Studies on transplantation immunity. II. The effect of different routes of sensitisation upon the response to allogeneic 51 Cr-labeled lymphoid cells

Mice immunised with (A × CBA) F₁ spleen cells show immune elimination of radiolabeled (A × CBA) F₁ cells in their lymph modes and spleens and sequestration of cells in their livers. The response is graded according to the dose of cells used for immunising. The intraperitoneal route of inoculation and the intravenous one produce the same dose-response curve but differ in potency: the effect is partly attributable to the lower dose of cells reaching lymphoid organs after intraperitoneal injection and partly to RES activity which may act by removing immunogenic material from cells which pass to the circulation by way of the liver. Antigen which does not reach lymphoid tissue fails to immunise. Reticuloendothelial blockade enhances the potency of an intraperitoneal dose of cells.Zones of depressed response are seen for the lymph nodes, spleen, and liver at high sensitising doses, which can apparently be regarded as high dose transplantation tolerance. The discussion explores some connections between the responses to cellular and noncellular antigens, using the fact that the (A × CBA) F₁ cell used for immunising is both an antigen and a lymphocyte.