than were those of males of the same species or female Swiss Webster mice. On the basis of these initial findings, the effect of treatment with 5,000 U of rMuIFN-gamma on immune responses in a gastrointestinal model of candidiasis was determined. CBA/J mice that had been colonized with C. albicans as infants were boosted with a cutaneous inoculation of the fungus when 6 to 10 weeks old; development of delayed hypersensitivity (DH), antibodies, and protective responses was assayed at intervals thereafter. Daily treatment with rMuIFN-gamma (beginning 1 day before cutaneous inoculation) suppressed weak immune responses but had little effect on responses which were strong. For example, DH and anti-C. albicans antibody production were suppressed in animals colonized with C. albicans but not boosted by cutaneous inoculation, and DH was suppressed in uncolonized animals that had been inoculated once cutaneously with the fungus as well. There was no rMuIFN-gamma-induced suppressive effect of DH in mice which had been stimulated maximally with C. albicans, i.e., colonized animals that had been boosted cutaneously with the organisms. Collectively, these data indicate that naive mice or mice with minimal levels of anti-C. albicans sensitivity, females somewhat more so than males, were sensitive to suppressive effects of in vivo treatment with rMuIFN-gamma when challenged with C. albicans. In contrast, under conditions similar to those of humans, in whom underlying immunity to C. albicans is usually present, suppression of host responses to C. albicans was not observed in immunized mice in response to treatment with rMuIFN-gamma.

Animals↗

PubMed1989

Immunomodulation in response to Candida.

Candidiasis may either precede or follow severe modulations in the immune system of the host. The focus of this review has been to survey the data and current interpretations for potential factors responsible for these events of immunomodulation. The mere fact that Candida infections persist is evidence of some underlying abnormality, often associated with, but not exclusively restricted to, the cell-mediated immune system. In some instances, however, the cause and effect relationship is not clear, i.e., did infection with Candida initiate the immunosuppression, or did the underlying condition result in immunosuppression allowing for Candida to initiate disease? It is possible, however, that candidal infections may begin during minor immunosuppressive events, e.g., stress, pregnancy, or selected other primary infections, but then persist beyond these events because of an intrinsic or innate immunomodulatory defect. Under such circumstances, the initial imbalance of immune function should be corrected by normal homeostatic mechanisms, unless persistent colonization with Candida perpetuates the imbalance through the production or release of immunomodulatory factors. One important target for research in this area, then, is the identification and purification of immunomodulatory factors produced or released during disease. To date, only preliminary data are available showing that the immunoregulatory potential of Candida resides in various candidal extracts, especially in the cell wall. Although the relevance of the data gathered in the experimental models might initially appear questionable, the fact that mannan, or molecules containing mannan, are known to circulate during disease (Weiner and Yount, 1976; Kerkering et al., 1979; Lehmann and Reiss, 1980) lends credence to the hypothesis. A second important target for future research is the identification of the cellular target within the immune system that responds to the Candida-derived immunomodulators. The success of these studies may well depend upon the degree of purification of the responsible factors. In fact, much of the variability observed to date in modulatory events may result from the heterogeneity of the modulator, including the possibility that antagonistic or synergistic interactions of the individual components occur. The variability observed in certain clinical settings could result from basic flaws in the normal immunoregulatory pathways in the host also, and if a link could be established between the basic flaws, the candidal extracts, and the target cell of the candidal extracts, it may be possible to manipulate the system through immunotherapy. Finally, the characterization of the candidal substances may provide yet another clinical tool for use as an immunomodulator in such disorders as cancer, inheritable immunodeficiencies, and AIDS.

Animals↗

PubMed1988

Nonspecific and Candida-specific immune responses in mice suppressed by chronic administration of anti-mu.

CBA/J mice were immunosuppressed by repeated administration of goat antibody specific for mu chain of immunoglobulin M (IgM) and tested for nonspecific and Candida albicans-specific immune responses. Immunosuppression was demonstrated by a dramatic reduction in the number of antibody-forming cells in the spleens of anti-mu-treated mice when immunized with sheep erythrocytes, by greatly reduced in vitro responsiveness of both spleen and lymph node lymphocytes from anti-mu-treated mice to lipopolysaccharide, and by a large reduction in the number of splenic IgM-positive cells. T cell function, on the other hand, appeared to be relatively unaltered in anti-mu-treated animals, in the cytotoxic T lymphocyte activity against an allogeneic target was similar in splenocyte cultures from anti-mu- and mock-treated animals, and splenic and lymph node lymphocytes proliferated in response to concanavalin A in a lymphocyte stimulation assay. Moreover, Candida-specific delayed hypersensitivity to two different Candida antigens, one cell wall-derived (GP) and the other cell membrane-derived (BEX), was of comparable intensity in immunosuppressed and normal animals. When anti-mu- and mock-treated mice were immunized by the cutaneous inoculation of viable C. albicans blastospores and then challenged intravenously to assess the development of protective immunity, only mock-treated animals, male and female, had significant (p less than or equal to 0.05) protective responses demonstrable by reduction in the number of colony-forming units cultured from their kidneys 28 days after intravenous challenge. If consideration was given to the number of animals which had cleared Candida completely from the kidney, however, there appeared to be protective responses operative in the female anti-mu-treated animals as well. Neither anti-mu-treated males nor females, when immunized and challenged with C. albicans, produced Candida-specific antibody detectable by counterimmunoelectrophoresis, whereas all immunized and challenged mock-treated animals produced antibody. The data are consistent with the hypothesis that anti-mu treatment has little effect on multiple cellular immune functions, including those specific for C. albicans, and the combination of antibody, cell-mediated immunity and innate defenses are responsible for solid systemic defense against the fungus.

