ENHANCED DEGRADATION OF SOLUBLE IMMUNOGLOBULIN AGGREGATES BY MACROPHAGES IN THE PRESENCE OF COMPLEMENT

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  • 1 January 1979
    • journal article
    • research article
    • Vol. 37  (3) , 673-680
Abstract
The role of complement [C] in the processing of soluble immune complexes by guinea pig peritoneal macrophages was studied in a homologous system in vitro, using isolated stable Ig[immunoglobulin]G2 aggregates as a model for immune complexes. Under serum-free conditions, peritoneal macrophages were already able to degrade substantial amounts of the available Ig aggregates. Addition of fresh serum to the incubation mixtures caused a marked increase in the rate of degradation. The stimulating effect of fresh serum was C-mediated, because it was abolished by heat treatment or CoVF [cobra venom factor] treatment of the serum and was not seen when C4 or C3-deficient sera were tested. Reconstitution of C4 and C3-deficient sera with purified C4 or C3 restored the stimulating effect of serum on the degradation of the aggregates. Activation of the C system by immune aggregates apparently enhances binding of the aggregates to the cells, which results in the increased degradation observed.