Studies on the role of Ca++ and Mg++ in complement fixation and immune hemolysis. III. The respective roles of Ca++ and Mg++ in immune hemolysis.

It has been shown that Ca++ as well as Mg++ are essential for immune hemolysis. Mg++ can be replaced with a fair degree of efficiency by Co++ or Ni++. The requirement for Ca++ could not be met by Co++, Mn++, Ni++, Mg++, Cd++, Sr++, Ba++, and Zn++. Evidence is presented showing that immune hemolysis takes place in at least two reaction steps: Step 1, involving C′ fixation requires Ca++; Step 2 is a reaction of an unknown nature, which requires Mg++.