The effect of Plasmodium falciparum exo-antigens on the morphology of uninfected erythrocytes.

It was observed that uninfected red cells resuspended in supernatant from Plasmodium falciparum cultures, then examined between a glass slide and cover-slip, assumed varying morphologies. A series of experiments suggested that P. falciparum releases molecules which cause red cells to become stomatocytic (cupped). These molecules, some of which are heat-stable have an apparent molecular weight greater than 12 kDa, are released at or about schizogony, and do not bind tightly to erythrocytes.