does not bind to antigen or antibody, but only to the antigen-antibody complex

presents only in human serum

contributes to both acquired and innate immunity in humans

heat labile substances that are inactivated by heating the whey at 56°C for 30 minutes

synthesized in the spleen and lymph nodes

involved in type II (cytotoxic) and type III (immune complex) hypersensitivity reactions

activates cellular immune responses

stimulates the production of protective antibodies

ensures the release of inflammatory mediators (histamine, heparin, etc.) into the tissue

activates fibrinolysis

triggers the apoptosis process

plays an important role in the opsonization of pathogenic bacteria