Determination of subclasses of myeloma proteins M-IgG by enzymatic hydrolysis.

Several methods of determine M-IgG subclasses after hydrolysis with papain and pepsin were compared, and the results were checked by the passive hemagglutination test with erythrocytes using specific antisera. For practical purposes, the papain method was preferred to the pepsin method for recognition of IgG-3 subclass. A shortened method of digestion with papain which distinguishes between the papain-sensitive subclasses, i.e. IgG-1 and IgG-3, is proposed. Apart from its diagnostic value in distinguishing between myeloma (monoclonal) protein subclasses, this work can serve as a basis for preparing protein antigens and production of specific antisera.