Heterogeneity of monoclonal immunoglobulins with antistreptolysin-O activity detected in the cases of essential monoclonal gammopathy and multiple myeloma.

Two different types of monoclonal human immunoglobulins (M-components) with antistreptolysin-O (ASO) activity were investigated. The M-component FM with essential monoclonal gammopathy revealed to have an ASO activity, demonstrated not only by streptolysin-O neutralizing assay according to Ranz-Randall's method, but also by passive agglutination assays and precipitation on agar. The ASO activity was shown to reside in the Feb. These findings suggest that the M-component FM have a true antibody activity. On the other hand, ASO activity of M-component TT with multiple myeloma was detected only by streptolysin-O neutralizing assay, but the passive agglutinating assays and precipitation on agar showed no positive results. It has not been fully confirmed if the M-component TT behaves as a true antibody activity. Heterogeneity of the M-components with ASO activity was discussed.