Biomedical subjects

W H Boom

Publications and source records attributed to W H Boom.

At least 55 records · Page 3Linked to original sources

PubMed1993

Brugia malayi: acquired resistance to microfilariae in BALB/c mice correlates with local Th2 responses.

The role of specific Th subsets in the regulation of acquired resistance to the filarial parasite Brugia malayi is not known. We examined pathologic and cytokine responses in filarial antigen-sensitized BALB/c mice inoculated intraperitoneally with live microfilariae. Animals immunized three times with soluble microfilarial antigen demonstrated accelerated clearance of live parasites (12 +/- 5% of parasites recovered from the peritoneal cavity 4 days after inoculation vs 57 +/- 6% in controls, P < 0.001). Elimination of microfilariae by immunized mice was associated with local eosinophilia (1.5 x 10(7) eosinophils/ml peritoneal wash fluid compared with 2 x 10(5) eosinophils/ml in unimmunized animals), development of local eosinophil-containing granulomas, and elevated serum IgE levels (7.0 +/- 1.4 vs 2.1 +/- 0.9 micrograms/ml in controls, P < 0.01). CD4+ cells from the site of parasite challenge produced Th2-associated cytokines exclusively (IL-4 and IL-5, not IFN-gamma and IL-2) in response to Brugia antigen, whereas spleen and lymph node cells produced both Th1- and Th2-associated cytokines. Mice immunized a single time with microfilarial antigen did not clear parasites in this time, and peritoneal exudate cells from these animals produced IFN-gamma but not IL-5. These results indicate that acquired resistance to B. malayi microfilariae in mice is associated with induction of a Th2 and not a Th1 response at the site of parasite elimination.

Animals↗

PubMed1993

Screening of a cosmid library of Mycobacterium bovis BCG in Mycobacterium smegmatis for novel T-cell stimulatory antigens.

We have developed a novel method for screening a Mycobacterium bovis (BCG) cosmid library in Mycobacterium smegmatis for the detection of immunostimulatory T-cell antigens (Ag). Distinctive protein banding patterns were demonstrated in culture filtrates of three of 30 recombinant M. smegmatis clones: pBCCS13 (41 and 73 kDa); pBCCS221 (30, 50 and 68 kDa); pBCCS223 (100 kDa). Western immunoblots indicated that monoclonal antibodies (mAb) directed to the previously characterized 19-, 30-, 38-, 65- and 71-kDa mycobacterial Ag were not reactive with the distinctive recombinant proteins. Furthermore, T-cell Western blots demonstrated that fractions containing the distinctive proteins were immunostimulatory. A given tuberculin-positive donor expressed unique patterns of blastogenic reactivity to protein fractions isolated from each of the three recombinant clones. Restriction enzyme digests of the three recombinant BCG inserts revealed distinctive DNA-banding patterns. The immunostimulatory Ag, therefore, are most likely encoded within different regions of the BCG genome, as contained within three distinct inserts. T-cell Western blots further indicated a heterogeneity in the repertoire of BCG-responsive T cells since tuberculin-positive donors varied in the pattern of reactivity to protein fractions isolated from the same recombinant filtrate. Most likely, immunity to M. tuberculosis results from activation of a heterogeneous array of T cells targeted to multiple immunostimulatory Ag. The method we describe should greatly enhance our ability to define the full spectrum of T-cell Ag encoded by mycobacteria, particularly those which are secreted proteins.

Antigens, Bacterial↗

PubMed1993

T cell response to Mycobacterium tuberculosis.

The T cell-mediated acquired immune response to infection with Mycobacterium tuberculosis, both in humans and in experimental models in the mouse, is a complex event believed to involve a variety of T cell subsets that manifest themselves in numerous functions, including protection, delayed-type hypersensitivity, cytolysis, and the establishment of a state of memory immunity. These functions in turn involve the secretion of an array of cytokines, several of which direct cells of the monocyte/macrophage axis to contain and destroy the invading bacilli. This article reviews the development of these ideas, both from clinical experience and from basic research in animal models. In addition, the newly emerging hypothesis that the secreted or export proteins of M. tuberculosis are the key protective antigens leading to the initial expression of acquired specific resistance to this organism is examined.

Animals↗

PubMed1993

Class II major histocompatibility complex molecule expression on murine eosinophils activated in vivo by Brugia malayi.

