Biomedical subjects

P A Kongshavn

Publications and source records attributed to P A Kongshavn.

At least 19 recordsLinked to original sources

PubMed1992

Identification of immunodominant Trypanosoma musculi antigens recognized by monoclonal antibody and curative immunoglobulin G2a antibody.

Trypanosoma musculi obtained from normal or irradiated (900 rad) hosts or from in vitro cultures were lysed and analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Similar protein banding patterns with a molecular weight (mol. wt) range from 34 to 68 kDa were observed between the two bloodstream forms. In comparison, lysates of cultured parasites showed a unique banding pattern of antigens within the same mol. wt range. Western blot of bloodstream form lysates, probed with immune plasma (IP), revealed a wide range of parasite proteins. However, when probed with the IgG2a-enriched fraction of IP, a major band of approximately 66 kDa was detected on the blot. Several bands of higher mol. wt were also observed. When anti-T. musculi monoclonal antibodies were used to probe the blot, the 66 kDa protein was again recognized. Using indirect fluorescence, live bloodstream form parasites were analysed by flow cytometry and the p66 protein was determined to be a surface molecule. Finally, lysates of 35S-methionine-labelled trypanosomes were immunoprecipitated with Sepharose linked anti-T. musculi monoclonal antibodies and the eluted ligand analysed by SDS-PAGE and autoradiographed. The 66 kDa band was identified, therefore confirming that this protein was of parasite origin.

Animals↗

PubMed1991

Cells within the vascular system capable of mediating trypanocidal activity in vitro.

Cure of Trypanosoma musculi infection involves an effector mechanism mediated by immunoglobulin G2a antibody, C3, and an unidentified effector cell. In the present study, experiments were designed to identify the cell(s) within the vascular system that may be responsible for cure of trypanosomiasis. The ability of various cell populations to mediate killing of trypanosomes in the presence of C3 and immune plasma (IP) was tested in vitro. Blood-derived platelets or leukocytes or Bio-Gel-elicited macrophages or neutrophils were incubated at various concentrations with T. musculi, C3, and IP diluted up to 1 in 8. Trypanocidal activity was dependent upon the presence and concentration of IP and on the number of cells in the wells. Macrophages, neutrophils, and platelets were shown to kill with different potencies. With a 2:1 cell-to-parasite ratio, both macrophages and neutrophils reduced parasite numbers by 2 log, while platelets at a 40:1 ratio mediated a 1 log decrease. In addition, even in the absence of C3, the phagocytes were capable of killing trypanosomes while platelet trypanocidal activity was abrogated. The time course of trypanocidal activity was monitored for macrophages and neutrophils. The number of parasites decreased by 0.5 log by 4 h and 1 to 2 log by 8 h and by 20 h was reduced to zero. Cultured monolayers of endothelial cells were also tested for trypanocidal activity and shown to kill the parasites in the presence of IP and C3. The level of trypanocidal activity was dependent on the concentration of IP.

Animals↗

PubMed1990

Failure to demonstrate a major role for Kupffer cells and radiosensitive leukocytes in immunoglobulin-mediated elimination of Trypanosoma musculi.

Previous studies have indicated that elimination of parasitemia in Trypanosoma musculi infection is brought about by immunoglobulin G2a antibodies, C3, and an effector cell. Experiments were designed to identify the putative effector cell by using several approaches. Infected C5-deficient or C5-sufficient mice treated with silica particles or given 900 rads of radiation 3 days earlier effectively eliminated trypanosomes following administration of immune plasma (IP). Silica-treated, noninfected mice given T. musculi preincubated with IP also cleared the parasites. Radiolabeling studies revealed that uptake of the cleared trypanosomes by the liver in normal mice was relatively low (24%) and fell only slightly (19%) in silica-treated mice. In contrast, uptake of radiolabeled sheep erythrocytes by the liver was normally much higher (47%) and fell drastically (7%) in silica-treated mice. Mice were then immunocompromised by 900 rads of radiation, silica particles, and anti-platelet serum combined before IP-sensitized trypanosomes were given. Leukocyte and platelet counts were both reduced by 95% and sheep erythrocyte uptake by the liver fell from 77 to 5%; however, greater than 99% of the injected trypanosomes were cleared in these mice and uptake of radiolabeled trypanosomes by the liver was similar to that of normal mice. Lastly, in anesthetized mice in which Kupffer cells were excluded surgically from the circulation, greater than 99% of the IP-sensitized trypanosomes disappeared rapidly from the blood. Only 7% of the radiolabel was found in the liver versus 60% in sham-operated mice. The results are interpreted as showing that hepatic Kupffer cells play a minor role in the immune elimination of T. musculi. Likewise, radiosensitive leukocytes and platelets are unlikely to be sole candidates for the putative effector cell that mediates a cure of murine trypanosomiasis.

