Distribution of subclasses in a series of 62 sera with IgA paraprotein.

IgA1-2 subclass distribution was determined in a series of 62 sera with diagnosed IgA paraprotein. Throughout the series the participation of IgA1 : IgA2 subclasses showed a ratio 9 : 1 even after division of the series into myeloma and nonmyeloma paraproteinemias. On dividing the series according to the antigenic type of the light chains, IgA2 paraproteins with kappa light chains predominated over the lambda type (6 : 1).