The Th-2 response to microfilariae of Brugia malayi in BALB/c mice is associated with peritoneal eosinophilia. These eosinophils had an activated hypodense phenotype in vivo and expressed high levels of the class II major histocompatibility complex (MHC). Interleukin 4 up-regulated the class II MHC, whereas gamma interferon inhibited class II MHC expression on eosinophils.

Animals↗

PubMed1993

Induction of murine T-helper-cell responses to the filarial nematode Brugia malayi.

The purpose of this study was to examine the murine T-helper-cell (Th) cytokine response to the human filarial parasite Brugia malayi. In the first 14 days following intraperitoneal inoculation of live microfilariae into BALB/c mice, filarial antigen-driven splenic lymphoid cells produced gamma interferon (IFN-gamma) and little or no interleukin-5 (IL-5). After this time, IL-5 production increased (to 10 to 12 ng per 5 x 10(6) cells) coincident with a marked diminution in IFN-gamma generation. A single subcutaneous immunization with soluble microfilarial antigens also induced an IFN-gamma but no IL-5 response, whereas immunization three times elicited a predominant Th2-like reaction characterized by IL-4 and IL-5 production by CD4+ lymph node lymphocytes and a 10-fold increase in serum immunoglobulin E. The importance of IL-10 in establishing the balance between parasite-specific Th1 and Th2 responses was demonstrated by the ability of neutralizing monoclonal antibody to this cytokine to increase IFN-gamma production by splenic and lymph node cells from mice chronically exposed to live microfilariae or immunized multiple times with soluble filarial antigens.

Animals↗

PubMed1993

Characterization of suppressor function of human alveolar macrophages for T lymphocyte responses to phytohemagglutinin: cellular selectivity, reversibility, and early events in T cell activation.

The predominant immunoregulatory activity of alveolar macrophages (AM) on T lymphocytes is to suppress their responses to antigenic and mitogenic stimuli. The suppressive activity of human AM for T cell responses to phytohemagglutinin (PHA) was further characterized. At ratios of AM to T lymphocytes of 0.4:1 to 1.6:1, AM inhibited the blastogenic response (3H-thymidine uptake into DNA) to PHA by 26 to 87%, respectively. Blood monocytes precultured in vitro for 5 to 7 days inhibited responses to PHA similarly. Freshly isolated blood monocytes, peritoneal macrophages, and A-549 epithelial and CCD-18Lu fibroblast cell lines failed to inhibit T lymphocyte responses. AM were capable of suppressing PHA-induced blastogenesis of purified CD4 cells without the addition of other cells. Cell contact was required for suppression of CD4 cells, as demonstrated using dual chambers. T cells precultured with AM with or without PHA retained the ability to respond to PHA compared with control T cells not precultured with AM. Kinetic experiments showed that AM needed to be added at the initiation of a 3-day culture period for suppression to occur. Analysis of the T cell DNA cycle revealed that AM decreased the percentage of cells entering the synthesis phase of DNA production. Flow cytometry also was used to assess the effect of AM on early markers of T cell activation. AM inhibited the percentage of T cells expressing the interleukin-2 receptor 46 to 83% and the transferrin receptor 58 to 78% at 24 to 48 h after stimulation with PHA. There was no effect of AM on expression of HLA-DR.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1992

Role of the mononuclear phagocyte as an antigen-presenting cell for human gamma delta T cells activated by live Mycobacterium tuberculosis.

