Immunity to coccidiosis: adoptive transfer in NIH mice challenged with Eimeria vermiformis

The development of a reliable model for the adoptive transfer of immunity to coccidiosis (infection with Eimeria vermiformis in NIH mice) is described. More than 10(8) of a mixture of spleen and mesenteric lymph node (MLN) cells, given either intravenously or intraperitoneally, were required to transfer a significant degree of protection. Dividing cells, present in the donors at 10 or 14 days after priming, but not at 5 or 19 days, were shown to be the effectors. When examined separately, MLN cells were found to be superior to spleen cells, and the injection of as few as 5 x 10(7) was capable of substantially reducing the oocyst output from a challenge inoculum. The recipients of cells from primed mice had earlier, and sometimes higher, titres of specific antibodies in the serum but, overall, there was no correlation between these titres and protection. Further characterization of the cells responsible for adoptively transferring immunity to this infection should now be possible.     

Immunity to coccidiosis: T-cell control of infection with Eimeria vermiformis in mice does not require co-operation with inflammatory cells

The necessity for co-operation between lymphocytes and myeloid-derived inflammatory cells in the mediation of anti-coccidial immunity was investigated using mice infected with Eimeria vermiformis. Reciprocal exchange of immune lymphocytes between H-2 compatible strains of contrasting susceptibility to infection (resistant BALB/B and susceptible C57BL/10) resulted in successful transfer of immunity in both homologous and heterologous exchanges. Recipients of immune cells, whatever their original response phenotype, expressed a high degree of immunity to infection, indicating that the differential susceptibility of the strains is a property of their lymphoid cells and is not attributable to their capacity to mount inflammatory responses. This conclusion was confirmed by the successful adoptive transfer of immunity into NIH mice previously exposed to 600 rad X-irradiation; at this level of irradiation inflammatory responsiveness is severely depressed. Additional confirmation that strain-response phenotype is lymphocyte dependent and that immune lymphocytes can mediate their effects against E. vermiformis without the intervention of inflammatory cells was obtained from studies on the mucosal mast cell response to infection. No correlation existed between the development of intestinal mastocytosis, an index of T-cell-mediated inflammatory responsiveness, and the expression of resistance to E. vermiformis in BALB/c (resistant), C57BL/10 (susceptible) and NIH (susceptible) mice.     

Oxygen derived free radicals and the course of Eimeria vermiformis infection in inbred strains of mice

Free radical generation by peritoneal leukocytes from BALB/c and C57BL/6 mice was monitored for 18 days following infection with Eimeria vermiformis. Free radical generation occurred earlier and was quantitatively much greater in resistant BALB/c mice than in susceptible C57BL/6 mice, resistance being indicated by a much lower oocyst production and a shorter patent period of E. vermiformis. Plasma greatly enhanced free radical generation in response to a soluble antigen prepared from sporulated oocysts indicating the presence of plasma-borne factor(s) which enhance free radical generation in response to E. vermiformis.     

Susceptibility to coccidiosis: contrasting course of primary infections with Eimeria vermiformis in BALB/c and C57/BL/6 mice is based on immune responses

The effects of three immunosuppressive treatments--whole body irradiation and injections of cortisone acetate or cyclophosphamide, on the course of primary infections with Eimeria vermiformis were investigated in 'resistant' BALB/c and 'susceptible' C57BL/6 mice. Immunosuppression (and the nude athymic mutation in BALB/c mice) resulted in increased reproduction of the parasite in both strains of mice, indicating some immunological control of primary infections. The effect was, however, very much more marked in the BALB/c mice, resulting in an alteration in the relative susceptibilities of the two strains. The findings are discussed and it is suggested that the basis for the differences observed in the course of infection in normal BALB/c and C57BL/6 mice lies in their immune responses to this parasite.     