Animals↗

PubMed1989

The requirement for gamma interferon in resistance of mice to experimental tularemia.

The role of gamma interferon (IFN-gamma) in the host response to experimental tularemia was evaluated in a murine model. C57BL/6 strain mice were given a series of daily intravenous injections of 10(6) units (U) recombinant murine IFN-gamma prior to infection with Francisella tularensis LVS. Three days later, the number of bacteria in the tissues of IFN-gamma-treated mice was found to be less than that in control mice by a factor of 10-20. The effect of IFN-gamma on anti-tularemic resistance was dependent upon the administered dose, with as little as 10(4) U/mouse/day inducing a significant level of enhanced resistance. IFN-gamma was also effective in enhancing resistance to tularemia in the A/J mouse strain which, in comparison with the C57BL/6 strain, is more susceptible to infection. When C57BL/6 mice were treated with a monoclonal antibody directed against murine IFN-gamma, the number of Francisella recovered from their tissues 6 days following infection was increased by as much as 15 times, in comparison with control mice. The results of these experiments clearly indicate that the resolution of experimental murine tularemia is dependent, at least in part, on the participation of IFN-gamma.

Animals↗

PubMed1989

Characterization of protective T cells in the acquired response to Leishmania donovani in genetically determined cure (H-2b) and noncure (H-2d) mouse strains.

The response to reinfection with Ethiopian Leishmania donovani was evaluated in genetically determined noncure (H-2d) B10.D2 mice that are able to resolve infection due to sublethal irradiation pretreatment after inoculation with a low parasite dose and in C57BL/10 mice that demonstrate the genetically determined cure (H-2b) response to L. donovani. It was found that after resolution of primary infection, C57BL/10 (cure) mice and sublethally irradiated B10.D2 (noncure) mice were resistant to rechallenge with L. donovani. Noncure mice inoculated with a low dose of amastigotes were not, however, solidly immune to reinfection. Adoptive-cell transfer experiments were then done to determine the T-cell subset that was associated with resistance to reinfection, and thus the development of immunity, in sublethally irradiated B10.D2 noncure mice and in C57BL/10 cure mice. T-cell-enriched preparations from spleens of immune donors were treated with subset-specific antibodies and complement prior to adoptive transfer in unprimed recipients. The results of the adoptive transfer experiments provide evidence that the genetically determined cure (H-2b) response in C57BL/10 mice and the cure response in genetically determined noncure (H-2d) B10.D2 mice brought about by sublethal irradiation pretreatment are mediated primarily by an L3T4+ Lyt-2- T cell.

Animals↗

PubMed1988

Effect of tumor necrosis factor on growth of Trypanosoma musculi in vivo and in vitro.

The effect of r-TNF on T. musculi is complex. When trypanosomes are incubated in culture with this monokine, TNF exerts a direct anti-trypanosomal effect (Table 3). Similarly, if mice are treated with TNF during the later stages of infection, after the parasitaemia has stabilized, it hastens the elimination of the trypanosomes (Table 2). When TNF is given to mice from the early stage of infection onwards, it enhances the growth of the parasites (Table 1). (This enhanced early growth probably masks any subsequent anti-trypanosomal effect of TNF exerted later in infection). The ability of TNF to promote parasite multiplication is observed even more clearly in in vitro experiments, when peritoneal exudate cells are added to the T. musculi cultures (Table 4). It is conceivable, therefore, that the enhancing effect of TNF in vivo is mediated via a cell present in thioglycollate-induced peritoneal exudate, which mostly comprises macrophages. In summary, the results of these experiments suggest that r-TNF exerts a direct anti-trypanosomal effect while simultaneously promoting the growth of the parasite through an indirect effect mediated via the host's cells, possibly the macrophages.

