Suppression of in Vitro Production of Anti‐U1‐Ribonucleoprotein Antibody by Monoclonal Anti‐Idiotypic Antibody to Anti‐U1‐Ribonucleoprotein Antibody

We produced monoclonal anti‐idiotypic antibody against immunoaffinity purified anti‐U1‐ribonucleoprotein (RNP) antibody from a patient (K.T.), by the cell fusion procedure. The specificity of monoclonal anti‐idiotypic antibody (IgG1, x) was determined by inhibition studies. With the monoclonal anti‐idiotypic antibody, cross‐reactive idiotypes on anti‐U1‐RNP antibodies from unrelated patients with anti‐U1‐RNP antibody was detected in 57% of the samples. The anti‐idiotypic antibody specifically suppressed the in vitro production of anti‐U1‐RNP antibody by lymphocytes from the patient K T., and unrelated patients with a cross‐reactive idiotype, in whom idiotype‐reactive T cells were demonstrated. The results indicate that anti‐idiotypic antibody may modulate the regulation of in vitro anti‐U1‐RNP antibody production.