Immunofluorescent and immunoelectron microscopic localization of protein antigens in red cells infected with the human malaria Plasmodium falciparum.

Erythrocytes infected with the human malaria Plasmodium falciparum produce elevations of the surface membrane of the red cell called knobs. Through the use of transmission electron microscopy and a post-embedding protein A-immunogold technique, it was possible to show changes in the distribution of band 3, glycophorin A and spectrin in the region of the knob. These proteins appeared to be aggregated or condensed in the area of the knob, whereas the remainder of the red cell surface showed no such dense clusters; haemoglobin and the histidine-rich protein of P. lophurae could not be localized to the knobby protuberances. It was not possible to detect any changes in protein distribution using the light microscope and indirect immunofluorescence.