IMMUNOLOGY

Detailed explanation-1: -Function. CR1 has an inhibitory effect on complement activation by both the classical and alternative pathways. CR1 binds C3b and C4b, thereby mediating phagocytosis by neutrophils and monocytes.

Detailed explanation-2: -The complement proteins C3b and to a lesser extent, C4b can function as opsonins, that is, they can attach antigens to phagocytes. The complement proteins C5b6789n, functions as a Membrane Attack Complex (MAC) causing lysis of Gram-negative bacteria, human cells displaying foreign epitopes, and viral envelopes.

Detailed explanation-3: -CR1 binds C3b and C4b, thereby mediating phagocytosis by neutrophils and monocytes. RBC CR1 is important in the processing of immune complexes, binding them for transport to the liver and spleen for removal from the circulation.