Animals↗

PubMed1988

Evolutionary traits in human milk proteins.

Human milk has the lowest concentration of protein of any mammalian species. Since the rate of growth of the offspring is negatively related to the protein content of the milk, the time required to double the birth weight is greater in the infant than in any other mammal in which it has been measured. Similarly, in weaned animals, a low protein diet increases the time required to reach maximal growth, senescence and natural death. Human milk protein has the highest whey protein to casein ratio than the milk of any other mammalian species. Our previous experiments have shown that mice fed a 20% whey protein diet exhibit increased resistance to Streptococcus pneumoniae and a humoral immune response significantly higher than that of mice fed most of the commercially available animal and plant proteins in nutritionally similar and adequate formula diets. Other studies have demonstrated that mean and maximal longevity of hamsters fed a 20% whey protein diet is increased in comparison with those fed commercial laboratory feed or a supplemented casein diet of similar nutritional efficiency. Thus, the low protein content and the prevalence of whey protein, which are characteristic features of human milk, are both associated with slow body growth and increased longevity. For human infants, mother's milk is the first and, for most, the only food ingested for a considerable period of time. We, therefore, propose that a trace of Nature's design for the offspring and the evolution of the species can be found in mother's milk.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Activation of macrophages by Entamoeba histolytica extracts in mice.

The effect of Entamoeba histolytica extracts on the production of inflammatory macrophages and the release of hydrogen peroxide (H2O2) and superoxide (O2-) from these cells was examined in C57BL/6 mice. Two different strains of E. histolytica, either virulent (IP:0682:1) or nonvirulent (DKB), were used in this study. The number of macrophages recovered from the peritoneal cavity of mice treated 5 days previously with 150 micrograms of either strain of amoebic extracts was significantly higher than in the saline-treated groups. Macrophages from mice treated with 150 micrograms of the IP:0682:1 strain of amoebic extracts exhibited a powerful burst of oxidative metabolis when triggered with phorbol myristate acetate (PMA). Extract from the non-virulent strain was much less effective in activating macrophages for the production of oxidative metabolites. Thus, a crude extract preparation from E. histolytica, particularly the virulent strain, induces a strong macrophage inflammatory response in which the cells also produce high levels of H2O2 and O2-.

Animals↗

PubMed1988

Enhancing and suppressive effects of tumour necrosis factor/cachectin on growth of Trypanosoma musculi.

The effect of human recombinant TNF on the growth of T. musculi has been investigated. When added to parasites cultured in vitro, TNF inhibited their growth. In the presence of thioglycollate-elicited peritoneal exudate cells, the opposite effect was seen and TNF enhanced the growth of trypanosomes in vitro. Similarly, administration of TNF in vivo during the course of infection led to a net increase in the parasite population. It is suggested that TNF exerts a direct antitrypanosomal effect while simultaneously promoting the growth of the parasite through an indirect effect mediated via the host's cells, possibly the macrophages.

Animals↗

PubMed1988

H-2 restriction in acquired cell-mediated immunity to infection with Francisella tularensis LVS.

The H-2 restriction imposed on the T-lymphocyte-macrophage interaction leading to the expression of acquired cellular immunity was evaluated in an experimental model of infection with the live vaccine strain of Francisella tularensis. Restriction between T cells and macrophages was examined in vitro in cultures containing macrophages from C57BL/10 (B10) mice, T cells from immune B10 H-2 congenic mice, and F. tularensis antigen. The cellular interaction was assayed by the production in the cultures of factors which stimulate thymocyte DNA synthesis. It was observed that homology at the I-A region of the H-2 complex was required for productive T-cell-macrophage cooperation to occur. Restriction was also investigated in an in vivo passive cell transfer system. Spleen cells from immunized B10 mice were injected into naive B10 H-2 congenic mice, which were then challenged with F. tularensis. Enhanced resistance to the challenge infection in recipient mice was used as a marker of a successful T-cell-macrophage interaction. It was found that when the recipient strain shared H-2 I-A region homology with the donor strain, enhanced antitularemic resistance was expressed, whereas homology at the H-2 K or D region was insufficient. Thus, macrophage--T-cell cooperation in immunity to experimental tularemia was restricted at the level of class II determinants.

