Naturally occurring circulating immune complexes: normal human serum contains idiotype-anti-idiotype complexes dissociable by certain IgG antiglobulins
Morgan, A.C.; Rossen, R.D.; Twomey, J.J.
Journal of Immunology 122(5): 1672-1680
1979
ISSN/ISBN: 0022-1767 PMID: 312849 Document Number: 140143
Sera from 19 of 23 healthy subjects contained a 24-26S complex (NTC). When passed over heat-aggregated Ig II contained NTC complexes from many donors. A 2nd IgG antiglobulin (ACF) was found in sera from patients with advanced cancer or rheumatoid arthritis. When added to normal donor sera, ACF caused NTC antiglobulin and 7S cytotoxin to dissociate. ACF combined with Fab' of the allogeneic NTC cytotoxin to create a new complex that facilitated complement-dependent cytolysis of malignant melanoma cells. Sera with ACF activity also contained NTC. The cytotoxin in these sera was not detectable until the endogenous ACF and NTC antiglobulin had been removed by adsorption to HAGG Sepharose. In ACF-containing sera, ACF fixed to NTC antiglobulin but would not react with the cytotoxin. ACF reacted with the cytotoxin but not NTC antiglobulin in allogeneic sera. Some natural antibodies circulate with their antigen-combining sites blocked by endogenous antiglobulins. Other antiglobulins, e.g., ACF, can facilitate detection of those blocked antibodies if they react with the components of the complex in a way that facilitates their dissociation.