Direct cytotoxicity mediated by allogeneic and isogeneic pig lymphocytes modified with fluorescein isothiocyanate.

Cell mediated cytotoxicity (CMC) is restricted by the major histocompatibility complex (MHC) in some animal models but not in others. In order to determine if there was MHC restriction in a CMC experimental model, mononuclear cells from blood of two lines of pigs, (1/1) and (6/6) which are homogeneous to the MHC products (SLA-ABCD), were used. Cytotoxic (1/1) cells were induced in vitro and in vivo against (1/1) mononuclear cells modified with fluorescein isothiocyanate (FITC) and tested against (1/1)-FITC isogeneic and (6/6)-FITC allogeneic cells, without showing MHC restriction of the cytotoxicity. The cytolysis was not due to antibody and K cells because fluoresceinated ovalbumin did not inhibit the test. It was not due to the "altered self" reaction against its own MHC products that sometimes may be induced by allogeneic responses, because the (1/1) anti (6/6) cytotoxic cells did not kill haptenated cells (1/1)-FITC. According to the results there was no evidence of MHC restriction of the CMC response of haptenated cells from pigs of (1/1) haplotype.