Animals↗

PubMed1988

Influence of genetic background on host resistance to experimental murine tularemia.

The host response to experimental murine tularemia was examined in different inbred mouse strains. The kinetics of growth of Francisella tularensis live vaccine strain (LVS) in the livers and spleens of A and C57BL/6 mice were monitored, and it was observed that mice of the A strain were more susceptible to the proliferation of LVS than were C57BL/6 mice. The difference was most marked 5 days following infection, when the number of bacteria isolated from the spleens of A mice was found to exceed that of C57BL/6 mice by 100-fold. In addition, the C57BL/6 strain exhibited a more pronounced splenomegaly 8 days after infection than did the A strain. When the response of other inbred strains was evaluated by determining the splenic count of LVS on day 5 postinfection, several levels of antiularemic resistance were observed. Mice of the AKR, BALB/cBy, C57BL/10, and SJL strains were found to be most resistant, while SM mice were most susceptible to the proliferation of LVS. The DBA/2, CBA, 129, C3H/HeJ, and A strains expressed a resistance phenotype which was intermediate between the two extremes, with A and C3H/HeJ mice being somewhat more susceptible than DBA/2, CBA, or 129 mice. The trait of resistance or susceptibility was analyzed genetically in (C57BL/6 x A)F1 hybrid mice and in F2 generation and recombinant inbred (RI) mouse strains derived from C57BL/6 (resistant) and A (susceptible) strain progenitors. The F1 progeny exhibited a level of resistance to infection which was similar to that of the resistant parent. In both the F2 generation mice and the RI strains, a continuous spectrum of resistance levels was observed. The results of these experiments indicate that the genetic background of the host influences host resistance to experimental murine tularemia and that multiple genetic loci are involved in this response.

Animals↗

PubMed1988

Further characterization of the curative antibodies in Trypanosoma musculi infection.

The ability of immune plasma (IP) taken from different donor strains of mice to cure Trypanosoma musculi infection in various recipient mouse strains, when given during the plateau phase of infection, was examined. C57BL/6, B10.A/SgSn, B10.D2/oSn, B10.D2/nSn, DBA/2, and BALB/c strains could be cured of parasitemia (giving 0.4 to 0.8 ml of IP per mouse), whereas A/J and C3H/HeN strains could not (giving up to 1.2 ml of IP per mouse). Noncure appeared to be associated with the high-plateau parasitemias (approximately 10(8] that developed in the latter strains since IP administered early in infection, when the parasite burden was similar to the plateau parasitemias (approximately 10(6] of strains that could be cured, was at least partially effective in A/J and C3H/HeN mice. The IP of any strain tested (C57BL/6, B10.D2/oSn, B10.D2/nSn, DBA/2, A/J, or C3H/HeN) could bring about elimination of trypanosomes in strains able to be cured. The potency of IP from different strains varied, being greater in the strains that developed higher-plateau parasitemias. Potency of IP appears to correlate positively with the titers of trypanosome-specific antibody of the immunoglobulin G2a isotype (the curative antibody). The role of the late-acting complement components was examined. In C5-deficient mice the course of infection was normal, although the elimination phase was delayed by a few days. Cure of parasitemia by IP administered during the plateau phase was equally effective in the presence or absence of C5 in either the donor or the recipient. When tested in vitro, however, IP only exhibited antitrypanosomal activity when added to infected blood taken from C5-sufficient strains of mice. We conclude that in vitro, under the conditions used in the assay, antibody-mediated destruction of the trypanosomes is brought about by complement-mediated lysis. This process, although it probably occurs to some extent, is unlikely to be the major mechanism of trypanosome elimination in vivo.

