Abstract
The main chromatographically separated macroglobulins gave 2 well-defined precipitation lines against anti-macroglobulin sera produced in the rabbit. Chromatographically separated gamma-globulin fractions did not give detectable precipitation lines against the same antisera. Against anti- (whole gamma-globulin) sera (Agamma), macroglobulin fractions gave rise to the same lines as against anti-macroglobulin seraand an extra weaker line related to that produced when gamma-globulin fractions reacted with Agamma sera. Apparently globulin fractions reacted with Agamma sera. Apparently a gamma-globulin-type impurity occurred in the main macro-globulin fractions at a concentration such that is did not, on injection, stimulate the formation of its respective antibody. Subsidiary macro-globulin fractions contained such an impurity in higher concentration. The absence in the antimacroglobulin serum of the antibody corresponding to the extra precipitation line was shown by absence of the line when the whole gamma-globulins diffused against anti-macroglobulin sera.