Mice of inbred strain BALB/c were immunized orally for 10 consecutive days with fresh spleen cells from allogeneic C57BL/10 (B10) donors. The immunized mice displayed significant allotransplantation immunity in vivo as demonstrated by resistance to the growth of allogeneic tumours induced by high doses of tumour cells. No significant changes in the proportion of the major T cell subsets in PP of immunized mice were found 1 or 7 days after the last immunization dose. However, PP cells from orally immunized mice displayed stronger proliferative response after stimulation with cells used for oral immunization than the cells from control animals. Similarly, after stimulation in vitro with specific alloantigens, PP cells from orally immunized mice produced more IFN-gamma than the cells from control recipients. On the contrary, the production of IL-4 was significantly decreased in the immunized mice. The production of IL-2 by PP cells after oral immunization was not significantly changed and IL-10 was only slightly increased. The results thus show that oral immunization with allogeneic cells induces systemic transplantation immunity which can be demonstrated already in Peyer's patches by increased cell proliferation after immunization with specific alloantigens and by changes in cytokine production.

Institute of Molecular Genetics Academy of Sciences of the Czech Republic Prague Czech Republic

Induction of specific transplantation immunity by oral immunization with allogeneic cells