Animals↗

PubMed1988

The immunoenhancing property of dietary whey protein concentrate.

The plaque-forming cell response to sheep red blood cells was found to be enhanced in mice fed a formula diet containing 20 g lactalbumin/100 g diet in comparison to mice fed equivalent formula diets of similar nutritional efficiency containing 20 g/100 g diet of either casein, soy, wheat or corn protein, egg albumin, beef or fish protein, Spirulina maxima, or Scenedesmus protein, or Purina mouse chow. This effect was manifest after 2 weeks and persisted for at least 8 weeks of dietary treatment. Mixing lactalbumin with either casein or soy protein in a 20 g protein/100 g diet formula significantly enhanced the immune response in comparison to that of mice fed diets containing 20% soy protein or casein.

Adjuvants, Immunologic↗

PubMed1988

Inhibition of expression of cell-mediated immunity by a cell surface-binding antibody directed against T-cell helper factors.

In this study, the effects of a monoclonal antibody, AF3.44.4, which is directed against antigen-specific, T-cell-derived helper factors, were investigated in two models of T-cell-macrophage co-operation. In vitro, cultures of nylon-wool-enriched peritoneal cells from mice immune to Listeria monocytogenes (T cells), macrophages from normal mice and Listeria antigen produced an activity mitogenic for mouse thymocytes (TMF). When AF3.44.4 was added to such cultures, the production of this activity was inhibited in a dose-dependent fashion. Preincubation of T cells with AF3.44.4, followed by its removal, was not sufficient for the inhibitory effect to be manifested. In an in vivo system, when spleen cells from Listeria-immunized mice were transferred to unprimed mice, the latter were protected against subsequent challenge with Listeria. Treatment of spleen cells with AF3.44.4 prior to transfer did not affect their ability to confer resistance upon recipients. It is postulated that AF3.44.4 acts on a population of T cells that is involved in macrophage-T-cell co-operation in vitro and that this population may be different from that involved in macrophage T-cell co-operation in vivo.

Animals↗

PubMed1988

Dietary whey protein inhibits the development of dimethylhydrazine induced malignancy.

This study investigates the influence of two formula diets containing 20 g/100 g diet of either whey protein concentrate or casein or Purina mouse chow, on the humoral immune responsiveness and dimethylhydrazine induced colon carcinogenesis in A/J mice. After 20 weeks of dimethylhydrazine treatment, the number of plaque forming cells per spleen, following intravenous inoculation with 5 X 10(6) sheep red blood cells, was nearly three times greater in the whey protein-fed group than in the casein-fed mice although both values were substantially below normal. After 24 weeks of dimethylhydrazine treatment the incidence of tumors in the whey protein-fed mice was substantially lower than that in mice fed either the casein or Purina diet. Similarly, the tumor area was less in the whey protein group in comparison to either the casein or Purina groups, with some difference between casein and Purina groups. Body weight curves were similar in all dietary groups. In conclusion, a whey protein diet appears to significantly inhibit the incidence and growth of chemically induced colon tumors in mice.

1,2-Dimethylhydrazine↗

PubMed1987

Experimental murine tularemia caused by Francisella tularensis, live vaccine strain: a model of acquired cellular resistance.

