Evaluation of Natural Killer Activity in Human Schistosomiasis

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  • Department of Microbiology, Vanderbilt University School of Medicine and the Veterans Administration Medical Center, The Bilharziasis Research Project, Centro de Pesquisas “Rene Rachou,”, Nashville, Tennessee 37203, Arab Republic of Egypt

Natural killer (NK) activity was assayed in peripheral blood mononuclear cells of patients with schistosomiasis, of patients following treatment, and of uninfected control subjects. The patient populations were from villages in the Qalyub Province, Egypt and around Belo Horizonte, Brazil. NK activity was assayed by the cytotoxicity of 51Crlabelled K562 target tumor cells. In neither infected population were significant alterations from normal levels found in the percent cytotoxicity per 106 cells, or in the lytic units that expressed 25% cytotoxicity. Likewise, prior treatment (2 and 6 months previously) did not alter the group NK activity detected. Similarly, in the Egyptian study there was no difference in the percentage of large granular lymphocytes between the infected and uninfected groups. In parallel studies in Egyptian and Brazilian schistosomiasis patients we did not find any evidence that this chronic infection consistently altered circulating NK activity.