gamma delta T cells, both human and murine, have been found to be highly responsive to mycobacterial antigens. However, the role and function of gamma delta T cells in the immune response to Mycobacterium tuberculosis remain largely unknown. In earlier studies, we demonstrated that monocytes infected with live M. tuberculosis were particularly effective inducers of human peripheral blood gamma delta T cells. The present studies were performed to further characterize the interaction between human mononuclear phagocytes, gamma delta T cells, and live M. tuberculosis, in comparison with CD4+ T cells. First, we found that resting gamma delta T cells expanded in vitro by live M. tuberculosis were specific for M. tuberculosis, and that heat killing and washing the mycobacteria removed the antigen(s) for gamma delta T cells. In contrast, the heat-killed mycobacteria retained significant antigenicity for CD4+ T cells. Second, live M. tuberculosis-expanded gamma delta T cells from healthy tuberculin-positive donors did not respond significantly to the antigens in M. tuberculosis culture filtrate, including the 65- and 71-kDa mycobacterial heat shock proteins. Third, the activation of gamma delta T cells by live mycobacteria was dependent on antigen-presenting cells, and mononuclear phagocytes were found to be very efficient antigen-presenting cells both for resting peripheral blood gamma delta T cells and for activated expanded gamma delta T cells. The mononuclear phagocyte carried the necessary costimulatory factors necessary for gamma delta T-cell proliferation. Fourth, the antigen repertoire and HLA requirements for CD4+ memory T cells and those for gamma delta T cells appear to be quite distinct from each other. CD4+ T cells recognized both soluble protein antigens and whole organisms in a class II major histocompatibility complex-restricted manner, whereas gamma delta T cells appeared to recognize only constituents associated with the whole organism and were not restricted by class I or class II major histocompatibility complex molecules. Finally, the assay system described to expand and purify responding CD4+ and gamma delta T cells after stimulation with live M. tuberculosis represented a simple approach to the direct comparison of these two T-cell populations in the interaction with mononuclear phagocytes infected with M. tuberculosis. Such studies provide insight not only into the relative roles of human CD4+ and gamma delta T cells in the human immune response to intracellular bacterial pathogens such as M. tuberculosis but also into the basic biologic role of human gamma delta T cells in antimicrobial immunity.

Antigen-Presenting Cells↗

PubMed1991

Human immune response to Mycobacterium tuberculosis antigens.

Little is known about the immunodominant or protective antigens of Mycobacterium tuberculosis in humans. Cell-mediated immunity is necessary for protection, and healthy tuberculin-positive individuals are relatively resistant to exogenous reinfection. We compared the targets of the cell-mediated immune response in healthy tuberculin-positive individuals to those of tuberculosis patients and tuberculin-negative persons. By using T-cell Western blotting (immunoblotting) of nitrocellulose-bound M. tuberculosis culture filtrate, peaks of T-cell blastogenic activity were identified in the healthy tuberculin reactors at 30, 37, 44, 57, 64, 71 and 88 kDa. Three of these fractions (30, 64, and 71 kDa) coincided with previously characterized proteins: antigen 6/alpha antigen, HSP60, and HSP70, respectively. The blastogenic responses to purified M. tuberculosis antigen 6/alpha antigen and BCG HSP60 were assessed. When cultured with purified antigen 6/alpha antigen, lymphocytes of healthy tuberculin reactors demonstrated greater [3H]thymidine incorporation than either healthy tuberculin-negative controls or tuberculous patients (8,113 +/- 1,939 delta cpm versus 645 +/- 425 delta cpm and 1,019 +/- 710 delta cpm, respectively; P less than 0.01). Healthy reactors also responded to HSP60, although to a lesser degree than antigen 6/alpha antigen (4,276 +/- 1,095 delta cpm; P less than 0.05). Partially purified HSP70 bound to nitrocellulose paper elicited a significant lymphocyte blastogenic response in two of six of the tuberculous patients but in none of the eight healthy tuberculin reactors. Lymphocytes of none of five tuberculin-negative controls responded to recombinant antigens at 14 or 19 kDa or to HSP70. Antibody reactivity generally was inversely correlated with blastogenic response: tuberculous sera had high titer antibody to M. tuberculosis culture filtrate in a range from 35 to 180 kDa. This is the first systematic evaluation of the human response to a panel of native and recombinant antigens in healthy tuberculin reactors and tuberculous patients. Antigens which stimulated prominent lymphocyte blastogenic responses were identified in seven fractions on T-cell Western blot analysis. Two of these may represent previously characterized proteins; the others may contain immunodominant proteins that will require further characterization.

Antibodies, Bacterial↗

PubMed1991

Human Mycobacterium tuberculosis-reactive CD4+ T-cell clones: heterogeneity in antigen recognition, cytokine production, and cytotoxicity for mononuclear phagocytes.

