Neonatally induced tolerance of class I and class II alloantigens is difficult to achieve in certain I-E non-expressing hosts that receive semiallogeneic cells at birth from strains of mice that express I-E molecules. Although clonal deletion occurs ubiquitously after infusion of the tolerogen-bearing inoculum, the majority of these mice ultimately regain the capacity to reject donor-specific skin graft challenges in adulthood and this is associated with a reacquisition of I-E recognizing and alloreactive T cells as well as a loss of donor chimeric cells. In this study, we determined whether production levels of the eicosanoids prostaglandin E2 (PGE2) and thromboxane B2 (TxB2), both potent modifiers of lymphocyte function, were altered in lymphoid organs concomitant with a breakdown of tolerance in these mice. The levels of TxB2 and PGE2 produced by lymphoid organs were measured in the early/late postpartum periods and immediately before and after skin grafting in B10.S mice (H-2(s)/I-E-) that had been injected at birth with (B10.S x B10.A)F1 (H-2(k/d), I-E+) lymphohematopoietic cells. Phenotypic (e.g., %Vβ11+ T cells) and functional parameters of host donor-reactive effector cell populations along with chimerism were determined simultaneously. We found that TxB2 and PGE2 production fluctuated in the early postnatal periods in naive mice and that the neonatally injected counterparts showed a significant alteration from this pattern, particularly with PGE2. As adults, injected hosts maintained an altered pattern of eicosanoid metabolism and this was accentuated after the rejection or acceptance of a donor-specific skin allograft. Specific patterns emerged after transplant challenge such that neonatally injected mice deleted of Vβ11+ T cells before grafting differed in their eicosanoid secretory profiles; moreover, injected mice that accepted (i.e., tolerant) the donor- specific allografts had a markedly different TxB2 and PGE2 profile than injected/rejecting hosts. In naive mice, the application of 2 subsequent grafts elicited a release of splenic TxB2 and PGE2 that mimicked the pattern seen in the neonatally injected hosts after 1 graft-these latter results give preliminary indication that the generation of memory T cells and the re-exposure to specific alloantigen coincides with a derangement in eicosanoid metabolism. These results suggest that shifts in local eicosanoid metabolism within lymphoid organs may play a critical role in determining the tolerant status of neonatally injected mice upon re-exposure to alloantigen syngeneic to the tolerance-conferring inoculum.
ASJC Scopus subject areas