Vaccination against coccidiosis: host strain-dependent evocation of protective and suppressive subsets of murine lymphocytes

BALB/c mice are normally more resistant than C57BL/6 (B6) mice to infection with Eimeria vermiformis, but these phenotypes can be reversed by oral or parenteral vaccination with a crude antigen prepared from the parasite. Treatment of mice with antibodies specific for CD4+ or CD8+ T cells showed that the increased susceptibility of vaccinated BALB/c mice was associated with the presence of CD4+ T cells. This finding was confirmed when the recipients of CD4+ T cells selected from the mesenteric lymph nodes (MLN) of vaccinated BALB/c mice produced more oocysts after challenge than the recipients of a similar population of cells from sham-vaccinated mice. The residual population of cells (presumably enriched for CD8+ T cells, 'CD8+'), on the other hand, conferred some protection and, in B6 mice, the findings were reversed. Thus, vaccination induced suppressive or protective CD4+ cells and protective or suppressive 'CD8+' cells, depending upon the normal resistance/susceptibility phenotype of the host. Examinations of the isotypes (IgG1, IgG2a) of specific serum antibodies, and of the levels of IFN-gamma and IL-5 cytokines released by MLN cells stimulated ex vivo, did not allow any further characterization of the mechanisms involved.     

Th1/Th2 cytokine profiles and their relationship to clinical features in patients with chronic hepatitis C virus infection

Purpose. An imbalance in helper T-cell type 1 (Th1) and type 2 (Th2) cytokines is suggested to play an important role in the pathogenesis of chronic viral infections, but this issue is not resolved in patients with hepatitis C virus (HCV) infection. The aim of this study was to clarify the relationship between the balance of Th1 and Th2 cytokines and liver damage. Methods. We investigated cytokine levels in the peripheral blood and liver tissue of patients with chronic HCV infection (n = 59) by three different methods; we used flow cytometry to detect intracellular cytokines, and we measured cytokine titers in sera and in the supernatants of lymphocyte cultures with enzyme-linked immunosorbent assays (ELISAs). Results. In both CD4+ and CD8+ cells, interferon (IFN) γ-producing cell populations increased, while there was no difference in interleukin (IL)-10 production, indicating a shift to a Th1 cytokine profile with the progression of liver disease. With respect to the ratio of IFN-γ to IL-10, a correlation was found in CD4+ cells between peripheral blood and liver tissue (r = 0.98; P = 0.0011). Th1 cytokine was predominant in intrahepatic CD4+ cells, while it was predominant in peripheral blood CD8+ cells. Conclusions. These findings indicate a correlation between dominant Th1 response and disease activity and progression. In addition, we suggest that intrahepatic CD4+ T cells play a pathogenetic role in the hepatic injury of HCV infection. Received: August 10, 2000 / Accepted: February 2, 2001     

Immunity to coccidia in chickens: adoptive transfer with peripheral blood lymphocytes and spleen cells

Suspensions of cells prepared from the caecal tonsils and spleen, and the peripheral blood lymphocytes of chickens immune to Eimeria maxima , were tested for their ability to transfer resistance to syngeneic recipients. The intravenous injection of approximately 6 × 10⁸ spleen cells or peripheral blood lymphocytes caused a significant reduction of oocyst production by the challenged recipients, in comparison with controls which were uninjected or given cells from birds susceptible to E. maxima. Peripheral blood lymphocytes appeared to be most effective when obtained 10–15 days after a primary, or 3–10 days after a secondary inoculation of oocysts. The peripheral blood lymphocytes which participate in the early response to challenge of immune birds were not found to be protective. When given intraperitoneally, greater numbers of spleen cells were required to reduce oocyst production, and small numbers of caecal tonsil cells were ineffective. The ability of the various cell suspensions to transfer antibody and cell-mediated responses was monitored with 'marker' antigens. There was some indication that both types of response were involved in protection.     

Genetic control of immunity to parasites. Infection with Trichinella spiralis in inbred and congenic mice showing rapid and slow responses to infection

Summary Strain variation in the response of inbred mice to infection with Trichinella spiralis was reflected in the length of survival of the adult worms, their fecundity and in the number of muscle larvae acquired. Three strains, NIH, SWR and DBA₁ (all H2^q), responded rapidly, expelled most of the adult worms within 12 days and had relatively low burdens of muscle larvae. B10 mice (H2^b) and five related strains (B10.G (H2^q), B10.BR (H2^k), B10.AKM (H2^d), B10.AKM (H2^m) and B10.T(6R) (H2^y2)) responded slowly, retaining adults for more than 12 days and acquiring heavy muscle burdens. The slow response of B10 mice was evident in both old and young mice, in primary and secondary infections and was inherited as a recessive characteristic. No evidence was obtained that slow responsiveness resulted from suppressor cell activity. The results are discussed in relation to the influence of genes located within and without the major histocompatibility complex.     

