HUMAN-COMPLEMENT (C3B) RECEPTORS DEFINED BY A MOUSE MONOCLONAL-ANTIBODY

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  • 1 January 1982
    • journal article
    • research article
    • Vol. 45  (4) , 645-653
Abstract
A monoclonal antibody was prepared against human C3 receptors. The monoclonal antibody termed C3RTo5, inhibited the ligand binding of C3b receptors of human erythrocytes, neutrophils and lymphocytes, but did not block the ligand binding of C3bi and C3d receptors. C3RTo5 reacted only with cells that express C3b receptors. It did not react with cells that do not express C3 receptors or with cells that express C3 receptors other than C3b receptors. The reactivity of C3RTo5 against C3b receptors of human erythrocytes, neutrophils, glomerular cells, tonsil cells or spleen cells could be removed by absorption with human erythrocytes or tonsil cells; absorption with human peripheral T cells or sheep erythrocytes had no effect. In immunoprecipitation studies, a glycoprotein with a MW of 205,000 could be isolated with C3RTo5 from non-ionic detergent lysate of tritiated tonsil cells. A rabbit antiserum prepared against this glycoprotein was able to stain C3b receptor-positive cells, inhibit C3b receptor ligand-binding activity and precipitate a 205,000 MW component. C3RTo5 apparently is a monoclonal antibody with selective reactivity to C3b receptors and presumably to the binding sites within the receptor molecule. Using C3RTo5 further strong evidence was obtained that membrane-bound C3b receptors have a MW of 205,000.