Soluble intercellular adhesion molecule 1-immunoglobulin G1 immunoadhesin mediates phagocytosis of malaria-infected erythrocytes.

We describe an immunoadhesin molecule containing intercellular adhesion molecule 1 (ICAM-1) molecularly fused to hinge and CH2 and CH3 domains of the human immunoglobulin G1 H chain that binds Plasmodium falciparum-infected erythrocytes. This receptor-based immunoadhesin is an effective and specific inhibitor of P. falciparum-infected erythrocyte adhesion to ICAM-1-bearing surfaces, but does not inhibit leukocyte function antigen 1 (LFA-1) interaction with ICAM-1. Furthermore, the immunoadhesin promotes phagocytosis and destruction of parasitized erythrocytes by human monocytes. Each of these modes of action has potential for the therapy of malaria.