Anti-IL-10 treatment does not block either the induction or the maintenance of orally induced tolerance to OVA.

Herein, the role of IL-10 in the induction and maintenance of oral tolerance was evaluated. The results show that: (1) mice treated with MoAb anti-IL-10 are permissive to the induction of oral tolerance to OVA; (2) anti-IL-10 treatment did not reverse the in vitro blocking of T cell proliferative response found in orally-tolerized mice; and (3) orally-induced tolerance could not be broken by anti-IL-10 treatment. Taken together, these results suggest that IL-10 is not a fundamental cytokine for the establishment and maintenance of oral tolerance.

The development of humoral immunological memory to a T-cell-dependent antigen requires thymic emigrant cells.

Immunological memory is embodied in the rapid and enhanced immune responsiveness to previously encountered antigens. Classically, memory would depend on the presence of small resting long-lived specific lymphocytes which, through clonal expansion after priming with antigen, would be present at higher frequencies than in naive animals. Here we report that T-cell-reconstituted athymic mice, which lack recent thymic emigrants, mount a primary response to a T-cell-dependent antigen, but do not develop memory or the capacity to produce specific anti-TNP IgG1 antibodies during the secondary immune response. On the other hand, if thymocytes are continuously provided during the secondary response, a typical secondary immune response is achieved with high levels of specific IgG1. These results lead us to propose that the development of humoral immunological memory cannot be explained solely by the long life span of primed T lymphocytes, but is rather a dynamic state dependent on the continuous presence of recent thymic emigrants and qualitative functional differences in responder T cells.