Deficient spontaneous cell-mediated cytotoxicity and lectin-induced cellular cytotoxicity by peripheral blood mononuclear cells from Thai adults naturally infected with malaria.

To assess general cytotoxic effector cell capabilities by peripheral blood mononuclear cells from patients with active malaria infections, we examined antibody-dependent cellular cytotoxicity, spontaneous cell-mediated cytotoxicity, and lectin-induced cellular cytotoxicity by using human and chicken erythrocyte, Chang cell line, and K562 cell line targets. By using human erythrocyte and Change cell line targets, we found that Thai adults naturally infected with malaria had significantly impaired lectin-induced cellular cytotoxicity. In addition, spontaneous cell-mediated cytotoxicity was deficient with K562 but not with Chang cell line targets. Finally, no change in antibody-dependent cellular cytotoxicity was observed when chicken erythrocyte or Chang cell line targets were used. These observations, coupled with our previous observations of a physical loss of peripheral blood T cells, the presence of lymphocytotoxic serum antibodies, and defective T suppressor cell generation in patients with malaria, indicate that major alterations in the cellular immune system occur in patients with active malaria infections.