Studies on the role of Ca++ and Mg++ in complement fixation and immune hemolysis. I. Uptake of complement nitrogen by specific precipitates and its inhibition by ethylenediamine tetraacetate.

Abstract

Summary 1.By means of quantitative precipitin analyses, it has been shown that EDTA inhibits the capacity of specific precipitates to take up the combining component or components of C′ from fresh guinea pig and human sera. In accord with this finding based on weight determination, the hemolytic activity of C′ is not removed by specific precipitates in the presence of EDTA. 2.Ca ++ and Mg ++ , as well as Co ++ , reverse the inhibition of C′ fixation by EDTA. 3.These results suggest the Ca ++ and/or Mg ++ are essential for C′ fixation.