CD4+ T cells regulate the protective immune response which follows exposure to Mycobacterium tuberculosis by activating macrophages through the cytokines the CD4+ T cells secrete. In addition CD4+ T cells have been shown to be directly cytotoxic for antigen-pulsed mononuclear phagocytes (monocytes-macrophages). To explore the functional interaction between mycobacterial antigen-specific CD4+ T cells and mononuclear phagocytes further, CD4+ T-cell clones were derived from healthy purified protein derivative-positive individuals. Five T-cell clones were selected for detailed analysis. None responded to the purified recombinant or native mycobacterial antigens of 14, 19, 65, 71, and 30 (alpha-antigen/Ag6) kDa. However, the T-cell clones demonstrated heterogeneity in antigen recognition as measured by their Western blot (immunoblot) responses. Some T-cell clones made only interleukin 2, while others made only interleukin 4; all produced gamma interferon, although in differing amounts. Four of five T-cells clones were cytotoxic for purified protein derivative-pulsed monocytes at 1:1 and 10:1 effector-target cell ratios. When monocytes infected with live M. tuberculosis were used as targets, comparable levels of cytotoxicity were observed. The cytotoxicity was major histocompatibility complex class II restricted and inhibited by antibodies to ICAM-1 and LFA-1 and not by antibodies to tumor necrosis factor alpha, lymphotoxin, and gamma interferon. Cytotoxicity by CD4+ T cells for monocytes pulsed with mycobacterial antigens or infected with live M. tuberculosis is a common property of these cells and appears to be independent of the repertoire of lymphokines produced and not limited to recognition of defined mycobacterial heat shock proteins. Lysis of heavily infected mononuclear phagocytes may be one manner in which CD4+ T cells regulate host immune response to M. tuberculosis.

Antigens, Bacterial↗

PubMed1991

Selective expansion of human gamma delta T cells by monocytes infected with live Mycobacterium tuberculosis.

Gamma delta (gamma delta) T cell receptor (TCR) expressing T cells comprise 3% of human peripheral blood lymphocytes, yet their role in the immune response remains largely unknown. There is evidence both in humans and in animal models that these cells participate in the immune response to mycobacterial antigens. In mice, exposure to mycobacterial antigens leads to the expansion of gamma delta T cells in draining lymph nodes and lungs. In humans, gamma delta T cell lines with reactivity to mycobacterial antigens have been derived from synovial fluid of a rheumatoid arthritis patient, skin lesions of leprosy patients, and peripheral blood of a healthy tuberculin reactor. Very little is known, however, about the factors which induce human gamma delta T cells to expand. In studies comparing the human T cell response to live and heat-killed Mycobacterium tuberculosis (MT), we have found that monocytes infected with live MT are very effective inducers of human gamma delta T cell expansion. After 7 d of exposure to live MT, gamma delta T cells were greatly increased in all healthy tuberculin reactors (PPD+) tested and frequently were the predominant T cell population. In contrast, heat-killed MT or purified protein products of MT induced a CD4+, alpha beta TCR+ T cell response with very little increase in gamma delta T cells. Furthermore, a similar selective induction of gamma delta T cells was observed when monocytes infected with live Salmonella were used to stimulate T cells. Heat-killed Salmonella, like heat-killed MT, induced a predominantly CD4+ alpha beta TCR+ T cell response. These findings suggest that human gamma delta T cells are a major reactive T cell population during the early stages of infection with living intracellular bacteria and are therefore likely to exert an important role in the initial interaction between host and parasite.

Antigens, Bacterial↗

PubMed1990

Heterogeneity of helper/inducer T lymphocytes. III. Responses of IL-2- and IL-4-producing (Th1 and Th2) clones to antigens presented by different accessory cells.

Murine CD4+ T cell clones have been classified into at least two subsets, Th1 and Th2, on the basis of their distinct lymphokine secretion profiles and functions. In the present study, we compared the functional responses of Th1 and Th2 clones to Ag presentation by splenic B cells and peritoneal macrophages. Th2 clones secreted IL-4 in response to Ag presented by resting B cells, but their optimal proliferation required the addition of IL-1 or a source of IL-1. The degree of IL-1 dependence varied among the four Th2 clones examined. In contrast, Th1 clones secreted IL-2 and proliferated in response to Ag presented by both B cells and macrophages, without any requirement for exogenous IL-1. Furthermore, the proliferation of Th2 clones in response to Ag presented by splenocytes or macrophages was inhibited by an IL-1R antagonist. These results indicate that IL-1 is an important costimulator for the expansion of the Th2 subset of CD4+ T cells. The different requirements for the proliferation of Th1 and Th2 cells may be responsible for the preferential expansion of one or the other subset under different conditions of immunization.

Animals↗

PubMed1990

Heterogeneity of helper/inducer T lymphocytes. IV. Stimulation of resting and activated B cells by Th1 and Th2 clones.

