MONOCLONAL-ANTIBODIES THAT REACT WITH HUMAN BAND-3 RESIDUES-542-555 RECOGNIZE DIFFERENT CONFORMATIONS OF THIS PROTEIN IN UNINFECTED AND PLASMODIUM-FALCIPARUM-INFECTED ERYTHROCYTES

A monoclonal antibody generated against synthetic peptides patterned o n amino acids 542-555 of human band 3, designated 1F4, specifically im munostained Plasmodium falciparum-infected erythrocytes and inhibited the cytoadherence of P. falciparum-infected erythrocytes to C32 amelan otic melanoma cells. 1F4 did not recognize intact band 3 protein on im munoblots, however it was reactive towards proteolytic fragments of ba nd 3. The binding region of another murine monoclonal antibody previou sly reported to recognize the membrane spanning domain of human band 3 , designated B6, was found to also recognize residues 542-555, however its properties differed from 1F4. Mab B6 recognized both infected and uninfected red cells, and reacted only with intact band 3 on immunobl ots. Mab B6 was without effect on cytoadherence. These results demonst rate that monoclonal antibodies reactive against a common peptide sequ ence may bind to different conformations of the peptide sequence and s uggest that the adherent competency of P. falciparum-infected erythroc ytes may result from a change in the surface topography of human band 3 protein.