Cellular and humoral aspects of heterotransplantation immunity.

In the present report, I attempted to identify the nature of humoral and cellular factors in heterotransplantation immunity, assuming that the former would confer on the animals transplantation immunity by passive immunization with serum, while the latter would be adoptively transferred to recipients with sensitized cells. A group of mice was inoculated with rat ascites hepatoma cells. Eighteen to 23 days after the transplantation, the serum and nucleated cells were collected from the peritoneal fluid, spleen and mesenteric lymph node were pooled separate ly. Then, the extraction of effective substances was performed by treatment of the specimens with sonic oscillation, salting out with ammonium sulfate, Sephadex column chromatography, sucrose density gradient centrifugation, etc. 1. The active factor in immune sera was found to be 7S IgG, whereas no high molecular immunoglobulin effective in accelerating the rejection of target cells could be found. 2. Passive transfer of transplantation immunity was accomplished with a soluble extract from sensitized cells. The active agent was specific for the sensitizing cells and behaved like a 19S IgM in demonstrating a sensitivity to 2-mercaptoethanol. 3. Judging from the results of experiments employing a temporary deprivation of complement as well as blockade of peritoneal phagocytes, co operation of complement and phagocytic cells seemed to be necessary for the full activity of the immune serum against the graft. 4. On the contrary, the sensitized cell sonicate exerted its effectiveness in co-operation with complement and non-phagocytic cells, probably lymphoid cells, of recipient mice.