Abstract
We have studied on IgG type monoclonal immunoglobulins with antistreptolysin-0 (ASO) activity to elucidate the cause of the discrepancy between the results by streptolysin-O (SLO) inhibition assay (Rantz-Randall) and by passive agglutination assay, and obtained following results.
(1) ASO titer in the M-component varied extremely with the change of reaction order in Rantz-Randall method. This finding indicates that the M-component dose not affect on the target red blood cells for SLO but react directly with SLO.
(2) ASO activity in the M-component was almost completely dropped by reduction and alkylation of the M-component to H and L chains, but the ASO activity was recovered approximately 50% by recombination of H and L chain.
(3) SLO was adsorbed specifically by the M-component conjugated Sepharose column. This M-component column study showed that the affinity of SLO to the M-component increased tenfold in reduced form compared with acidified form.
(4) The hemolytic activity of SLO was completely lost by incubation at 56°C for 30minutes.
(5) The hemolytic activity of cell bound SLO was inhibited almost same degree with free SLO by the M-component. This result suggests that the M-component is an antibody against the hemolytic active site or the antigenic determinant close to the hemolytic site of SLO.
Based on above findings, it is concluded that the ASO activity in M-component is true antibody activity against SLO and the discrepancy between SLO inhibition assay and passive agglutination assay may be caused by the partial differences of SLO antigenicity used in each assay system.
