TRYPANOSOMA-THEILERI - ANTIBODY-DEPENDENT KILLING BY PURIFIED POPULATIONS OF BOVINE LEUKOCYTES

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  • 1 January 1982
    • journal article
    • research article
    • Vol. 48  (2) , 289-299
Abstract
Bovine leukocytes were assayed for their cytotoxic activity against T. theileri, a large hemoflagellate parasite of cattle. Cytotoxicity was assessed by 3H-uridine release from pre-labeled parasites and also by light microscopy. Cytotoxicity proved to be totally dependent upon the presence of specific antibody. Serum and Ig fraction of colostrum from normal adult cattle and serum from normal colostrum fed calves mediated cytotoxicity; serum from SPF [serum protective factor] colostrum deprived calves possessed no cytotoxic activity. Neutrophils, eosinophils, monocytes and macrophages obtained from both the peripheral blood and mammary gland of heifers were cytotoxic to T. theileri epimastigotes. Lymphocytes failed to mediate cytotoxicity either in the presence or absence of specific antibody. Despite the large size of this trypanosome all effector cells phagocytosed T. theileri. Phagocytosis by macrophages and eosinophils preceded specific isotope release; however, neutrophils mediated 50% specific isotope release during the phagocytic period, suggesting extracellular cell-mediated lysis.