Some characteristics of ovine lymphoid cells infected in vivo by Theileria hirci.

A panel of monoclonal antibodies reacting with different subsets of sheep lymphocytes plus a polyclonal rabbit anti-sheep Ig antiserum were used to characterize three Theileria hirci-infected lymphoid cell lines that had been infected and transformed in vivo. In parallel, peripheral blood mononuclear cells of Swedish Landrace sheep were exposed to the same antibodies. Whereas the values obtained for healthy Swedish Landrace sheep peripheral mononuclear cells fell within the range previously described for the sheep, T. hirci-infected lymphoid cells reacted only with monoclonal antibodies specific to major histocompatibility (MHC) class I and class II antigens and to leukocyte common antigen (LCA). The results are discussed in the light of the present knowledge on characteristics of bovine lymphoid cells infected and transformed in vivo and in vitro by the related parasites T. parva and T. annulata. Assumedly, the characteristics of ovine lymphoid cells infected with T. hirci bear likeness to those of bovine cells infected with T. annulata.