[The analysis of immunoregulation of idiotype synthesis by monoclonal anti-idiotypic antibody].

Idiotype (Id) is the epitope in the variable region of immunoglobulin and each immunoglobulin has its own Id. Jerne, in his "Network theory", explained that interaction between Id and anti-Id antibody might regulate cellular and humoral immune response. Many experimental results suggest that anti-Id antibody plays important role on immunoregulations but the mechanism is not known in detail. In the present study, the monoclonal anti-Id antibody (TN 16, IgG1) against M protein (IgG . k) from a patient (TN) with multiple myeloma was prepared with hybridoma technique and the Id positive mononuclear cells (MNCs) in TN peripheral blood were studied by indirect immunofluorescent method. The effect of anti-Id antibody on Id production by TN MNCs was also examined. TN 16 did not react with Cohn Fr. II IgG (pooled normal human IgG) at various concentrations and specifically reacted with TN IgG by radioimmunoassay. The binding between TN 16 and 125I labelled TN IgG was not inhibited by Cohn Fr. II IgG, F(ab')2 fragment of Cohn Fr. II IgG or other IgG k myeloma sera, but only TN IgG and F(ab')2 fragment of TN IgG i.e. idiotype. TN MNCs were stained with TN 16 followed by FITC conjugated anti-mouse IgG. From 9.7 to 18.2% of Id positive cells were detected. The effect of TN 16 on the production of idiotypic IgG was also studied. TN MNCs were cultured with or without TN 16 for 48 hrs and washed to remove TN 16. These cells were resuspended to a concentration of 1 x 10(6)/ml and cultured for 5 days. The production of total IgG was not affected by treatment with TN 16. On the other hand, the production of idiotypic IgG treated with TN 16 decreased from 87.3% ng/ml to 35.0 ng/ml. These results indicate that the mononuclear cells bearing the same idiotype as that of M protein on their surfaces are increased in peripheral blood in this case and that anti-Id antibody suppresses the production of idiotypic immunoglobulin selectivelly.