Involvement of membrane glycophorins in human erythrocytes invaded by Plasmodium falciparum.

The extent of participation and changes of glycophorins (GPs) and membrane proteins in the merozite-human erythrocyte interaction during the invasion of Plasmodium falciparum (Pf) were studied by immunoblotting techniques. Polyclonal antisera to alpha GP and to its C-terminal fragment (residues 82-131) as well as M and N specific monoclonal antibodies (MoAbs) were used. We examined the GPs in the parasite-free saponin lysates, saponin pellets and the culture supernatants of the infected erythrocytes in comparison with the mock cultured normal RBC. Excepting the usual GP patterns, a GP with molecular weight of 77.5 K (band 1') existed in the parasitized erythrocytes and their saponin pellets and several GP bands ranging from 28K to 54K were present in saponin pellets when probed with anti-GP and anti-peptide C sera. This reflected the disintegration of erythrocyte membrane alpha GP through the invasion of Pf. The alpha 2 GP in the saponin pellets of the parasitized MM erythrocytes surprisingly cross-reacted with the N MoAb, implying that it may have come from the intermingling of the host alpha GP in MM erythrocytes with the parasite alpha GP reacting to N MoAb. The saponin pellets of parasitized erythrocytes preserved a considerable amount of ankyrin, band 3, protein 4.1 and 4.2, while the GP bands were densely mixed with the parasite proteins and the disintegrated products of membrane proteins. Four erythrocyte-binding antigens (EBA) of 143 K, 135 K, 115 K and 107 K recognized by malaria hyperimmune serum were detected in the culture supernatants of Pf, some of them appeared in the infected erythrocytes, their saponin lysates and pellets.