Binding of CD 35, CD 21 and CD 11B monoclonal antibodies and EAC complexes to lymphocytes. A comparative histochemical study.

Using cryostat sections of human tonsils after various pretreatments, the adherence of sheep erythrocyte--antisheep erythrocyte (EA) complexes coated with either fresh mouse complement (EACm) or fresh human complement (EACh) has been compared with the binding of monoclonal antibodies (MAbs) against C3b (CD 35), C3d (CD 21) and iC3b (CD 11b) receptors (clusters). After periodic acid oxidation the binding of MAbs to CD 35, CD 21 was well preserved, whereas EACm and EACh complex adherence and CD 11b binding were abolished. These findings seem to prove that the binding sites for EACm and EACh complexes, as well as those for CD 35, CD 21 clusters (antigenic structure of the C3b and C3d receptors) are different.