Secondary Echinococcus multilocularis infection in A/J mice: delayed metacestode development is associated with Th1 cytokine production

The course of Echinococcus multilocularis infection was studied in four different strains of mice after intrahepatic inoculation of a metacestode homogenate. Among these strains of mice, A/J and BALB/c mice were characterized, respectively, as the most resistant and susceptible strains. Although there was no significant difference between the mean surface of hepatic metacestodes of these two strains of mice at any examination time, 13 weeks after infection, the mean metastatic burden of A/J mice was significantly lower than that of BALB/c mice. Moreover, at this time, some BALB/c mice spontaneously died from their infection whereas all A/J mice remained in good health .
The relative resistance of A/J mice to parasite development was associated with a strong and sustained in vitro spleen cell proliferative response to a crude E. multilocularis extract as well as with a high parasite-induced production of IFN-γ and IL-2. The susceptibility of BALB/c mice was on the contrary associated with a high IL-4 production. Interestingly, the parasite extract also stimulated a significant IL-4 production by spleen cells of uninfected susceptible BALB/c mice, but not by control A/J mouse spleen cells. Altogether, these results suggest that the relative resistance of A/J mice to E. multilocularis growth is associated with the development of T cell responses characterized by the production of high levels of Th1 cytokines .     

Immunomodulatory effect of Hypoderma lineatum antigens: in vitro effect on bovine lymphocyte proliferation and cytokine production

This study examines the immunomodulatory effect of a crude larval extract (CLE), obtained from first stage larvae (L1) of H. lineatum , and the purified fractions hypodermin A (HyA), HyB and HyC. Proliferative responses of peripheral blood mononuclear cells (PBMC) from uninfested and previously infested cattle and the production of the cytokines IL-10, IL-4 and IFN-γ, in response to concanavalin A (Con A), were determined. The stimulation index of peripheral blood mononuclear cells from uninfested cattle was significantly lower than that from infested animals with the different antigens assayed. The HyA was the antigen that most inhibited the proliferative response, followed by the HyB, the HyC and the CLE. This hypodermin provoked an increase of IFN-γ and a suppression of IL-10 production that would support a Th1-like cytokine response. The HyB reduced the production of IL-10 stimulated by the Con A in cultures from infested animals. The HyC did not modulate the production of cytokines. Finally, the CLE induced a marked suppression in the production of the different cytokines in cultures from naïve and previously sensitized animals. Our results indicate that Hypoderma larval secretions are comprised of different components (hypodermins) that individually induce distinct but partially overlapping modulatory responses.     

Lymphatic filariasis: parallels between the immunology of infection in humans and mice

Mouse models of Brugia infection have provided much useful quantitative and qualitative information on the immune response elicited by different life cycle stages of filarial worms. Many parallels exist between the immune response in the mouse and the infected human and in this review we highlight areas of topical interest, including the induction of specific cytokine responses and their role in immunomodulation and protective immunity. These studies have reinforced the concept that different life cycle stages of filarial parasites each have their own mechanism of modulating responses so that potentially inflammatory IFN-gamma responses are downregulated. While the precise mechanisms of protective immunity remain to be defined, studies in the mouse have suggested novel pathways, including a possible role for granulocytes.     

