In vitro infection of bovine alloreactive cytotoxic T cell lines with sporozoites of Theileria annulata and T parva

Bovine alloreactive cytotoxic lymphocyte (ctl) lines of known target specificity were infected in vitro with sporozoites of Theileria annulata and T parva and cultured in limiting dilution. The phenotypes of the ctl lines both pre- and post infection were assessed using a panel of monoclonal antibodies specific for defined bovine lymphocyte subpopulations. The effector function of the resultant infected cell lines was determined using a Cr 51 release assay and compared to the uninfected control ctl line. The results indicated that T parva sporozoites consistently infected and transformed the ctl lines very efficiently even at the lowest cell doses. In contrast the T annulata sporozoites were largely unable to infect and transform the alloreactive ctl except at the very highest cell and sporozoite doses. A factor which appeared to influence susceptibility to T annulata infection was an increased level of class II expression on the ctl line. None of the cell lines showed cytotoxic effector function after infection with either T annulata or T parva sporozoites.