Initial studies on the properties of a bovine lymphoid cell culture line infected with Theileria parva.

Observations were made on a bovine lymphoblast cell culture line, C2, permanently infected with the protozoan parasite Theileria parva. No specific parasite antigen was detected on the C2 cell surface, either by a fluorescent technique or by antibody-dependent cell-mediated cytotoxicity. There was no detectable surface immunoglobulin or secretion of immunoglobulins into the tissue culture medium. Using immunofluorescence and calf thymus and bone marrow antisera, C2 cells were found to share a membrane antigen with normal calf thymus cells, and also to possess a strong transplantation antigen. Bovine antisera against the latter antigen can initiate killing of C2 cells by normal bovine mononuclear leucocytes in antibody-dependent cell-mediated cytotoxicity. C2 cells can also act as weak stimulators in a mixed leucocyte reaction. The possible role of such transformed parasite-infected lymphoblasts in the strong functional immunity that follows recovery from Theileria parva infection is discussed.