CHARACTERIZATION OF 2 VACCINIA CD36 RECOMBINANT-VIRUS-GENERATED MONOCLONAL-ANTIBODIES (10 5, 13/10) - EFFECTS ON MALARIAL CYTOADHERENCE ANDPLATELET FUNCTIONS/

Extensive evidence is now available to show that the human CD36 antige n is a cellular receptor for thrombospondin, collagen, modified low-de nsity lipoproteins, and long-chain fatty acids. Moreover, CD36 functio ns as one of the receptors that mediates the adhesion of Plasmodium-fa lciparum-infected erythrocytes to microvascular endothelium. In an att empt to identify new functional sites of this surface glycoprotein, an ti-CD36 monoclonal antibodies were prepared using a vaccinia CD36 reco mbinant virus as a highly efficient immunization vector. In functional studies, one of these antibodies (clone 10/5) strongly inhibited the adhesion of P. falciparum-infected erythrocytes to purified CD36. This antibody also potentiated ADP-induced platelet activation. In contras t, a second antibody (clone 13/10) did not affect the cytoadherence of infected erythrocytes or platelet functions. Previous structural work performed on these antibodies has shown that clone 10/5 is directed a gainst an epitope within the CD36 domain 155-183, whereas clone 13/10 interacts with another antigenic determinant defined by amino acids 30 -76 [Daviet, L., Buckland, R., Puente Navazo, M. D. & McGregor, J. L. (1995) Biochem. J. 305, 221-224]. Taken together, these current studie s show that: (a) the methodology of immunization using recombinant vac cinia virus is a powerful tool in the generation of monoclonal antibod ies directed against polyimmunogenic membrane glycoproteins such as CD 36; (b) the CD36 domain, recognized by clone 10/5 but not by 13/10, is functionally important regarding the adhesion of P. falciparum-infect ed erythrocyte and CD36-dependent platelet activation.