SPLENIC FC RECEPTOR FUNCTION IN HOST DEFENSE AND ANEMIA IN ACUTE PLASMODIUM-FALCIPARUM MALARIA

1b determine splenic Fe receptor function in patients with acute Plasmodium falciparum malaria, the clearance of IgG-coated autologous 51Cr-labeled erythrocytes in 20 patients and 10 normal controls was studied. Clearance half-times were directly correlated with both the absolute parasite count (r =.635, P<.005) and hematocrit (r =.791, P<.001). Clearance half-times in patients varied from 1.0 to 96.3 h (median, 14.8 h) while those of controls ranged from 8.0 to 80.3 h (median, 23.1 h) (P =.10). Nine of the 20 patients had clearance half-times shorter than the lower 95% confidence limit of controls <12.4 h). The clearance of IgG-coated erythrocytes was accelerated after parasites were eliminated from the circulation (P <.05) and returned toward normal 6–8 weeks after the acute infection. Although circulating immune complexes were detectable, there was no correlation between immune complex levels and clearance half-times (P >.05).The failure to increase Fc receptor-mediated red cell clearance in patients with high parasitemias suggests inadequate splenic phagocytic activity in the face of considerable antigenic challenge. These findings indicate that splenic Fe receptor function may be important both in the control of infection and the development of anemia in P. falciparum malaria. © 1990, University of Chicago. All rights reserved.