Cytokine responses to mitogen and Schistosoma haematobium antigens are different in children with distinct infection histories

Prevalence of Schistosoma haematobium infection in children from two neighbouring villages in Zimbabwe was 77.1% and 40.3%, respectively. The age-intensity data indicated peak intensities of infection at a lower age in the high prevalence village. This study investigated whether the difference in infection histories was reflected in a difference in cytokine profiles between children resident in these two villages. Blood samples were taken to assay for cytokine secretion 1 year after treatment for schistosomiasis. They were cultured with phytohaemagglutinin (PHA), schistosome egg antigens (SEA) or cultured without stimulant and tested for the presence of interleukin (IL)-4, IL-5, IL-10, granulocyte-macrophage colony-stimulating factor (GM-CSF) and IFN-gamma. Blood samples from children from the low prevalence village were more likely to produce IL-4 (P < 0.0001) and produced higher levels of IFN-gamma (P < 0.02) and GM-CSF (P < 0.03) when cultured with PHA for 24 h. Residence in the high prevalence village was associated with production of IL-10 (P < 0.006) and GM-CSF (P < 0.04) in response to culture with SEA and IL-5 (P < 0.02) with PHA for 48 h. The interaction between age and village was not significant for these results; however, there was a significant interaction between age and village for IL-5 detected in blood samples cultured with PHA for 24 h (P < 0.01). These results concur with previous observations that major patterns of cytokine production can be related to immunosuppression, but also indicate an underlying pattern which reflects the importance of history of infection to the immune response.     

Comparative studies on immune responses to infection in susceptible B10.BR mice infected with different strains of the murine nematode parasite Trichuris muris

A comparison of immune responses to infection between groups of B10.BR mice infected with different strains of T. muris , S strain (isolated in Sobreda, Portugal), E strain (isolated in Edinburgh), and E-J strain (originally E strain, which has been maintained in our laboratory, Japan), was performed. In mice infected with E and E-J strains, most of the worms were expelled by day 32 after infection, though the expulsion was faster in E-J strain-infected mice. In contrast, no expulsion was observed in S strain-infected mice by day 32 and egg production occurred on day 32. IL-4 production occurred in concanavalin A (Con-A)-stimulated mesenteric lymph node cells (MLNC) from B10.BR mice infected with E and E-J strains, whereas no IL-4 production was observed in S strain-infected mice. IL-4 production did not occur in normal mice. In comparison with normal mice, high levels of IFN-γ production by Con A-stimulated MLNC were detected in mice infected with every strain of  T. muris . IFN-γ production in S strain-infected mice was greater, occurred earlier and was more persistent than in mice infected with E and E-J strains. IgG1 and IgG2a antibodies to T. muris excretory/secretory antigens were observed in B10.BR mice infected with every strain of T. muris . Antibody production showed similar kinetics. These differences in the expulsion kinetics and IL-4 production in B10.BR mice infected with S, E, and E-J strains suggest the involvement of IL-4 in protection against T. muris infection, and confirm the previous conclusion by Else et al . (1994).     

Immune correlate study on human Schistosoma japonicum in a well-defined population in Leyte,Philippines: II. Cellular immune responses to S. japonicum recombinant and native antigens

Cellular immune responses to specific Schistosoma japonicum recombinant and native antigens were investigated in a defined study population of 155 individuals in the Philippines, where data collected from a 3-year observation of exposure, infection and reinfection pattern were used to categorically classify putative 'resistant' and 'susceptible' individuals. Using peripheral blood mononuclear cells (PBMC) of individuals enrolled in the study, in vitro lymphocyte proliferation and cytokine (IFN-gamma, IL-5 and IL-10) production in response to defined recombinant antigens (97 kDa paramyosin, 22 kDa tegumental antigen, 37 kDa glyceraldehyde-3-phosphate dehydrogenase, 14 kDa fatty acid binding protein and 28 kDa gluthathione-S-tranferase) and native antigen soluble worm antigen preparation (SWAP) were measured. Cellular responses to the recombinant and SWAP antigens suggest that Th1 type of response appear to be important in predicting resistance in this population. Of the five recombinant antigens tested, rPMY induced significant levels of IFN-gamma. The production of IL-10, a Th2-type cytokine was strongly implicated in immune regulation. Of importance was the evidence found for SWAP and rPMY induced IFN-gamma responses in predicting 'resistance'. It was noted that these associations were significant even after the effect of age and sex were accounted for in a multivariate analysis.