Animals↗

PubMed1987

Prostaglandin E2 production by Mac-2+ macrophages: tumor-induced population shift.

Tumor growth induced a shift in the phenotype of macrophages (M luminal diameter) responsible for factor-mediated suppression of allogeneic mixed lymphocyte reactions (MLR), and the suppression by tumor-bearing host (TBH) Mac-2+ M luminal diameter was in part due to production of prostaglandin E2 (PGE2). Thioglycollate-elicited peritoneal M luminal diameter from normal and TBH BALB/c mice were modulated with anti-Mac-1, -2, or -3 monoclonal antibodies (mAb) or depleted with mAb plus complement and cultured in the presence or absence of indomethacin. Culture supernatants derived from mAb plus complement-depleted M luminal diameter were added to the MLR at time of initiation and showed that the suppressor phenotype shifted from Mac-3+ in the normal host to Mac-2+ in the TBH. Mac-1+ M luminal diameter also appeared to be involved in suppression by normal host, but not TBH, M luminal diameter. Loss of MLR suppression (increase in MLR reactivity) correlated with an increase in protein content of the culture supernatants. In an effort to explain both this relationship and the mechanism of MLR suppression, PGE2 levels of culture supernatants were determined by radioimmunoassay. Mac-1+ M luminal diameter were involved in the regulation of PGE2 production in normal hosts, as both activation and depletion caused an increase in PGE2 production. Depletion caused a more dramatic increase in PGE2 production than did activation, suggesting that Mac-1+ M luminal diameter had a dampening effect on PGE2 production. In contrast, no Mac-1+ M luminal diameter-mediated regulatory function occurred in the TBH. Mac-3+ M luminal diameter were involved in the regulation of PGE2 production in both normal and TBH. Mac-2+ M luminal diameter were the primary producers of PGE2 in the TBH, but not in the normal host, as their depletion in the TBH caused a significant loss of PGE2 production. Thus, immunosuppression in the TBH was at least partly due to the inability of Mac-1+ and/or Mac-3+ M luminal diameter to control production of PGE2 by Mac-2+ M luminal diameter.

Animals↗

PubMed1987

Shifts in macrophage (M phi) surface phenotypes during tumor growth: association of Mac-2+ and Mac-3+ M phi with immunosuppressive activity.

Rat anti-mouse monoclonal antibodies (mAb), anti-Mac-1, -2, and -3, directed against macrophage (M phi) glycoprotein surface antigens, were used to demonstrate a tumor-induced shift in peritoneal M phi subpopulations. This study of the tumor-induced shift was approached in two steps. First, to show that separate phenotypic M phi subpopulations existed and second, to show that a shift in these populations was involved in immunosuppression of the host during tumor growth. Endogenous peroxidase activity was examined among normal and tumor-bearing host (TBH) M phi. A significant increase in the number of peroxidase-positive M phi occurred during tumor growth. Indirect immunofluorescence showed a decrease in Mac-2+ cells and an increase in Mac-3+ cells in TBH M phi populations. When the mAb, anti-Mac-1,-2, and -3 were used in the presence of complement (C), they were cytotoxic for M phi and showed differential depletion of normal and TBH M phi. Peroxidase-positive TBH M phi were susceptible to C-mediated lysis by anti-Mac-1 and -3 but not by anti-Mac-2, whereas no direct relationship was observed among normal host M phi. To demonstrate differences between normal and TBH M phi subpopulations, soluble inhibitory factors were examined from mAb plus C-modified M phi populations. Anti-Mac plus C-treated normal and TBH M phi produced supernatants with different regulatory capabilities as assessed in the mixed-lymphocyte reaction (MLR). Anti-Mac-2 plus C treatment significantly reduced the ability of TBH M phi to produce a soluble suppressor(s) but did not alter normal host M phi-derived suppressor production. In contrast, anti-Mac-1 and -3 plus C treatment of normal host M phi significantly reduced suppressor production. In the TBH, however, anti-Mac-1 plus C had no effect, while anti-Mac-3 plus C had only a limited reduction as compared to the normal host. Determination of levels of prostaglandin E2 (PGE2) in M phi supernatants showed that normal host Mac-1+ M phi were involved in down regulation of PGE2 production. This control was missing in the TBH M phi. Mac-2+ M phi were the apparent producers of PGE2 which accounts for the factor-mediated MLR suppression attributed to TBH Mac-2+ M phi. Collectively, these data suggest that tumor-induced aberrations in immunoregulation can in part be attributed to differences in anti-Mac mAb-defined M phi subpopulations.

Animals↗

PubMed1987

Enhancement of non-Candida antibody responses by Candida albicans cell wall glycoprotein.

Two cell wall glycoprotein extracts from Candida albicans (glycoprotein [GP] and peptidoglucomannan [PGM]) were tested for their influence on antibody responses to type III pneumococcal polysaccharide and sheep erythrocytes. GP was isolated from lipid-extracted cell walls with ethylenediamine, whereas PGM was extracted with dilute sodium hydroxide. Both glycoproteins increased the number of antibody-producing plaque-forming cells in the spleens of mice immunized with type III polysaccharide or sheep erythrocytes, although PGM appeared to be about 10 times more effective. PGM could be administered up to 3 days prior to immunization with sheep erythrocytes to elicit enhancement; it did not have to be administered by the same route as the immunogen to cause significant enhancement. Enhancement did not appear to be the result of a direct mitogenic effect of GP and PGM on lymphocytes, nor did these glycoproteins appear to stimulate the production of B-cell growth factors or interleukin 2.

Adjuvants, Immunologic↗