Background: Many proteins released by cells to the blood and other fluids are glycoproteins. One set of glycoproteins carry the ABO blood group determinants and glycoproteins have been shown to be vital in determining the structure and organization of plasma membranes. There is evidence suggesting their important role in cell-to-cell contact, adhesion, hormone interaction and vital transformation. Differences in proteins and glycoproteins in the different human blood groups may influence the invasion process of Plasmodium falciparum. The objectives of the study were to determine whether there are any changes in proteins and glycoproteins of red blood cells upon infection by P. falciparum and whether these protein and glycoprotein changes differ in the various ABO blood groups.
Methods: A Malaysian strain of P. falciparum was cultured in vitro in red blood cells from A, B, O and AB blood groups. Protein and glycoprotein profiles of uninfected and P. falciparum- infected red blood cells from the different human ABO blood groups were analyzed by SDS-PAGE. For protein bands, the gels were stained with Coomassie blue while glycoproteins were visualized following staining of gels using GelCode ® Glycoprotein Staining Kit.
Results: Cell membranes of P. falciparum infected erythrocytes from different ABO blood groups have different glycoprotein profiles compared to uninfected cells. All the infected samples showed a prominent protein band of molecular weight 99 kDa which was not present in any of the uninfected samples while a 48 kDa band was seen in four out of the seven infected samples. The erythrocyte cell membranes of A and AB blood groups showed different glycoprotein profiles upon infection with P. falciparum when compared to those from blood groups B and O.
Conclusion: The two glycoproteins of molecular weights 99 kDa and 48 kDa should be further studied to determine their roles in the pathogenesis of malaria and as potential targets for drug and vaccine development.