GAMMA GLOBULIN ANTIGENIC TYPES DEFINED BY HEAVY CHAIN DETERMINANTS.

Two populations of immunologically distinguishable 7S gamma globulins in normal human serum and two corresponding antigenic types of myeloma 7S gamma globulins have been detected with rabbit antiserums to proteins associated with pathological conditions, the differences being related to the H-chains of 7S gamma globulin. No relationship exists with type I and type II antigenic classification, determined by L-chains. Human serums with various hereditary gamma globulin (Gm) specificities contain both types of 7S gamma globulin.