Adoptive transfer of CD8alpha+ dendritic cells (DC) isolated from mice infected with Chlamydia muridarum are more potent in inducing protective immunity than CD8alpha- DC.

Chlamydial infections are serious public health concerns worldwide. In this study, we examined the role of dendritic cell (DC) subsets in inducing protective immunity against chlamydial infection using an adoptive transfer approach. We found that CD11c+CD8alpha+ (double-positive, DP) DC, compared with CD11c+CD8alpha- (single-positive, SP) DC isolated from infected mice, are more potent inducers of protective immunity. Specifically, mice pretreated with DPDC from infected mice, upon infection with Chlamydia trachomatis mouse pneumonitis (MoPn), experienced significantly less severe body weight loss and in vivo chlamydial growth. Analysis of MoPn-driven cytokine production by immune cells revealed that mice that were treated with DPDC produced significantly higher levels of Th1 (TNF-alpha, IFN-gamma, and IL-12) but lower levels of Th2 (IL-4, IL-5, and IL-13)-related cytokines than the recipients of SPDC following infection challenge. Moreover, DPDC-treated mice displayed significantly higher levels of MoPn-specific IgG2a production and delayed-type hypersensitivity responses compared with SPDC-treated mice. Furthermore, DPDC isolated from infected mice produced higher amounts of IL-12 and IL-10 in vitro in comparison with SPDC. These data indicate that CD8alpha+ DC have a significantly higher capacity in inducing protective immunity compared with CD8alpha- DC, demonstrating the crucial role of DC1-like cells in eliciting protection against C. trachomatis infection.

CD8+ T-cell tolerance induced by delivery of antigen to the anterior chamber is not the result of de facto intravenous or mucosal administration of antigen.

PURPOSE: We tested whether antigen administration via the anterior chamber (a.c.) was equivalent to intravenous (i.v.) or mucosal administration antigen. METHODS: Ovalbumin (OVA)-specific CD8(+) T cells (OT-I) were enumerated in lymphoid tissues of C57Bl/6 (B6) mice via adoptive transfer after the same amount of antigen was administered via a.c., i.v., or mucosal routes. Lytic activity was measured in B6 and gammadeltaT cell-deficient B6 mice given OVA via a.c., i.v, or mucosal routes after injection with OVA in adjuvant. RESULTS: OVA a.c. induced a pattern of T-cell proliferation distinct from i.v. or mucosal administration. A.c. and i.v., but not mucosal, OVA induced cytolytic T lymphocyte (CTL) tolerance. The inhibition of CTL responses was significantly greater in mice given OVA a.c. rather than i.v. gammadeltaT cells contributed to a.c.-, but not i.v.-, induced CTL tolerance. CONCLUSIONS: A.c. administration of antigen not de-facto i.v. or mucosal administration of antigen.

Analysis of intestinal lymphocytes in mouse colitis mediated by transfer of CD4+, CD45RBhigh T cells to SCID recipients.

Transfer of specific T lymphocyte subsets isolated from the spleens of healthy donor mice into immunodeficient SCID mice leads to chronic intestinal inflammation with characteristics similar to those of human inflammatory bowel disease (IBD). CD4+, CD45RBhigh cells cause disease, whereas CD4+, CD45RBlow and CD8+, CD45RBhigh cells do not. Despite this difference, we demonstrate that all three T cell populations reconstitute the intraepithelial and lamina propria compartments of both small and large intestines of SCID recipients. Therefore, infiltration of lymphocytes alone is not sufficient for disease development. CD4+ lymphocytes that have trafficked to the SCID intestine exhibit a phenotype characteristic of normal mucosal lymphocytes. This includes high expression of alpha E integrin and CD69, expression of CD8 alpha alpha homodimers in some of the intraepithelial lymphocytes, as well as low expression of CD62L and CD45RB. The phenotype of the infiltrating mucosal cells is indistinguishable, with respect to the cell surface markers tested, regardless of whether the starting donor population is CD45RBhigh or CD45RBlow. Severe inflammation is restricted primarily to the colon despite lymphocyte infiltration throughout the length of the intestine. This suggests that some property of the colon microenvironment contributes to inflammation. Consistent with this, transfer of CD4+, CD45RBhigh cells to SCID mice that have significantly reduced numbers of enteric flora results in attenuation of the wasting and colitis. Fewer numbers of donor lymphocytes are recovered from the intraepithelial and lamina propria compartments of reduced flora SCID mice. We hypothesize that the ability of pathogenic cells to traffic to the intestine and mediate colitis may be driven by T cell reactivity to bacteria or bacterial products.

Prospects for anti-rejection therapies based upon CD8-dependent immunoregulation.

In this article we propose that anti-rejection immunotherapies for countering acute allograft rejection can be designed around manipulation of the cell surface phenotype of alloantigen-presenting cells (allo-APCs) in ways that convert them from T cell activators to inhibitors. It is further suggested that a class of molecules, termed "coinhibitors," can be defined that carry out this APC conversion process. Data are summarized indicating that the human lymphoid cell surface molecule CD8 has such a trans-coinhibitor function which is in addition to the cis-coreceptor and adhesin functions traditionally ascribed to it. Antisense and sense gene transfer studies indicate that CD8 on the surface of allo-APCs leads to inhibition of allospecific T cell responders. We have explored the possibility of using protein, rather than gene, transfer as a therapeutic strategy for delivering CD8 to APC surfaces. Two membrane-binding variants of CD8 have been assembled to show retention of the coinhibitor function of native CD8. Immunotherapeutic possibilities associated with these chimeric CD8 polypeptides in the clinical context of renal and other organ transplantation are considered.

Reduced incidence of insulitis in NOD mice following anti-CD3 injection: requirement for neonatal injection.

The incidence of diabetes in NOD mice is reduced following a single neonatal injection of the anti-CD3 antibody, 145.2C11. We now show that the reduction in incidence is greater when the antibody is given in the first than in the third week of life. Anti-CD3 antibody injected in macro-aggregated form did not protect the recipients from insulitis and protection was diminished when elimination of the antibody was accelerated by injecting anti-hamster IgG. Protection was not reversed when anti-CD3 injection was followed by anti-CD4 and anti-CD8. Animals neonatally injected with anti-CD3 were not protected from the induction of diabetes following transfer of spleen cells from diabetic donors. These results contrast with the view that anti-CD3-mediated protection from diabetes depends on a long-lived change in recipient T cells. The findings are consistent with immunosuppression alone being an adequate explanation for the effect of anti-CD3 antibody on susceptibility to diabetes in NOD mice.