REACTION BETWEEN THE ISOLATION GLOBULAR SUBUNITS OF THE COMPLEMENT COMPONENT CLQ AND IGG-COMPLEXES

The globular sub-units of the Clq complement component were isolated by collagenase digestion of purified Clq followed by gel filtration. They had an apparent mol. wt of 37,000 as determined by gel filtration. The globular sub-units were found to react with IgG immune complexes as shown by their ability to inhibit the reaction of the latter with 125I-Clq; the functional affinity constant for the sub-unit-IgG complex reaction was estimated to be 1.8-5.8 × 104M-1, values similar to that previously found for the reaction between monomeric IgG and intact Clq. Clq thus binds to immune complexes through the peripheral globular sub-units. © 1979.