Influence of circulating malarial antigens on cell mediated immunity in acute Plasmodium falciparum malaria.

In a group of Thai patients with P. falciparum acute malaria, circulating malarial antigens (CMA) were detected in 27/33 cerebral malaria (CM) cases and 31/43 noncerebral cases. Delayed cutaneous responses to phytohemagglutinin and candidin were found frequently negative in patients with CMA, especially in the CM group. Mean in vitro lymphocyte proliferative responses to lectins were lower in the group of patients with CMA. An inhibitory activity on proliferative responses to phytohemagglutinin of lymphocytes from healthy individuals was exerted by sera containing CMA. Data suggest that CMA from P. falciparum may suppress in vivo and in vitro cell mediated immune reactions.