InVivoMAb anti-mouse CD5

Beginning about 5 weeks after infection, C57BL/6J mice infected with Schistosoma japonicum developed granulomas around parasite eggs trapped in the liver. These granulomas attained peak size about 9 weeks after infection and then spontaneously regressed. This regression was also induced by the injection of serum immunoglobulin G1 but not lymphoid cells from chronically infected mice, but it was conceivable that lymphoid cells from mice infected for 10 weeks could also induce regression. We investigated the possibility of cellular suppression of egg antigen-induced immune responses by coculturing spleen cells from 5- to 6-week-infected mice with spleen cells from mice infected for 10 weeks or longer. Mitomycin C-resistant Thy 1.2+, Lyt 2.2+ splenic T cells from mice infected for 10 to 25 weeks consistently suppressed the egg antigen-stimulated proliferation of spleen cells from 5- to 6-week-infected mice. Suppression was dependent upon specific antigen and optimal concentrations of egg antigen and T suppressor cells. Once induced, the suppressor cells were nonspecific. Cultured T cells from uninfected mice also occasionally suppressed the acute spleen cell proliferative response, but these cells were mitomycin C sensitive. These in vitro observations suggest that granulomatous inflammation in vivo may also be down regulated by suppressor T cells and that these cells may also be implicated in the nonspecific depression of cellular and humoral responses to antigens observed during the course of this infection.

Female BALB/cJ (resistant), C3H/HeJ (intermediate resistant), and C3H/HeDub (susceptible) inbred mice, 4-5 wk old, were infected with Taenia taeniaeformis. Liver sections were stained by an immunoperoxidase technique (avidin-biotin complex, ABC) for the differentiation antigens Lyt-1, Lyt-2, Mac-1, Mac-2, Mac-3, and B220. Binding of ABC to the cytoplasm of hepatocytes around the developing parasite was observed at 4 days postinfection (PI) in all 3 strains of mice, persisting in BALB/cJ and C3H/HeJ liver sections at 5 and 6 days PI, suggesting the presence of high concentrations of biotin, a fatty acid synthesis mediator. Two cell populations were labeled with B220 monoclonal antibodies: lymphocytes and polymorphonuclear (PMN) cells. At 4 days PI the number of labeled PMN cells peaked in infected C3H/HeJ and BALB/cJ mice; however a low number of PMN cells were labeled in infected C3H/HeDub mice. Few lymphocytes bound the B220 antibody in either BALB/cJ, C3H/HeJ, or C3H/HeDub infected mice. The number of Mac-1+ cells detected in infected C3H/HeJ and BALB/cJ liver sections were similar whereas fewer Mac-1+ cells were present in infected C3H/HeDub mice. Mac-2+ cells appeared in high numbers around the growing parasite at 5 and 6 days PI in the liver of C3H/HeDub mice, but not in the liver of BALB/cJ mice. Mac-3+ cells followed a similar pattern to that of the cell population defined by Mac-2. Few Lyt-1+ and Lyt-2+ cells were detected around the parasite site in the 3 strains of mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Immune responses are shaped by several processes that promote responses to pathogens and hinder responses to self. One mechanism that contributes to this polarization in response is negative selection, in which thymocytes that can respond to self-peptide/MHC complexes are deleted from the T cell repertoire. I found here that several coreceptors known to contribute to mature T cell activation also participate in negative selection. Interestingly, these molecules appeared to act in a cooperative fashion. Blocking the contribution of these molecules in fetal thymus organ culture not only prevented negative selection in the CD4+ lineage, but also induced the appearance of autoreactive thymocytes. This is the first demonstration that blocking coreceptor interactions during thymic development can produce autoreactive T cells. The contribution of negative selection to the mature T cell repertoire and to autoimmunity is discussed in light of these results.