We have established a model of experimentally-induced tularemia in mice, using the live vaccine strain of Francisella tularensis. A sublethal, intravenous inoculation of this organism caused in C57BL/6 strain mice an acute infection which lasted approximately 12 days. The clearance of Francisella from the bloodstream was shown to be complete by 5.5 hours postinfection. At this time, approximately twice as many bacteria were isolated from the spleen as from the liver. Mice which had recovered from a primary infection demonstrated a significant resistance to re-infection with autologous Francisella, a memory which persisted for at least 15 weeks. Resistance to experimental tularemia could be passively transferred from infected mice to naive mice by means of non-adherent spleen cells. Cells capable of adoptive transfer of resistance were present at a maximal concentration 7 days following infection, and persisted in significant numbers within the spleen cell population for at least 20 days after infection. Treatment of mice with serum from recovered animals caused a decrease in resistance when measured in the livers, and an increase in resistance when measured in the spleens. Suppression of T cell-mediated immunity during infection by treatment with cyclosporin A resulted in a dramatic increase in the tissue bacterial counts. Cyclosporin A-induced suppression of antitularemic resistance was first noted 2-3 days following infection and remained apparent for at least 8 days. The results of these experiments demonstrate that resistance to experimental murine tularemia is mediated predominantly by a cell-mediated mechanism. This mechanism involves T cells which become activated as early as 2-3 days following infection. Experimental, non-lethal infection with Francisella tularensis is thus an excellent model for investigating the mechanisms of acquired cellular immunity.

Animals↗

PubMed1987

Immunosuppression and splenomegaly in Entamoeba histolytica infection in mice.

Intestinal amoebiasis caused by Entamoeba histolytica trophozoites in mice is accompanied by a depression in the ability of this host to develop an immune response to sheep red blood cells. The number of splenic plaque-forming cells was reduced in mice inoculated intracecally with 2.5 x 10(5) trophozoites at 15, 25, 40, 65 and 75 days after infection when compared with non-infected mice. It was found that there was no significant difference between the spleen weight of the infected and non-infected control animals at 5 and 10 days following infection. However, a significant increase in spleen weight was observed by 15 days of infection and the spleens remained enlarged until termination of the experiment at 75 days. Thus, there was an inverse correlation between the PFC response and the spleen weight of infected animals.

Amebiasis↗

PubMed1987

Graft-versus-host reactions in the beige mouse. An investigation of the role of host and donor natural killer cells in the pathogenesis of graft-versus-host disease.

To investigate the role of natural killer (NK) cells in the induction and pathogenesis of graft-versus-host (GVH) disease, +/beige (+/bg; normal NK cell activity) and beige/beige (bg/bg; deficient NK cell activity) parental C57BL/6 (B6) lymphoid cells were used to induce GVH reactions in either B6 X C3H/Hej +/bg (+/bgF1) or B6 X C3H/HeJF1 bg/bg (bg/bg F1) hybrid mice. When B6 bg/bg parental lymphoid cells (PLC) were injected into bg/bg F1 mice, early splenomegaly, early severe suppression of the plaque-forming cell (PFC) response to sheep red blood cell (SRBC), and only partial suppression of T cell mitogen responses to concanavalin A (Con A) and phytohemagglutin (PHA) were observed on day 12 after GVH induction. In the same GVH combination, slightly augmented NK cytotoxic activity was induced and no GVH-induced moderate-to-severe pathological alterations in the liver and pancreas were observed. When bg/bg PLC were injected into +/bg F1 mice, early splenomegaly and pronounced immunosuppression of the PFC response to SRBC and partial suppression of Con A and PHA responses were observed on day 12 after GVH induction. In this combination (bg/bg----+/bg F1), significant NK cell activity was induced, but no moderate-to-severe histopathological alterations were observed. In contrast, when B6 +/bg PLC were injected into either +/bg F1 or bg/bg F1 hybrids, early splenomegaly, and severe immunosuppression of both the PFC response to SRBC and the T cell mitogen responses to Con A and PHA were observed by day 12--which persisted until day 30 after GVH induction. Furthermore, high NK cell activity was recorded and moderate-to-severe histopathological alterations appeared in both +/bg F1 and bg/bg F1 recipients. These results show that the bg/bg PLC can induce GVH-associated early splenomegaly and immunosuppression of the PFC response to SRBC in both the bg/bg F1 and +/bg F1 hybrids, but that it failed to induce moderate-to-severe histopathological alterations, even though NK cell activity of host origin was activated during GVH reactions. Conversely, when +/bg donor cells were used to induce the GVH reaction, splenomegaly and immunosuppression, as well as moderate-to-severe histopathological lesions were induced. These results suggest that donor NK cells rather than host NK cells play an active role in GVH-associated tissue damage, which in turn contributes to the long-term suppression.

Animals↗