To test the hypothesis that resting and previously activated B lymphocytes differ in their proliferative and differentiative responses to various Th cell-derived stimuli, we have examined the interactions of purified small (resting) and large (activated) murine B cells with rabbit Ig-specific Th1 and Th2 clones in the presence of the Ag analogue, rabbit anti-mouse Ig antibody. Small numbers of Th2 cells induce strong Ag-dependent proliferation of and Ig secretion by both resting and activated B lymphocytes. In contrast, Th1 clones stimulate lower responses of activated B cells and fail to stimulate small resting B cells. An interaction with Th1 clones does make small B cells responsive to the Th2-derived cytokine, IL-4, indicating that Th1 clones are capable of delivering some but not all the stimuli necessary for the induction of humoral immunity. Finally, in order to compare the responses of small and large B cells to cognate interactions and secreted cytokines, we used an autoreactive I-Ak-specific Th2 line. This line induces proliferation of and Ig secretion by I-Ak expressing but not H-2d resting and activated B cells as a result of cognate interactions. However, when the H-2d B cells are bystanders in the presence of cytokine secretion by this Th2 line, or are directly exposed to Th2-derived cytokines, both small and large B cells are induced to proliferate but only the large B cells secrete antibody. These results indicate that the magnitude and nature of antibody responses depend on three principal factors: the cytokines produced by Th cells, the state of activation of the responding B lymphocytes, and whether the B cells are recipients of cognate help or are bystanders at the site of T cell stimulation. Our findings also confirm the view that cognate T-B interactions are most efficient for initiating B cell responses and may allow B cells to subsequently respond to a variety of T cell-derived cytokines.

Animals↗

PubMed1990

Septic cortical thrombophlebitis.

Thrombosis of cortical veins has been postulated as an important cause of seizures and focal neurologic deficits in patients with bacterial meningitis. Diagnoses from autopsies, angiograms, and medical records at Massachusetts General Hospital, 1960-1984, were reviewed to identify patients with septic cortical thrombophlebitis. Only 10 confirmed cases of septic cortical vein thrombosis without sagittal sinus thrombosis were found. Meningitis was present in nine patients; Streptococcus pneumoniae was isolated from the blood or cerebrospinal fluid of five patients. Common clinical manifestations included fever, seizures, and focal neurologic signs. Half the patients survived, but three had persistent disabilities. Cortical vein thrombosis could be documented in only approximately 1% of 790 cases of bacterial meningitis. In 97 patients with meningitis who died and had autopsies, cortical thrombophlebitis was identified in 5%. In autopsied patients, other pathologic processes including arteritis, ventriculitis, cavernous sinus thrombosis, and cerebral infarctions were usually more prominent than venous thrombosis. Cortical thrombophlebitis does not appear to be the major cause of seizures or focal neurologic signs during bacterial meningitis.

Adolescent↗

PubMed1990

Patterns of cytokine secretion in murine leishmaniasis: correlation with disease progression or resolution.

Susceptibility or resistance to infection with Leishmania major correlates with the ability of mice to produce characteristic panels of lymphokines in response to the parasite. To investigate the role of antigen-presenting cells in this phenomenon, we developed a model system which used congenic (H-2d) susceptible and resistant mice. L. major-specific T cells were isolated from infected BALB/c and B10.D2 mice, and the cells were restimulated in vitro on syngenic or congenic antigen-presenting cells. BALB/c L. major-reactive T cells restimulated with either antigen-presenting cell produced high levels of interleukin-4 and low levels of gamma interferon. In contrast, T cells from B10.D2 mice produced gamma interferon. Radiation-induced chimeras reconstituted with BALB/c bone marrow also produced more interleukin-4 in response to L. major than did chimeras reconstituted with B10.D2 bone marrow. To test whether this pattern of cytokine secretion was unique to infection with L. major, we infected the mice with a second intracellular pathogen, Mycobacterium bovis BCG. Mycobacterium-specific T cells from both BALB/c and B10.D2 mice produced interleukin-2 and no interleukin-4. Finally, when BALB/c mice were vaccinated with avirulent L. major, the induced resistance correlated with reduced production of interleukin-4 but no increase in gamma interferon production. Instead, T cells from the vaccinated mice produced high levels of tumor necrosis factor. This suggests that tumor necrosis factor, in addition to gamma interferon, may be involved in resistance to L. major and that interleukin-4 may inhibit the leishmanicidal activity of tumor necrosis factor and/or gamma interferon.

