Humoral antibody and cell-mediated cytotoxicity responses of mice to rat skin xenografts.

Aspects of both the humoral and cell-mediated immune responses of mice to rat skin xenografts were studied sequentially and quantitated. Antirat lymphocytotoxic and hemagglutinating antibodies were first detectable at 7 and 6 days, respectively, after primary grafting and their appearance in serum corresponded to the time of graft rejection. Lymphocytotoxic titers were low after primary grafting but increased greater than 4-fold after secondary grafting. Cytotoxicity of mouse spleen and axillary lymph node cells for 51Cr-labeled rat lymphocyte target cells was first detectable 5 days after primary grafting but was quite low showing a peak of only 7% specific 51Cr release 6 days after grafting. In contrast, the cytotoxicity of mouse spleen and lymph node cells for allogeneic target cells after primary skin allografting was significantly greater. It is suggested that the magnitude of the cell-mediated immune response to skin xenografts is less than the response to allografts and that the quicker and more vigorous rejection of skin xenografts is due to a larger participation of humoral antibody in the rejection process.