Cell-mediated immunity in horses with sarcoid tumors against sarcoid cells in vitro.

Cell-mediated immunity in horses with sarcoid tumor against sarcoid antigens was studied in vitro by means of mixed lymphocyte tumor cell culture assay and lymphocyte-mediated cytotoxicity of 52Cr-labeled target cells. When Mc-1 sarcoid cells were used as stimulatory cells for peripheral blood lymphocytes in the mixed lymphocyte tumor cell assay, a clear difference in the kinetics of the generated lymphocytic proliferative response could be detected between sarcoid and control horses. With sarcoid horses, their proliferative maximum was reached 3 days earlier than that of the control horses, and at this time their proliferative activity was significantly increased over that of control horses. When normal allogeneic fibroblasts were used as stimulatory cells, no such difference between sarcoid and control horses could be seen. The cellular cytotoxicity of peripheral blood lymphocytes from sarcoid and control horses against Mc-1 cells or normal allogeneic fibroblast targets was very low. However, the mean cytotoxicity against Mc-1 was slightly increased for sarcoid horses as compared with that of control horses. In contrast, the cytotoxicity against allogeneic fibroblasts was slightly lower for sarcoid than for control horses. In contrast, the cytotoxicity against allogeneic fibroblasts was slightly lower for sarcoid than for control horses. Furthermore, it was shown that sarcoid horses, but not control horses, had a slightly but consistently increased cytotoxicity against Mc-1 cells as compared with that against normal allogeneic fibroblasts.