Animals↗

PubMed1988

Heterogeneity of helper/inducer T lymphocytes. II. Effects of interleukin 4- and interleukin 2-producing T cell clones on resting B lymphocytes.

To compare the helper function of murine T cell clones that secrete IL-2 and IFN-gamma (Th1 cells) or IL-4 and IL-5 (Th2), purified resting B cells were stimulated with F(ab')2 rabbit anti-mouse Ig (RAMG) and rabbit Ig-specific, class II MHC-restricted cloned T cells belonging to the two subsets. Both Th2 clones examined induced strong proliferative responses of B cells in the presence of RAMG, as well as the secretion of IgM and IgG1 antibodies. In contrast, the Th1 clones tested failed to stimulate B cell growth or antibody secretion. Th2-mediated B cell activation was dependent on IL-4 and IL-5, and was also inhibited by IFN-gamma or IFN-gamma produced by Th1 cells present in the same cultures. However, the failure of Th1 cells to help resting B cells could not be reversed with neutralizing anti-IFN-gamma antibody. In addition to this inhibitory effect, IFN-gamma was required for the secretion of IgG2a antibody, particularly when B cells were stimulated with polyclonal activators such as LPS. Finally, both sets of T cell clones secreted lymphokines when stimulated with purified B cells and RAMG. These experiments demonstrate that T cells that differ in lymphokine production also differ in their ability to help B cells as a result of cognate interactions at low concentrations of antigens. Moreover, IL-4, IL-5, and IFN-gamma serve different roles in the T cell-dependent proliferative and differentiative responses of resting B lymphocytes.

Animals↗

PubMed1987

Inhibition of B lymphocyte activation by interferon-gamma.

Helper/inducer T cell clones specific for protein antigens and class II MHC determinants consist of two nonoverlapping subsets. One (called Th1) secretes IL 2 and IFN-gamma and the other (Th2) produces BSF1 upon stimulation with antigen or polyclonal activators. By using hapten-binding normal B cells and the B lymphoma line WEHI-279 as assays for B cell helper (maturation) factors, we have shown that Th2 clone supernatants (SN) induce differentiation to antibody secretion, whereas Th1 SN do not. The failure of Th1 SN to activate B cells is due to inhibitory effects of IFN-gamma, because it can be reversed by a neutralizing monoclonal antibody specific for IFN-gamma. Thus, in the presence of this antibody, even Th1 SN stimulate B cell maturation maximally. Conversely, recombinant IFN-gamma inhibits proliferation and differentiation of B cells induced by active Th2 SN. These results demonstrate that IFN-gamma is a potent inhibitor of B lymphocyte activation and can be distinguished from growth and maturation-inducing helper factors that are produced by both subsets of helper T cells.

Animals↗

PubMed1987

In vivo and in vitro characterization of murine T-cell clones reactive to Mycobacterium tuberculosis.

Seventeen helper T-cell clones were derived by stimulating lymph node cells from sensitized C57BL/6 mice with Mycobacterium tuberculosis H37Ra, M. tuberculosis H37Rv, or purified protein derivative. Most clones cross-reacted with Mycobacterium bovis BCG, H37Ra, H37Rv, and purified protein derivative. However, four clones were able to differentiate H37Rv from H37Ra, or BCG from H37Ra and H37Rv. In addition, four other T-cell clones recognized recombinant antigens of 19 and 65 kilodaltons isolated from a genomic expression library of M. tuberculosis by using monoclonal antibodies. All clones were Ia restricted and had the Thy-1.2+ Lyt-1+ L3T4+ Lyt-2- phenotype. On stimulation with antigen, all of the clones tested secreted interleukin-2 and gamma interferon but not B-cell stimulatory factor 1. All of the clones tested induced an antigen-specific delayed-type hypersensitivity response upon local cell transfer, although the magnitude of this response differed markedly among clones.

Animals↗

PubMed1985

New cause for false-positive results with the cryptococcal antigen test by latex agglutination.

The highly specific and sensitive latex agglutination test for cryptococcal antigen detection in cerebrospinal fluid is routine in many hospitals. Contamination of cerebrospinal fluid by a minute amount of syneresis fluid (surface condensation) from agar gave a strongly positive reaction which was heat stable, was not eliminated by pronase treatment, and was not detected by the normal rabbit globulin controls. These observations were valid for three commercially available test kits and could represent a preventable cause of some unexplained false-positive tests despite the use of adequate controls.

Aged↗