Anti‐idiotypic antibodies specific for a pathologic anti‐Pr₂ cold agglutinin

The heterogeneity of human red cell (RBC) autoantibodies may be assessed by using anti-idiotypic antibodies. In this study, mouse monoclonal anti-idiotypic antibodies were produced against a pathologic RBC autoantibody with anti-Pr2 specificity. Epstein-Barr virus-transformed B-cell clones were established from a patient who had splenic lymphoma and associated immune hemolysis due to an anti-Pr2 cold autoantibody. Two of the eight clones producing this autoantibody were used to immunize mice for the establishment of hybridomas, and four monoclonal anti-idiotypic antibodies were isolated (2 IgG1 kappa and 2 IgM kappa). By the use of these anti-idiotypic antibodies, strong crossreactivity was seen on enzyme-linked immunosorbent assay with other anti-Pr2-producing clones from the same patient, but no cross-reactivity was seen with RBC autoantibodies from other individuals having anti-Pr or different specificities. Each of the anti-idiotypic antibodies inhibited hemagglutination (HA) by the patient's anti-Pr2 but failed to inhibit HA by antisera of a different RBC specificity. Cross-competition experiments indicated that all of the anti-idiotypic antibodies may recognize the same or a closely related idiotope on the anti-Pr2 autoantibody. These studies suggested that the four anti-idiotypic antibodies are directed against the same (or closely related) idiotypic determinant(s), unique to this patient's anti-Pr2 and located at or near the antigen-binding site. These anti-idiotypic antibodies may be useful tools for the study of this autoimmune response or for the development of immune therapeutic agents.(ABSTRACT TRUNCATED AT 250 WORDS)