The ultrastructure of red cells infected by Plasmodium falciparum in man

Abstract

Red cells from a patient who had P. falciparum transfusion malaria were studied by transmission and scanning electron microscopy. Two characteristic alterations of the membrane of infected red cells were:

• 1.

  Spur-shaped distortion similar to that observed in P. falciparum in the night monkey and in P. knowlesi in the rhesus monkey. The inability of the spur-shaped red cells to engage in rouleaux probably indicates decreased deformability of the red cell membrane. Since red cells must deform in order to pass through capillaries, obstruction of cerebral capillaries by infected red cells in cerebral malaria may be caused by this rheologic abnormality.

• 2.

  Multiple focal electron dense knob protrusions similar to those observed on the red cell membrane in P. falciparum in the night monkey and P. coatneyi in the rhesus monkey. It is proposed that the knob protrusions are associated in some manner with adhesion to venous endothelium (deep vascular schizogony).