Gamma2, Gamma1A, and Gamma1M Antinuclear Factors in Human Sera*

The term "immunoglobulin" is used to refer to one or more of the three classes of serum protein, gammalA, gammaim, and gamma2, each of which is known to contain antibodies. The 7yAand y1M- immunoglobulins have also been referred to as beta2A and beta2M, their electrophoretic mobilities being intermediate between the principal gamma and beta peaks in serum protein electrophoresis. ylA-globulin, like Y2-globulin, is approximately 7 S in its ultracentrifugal characteristics, but differs significantly from 'y2-globulin by other chemical and immunochemical criteria. ylM-globulin is a macro-gamma globulin that has an ultracentrifuga- tion sedimentation coefficient of approximately 19 S.