XENOANTISERUM TO HUMAN C-3 RECEPTORS - ITS PREPARATION AND EFFECT ON THE C3B AND C3D RECEPTORS OF TONSIL CELLS AND THE C3B RECEPTORS OF ERYTHROCYTES AND NEUTROPHILS

Abstract

Antisera directed against complement C3 [component 3] receptors on human tonsil cells were prepared and tested for capacity to block specifically C3 receptors on various types of human cells. The antisera were capable of blocking membrane-bound and solubilized C3 receptors of human tonsil cells. C3b receptors of human erythrocytes and granulocytes were also blocked by the anti-C3 receptor sera. Sheep erythrocyte rosette formation was not affected. Ig[immunoglobulin]G-EoxA [ox erythrocyte-antibody] rosette formation was only slightly reduced by anti-C3 receptor sera. Immunofluorescent staining with anti-C3 receptor sera revealed faint or negative staining of T [thymus-derived] cells and distinct staining of EAC[erythrocyte-antibody-complement complex]-reactive tonsil cells, lymphocytic leukemia cells and granulocytes. Absorption of the antisera with human serum proteins, brain, thymus, liver, [lymphoma] EU-1 cell line cells or trypsinized tonsil cells did not influence the capacity of anti-C3 receptor sera to inhibit C3 receptors, whereas absorption with splenic tissue or tonsil cells completely removed the blocking activity of anti-C3 receptor sera. Absorption with human erythrocytes or kidney removed only the inhibitory effect of the antisera on C3b receptors of tonsil cells, human erythrocytes and granulocytes, but not on C3d receptors of tonsil cells. Antisera prepared with the described procedure apparently contained significant amounts of antibody against C3 receptors; receptors for C3b and C3d apparently differ in antigenicity, and the C3b receptors of tonsil cells, human erythrocytes, granulocytes and probably glomerular cells have common antigenic sites.