Comparative studies on surface phenotypes of Theileria lestoquardi and T. annulata schizont-infected cells

Phenotypes of sheep cell lines infected with Theileria lestoquardi or T. an nulata were studied by flow cytometric analysis, following immunolabelling with a panel of monoclonal antibodies reacting to leukocyte differentiation antigens. Cell surface phenotypes of Theileria-infected sheep cell lines d erived ex vivo and in vitro were compared, both with each other and with ce ll lines from cattle undergoing acute T. annulata infection. Besides the no n-lineage specific markers CD45, MH class I and MHC class II, myeloid linea ge-associated antigens and B cell-specific markers were expressed in all fi ve different types of line, suggesting that both T. lestoquardi and T. annu lata had infected the same cell types in sheep as T. annulata in cattle, no tably monocytes/macrophages and B cells. Lineage-specific markers were gene rally expressed at low frequency and intensity; any differences between the five types of cell lines were quantitative, rather than qualitative. Thus, relative rather than absolute differences in cell preference of sporozoite s of T. lestoquardi and T. annulata may contribute to the differences obser ved in previous studies in the course of the infection of sheep with each o f these two parasites and in the infection of cattle with T. annulata.