Distribution of a set of idiotopes detected by a monoclonal antibody panel in 42 cases of chronic lymphocytic leukaemia: definition of potential targets for immunotherapy

Using a panel of 14 monoclonal V region reactive antibodies generated against a single IgG1 lambda paraprotein we have identified shared idiotopes in a group of 42 patients with chronic lymphocytic leukaemia (CLL). The specificity of cellular staining by indirect immunoperoxidase was confirmed in the majority of cases by an ELISA assay using secreted idiotypic immunoglobulin. In a few cases weak cellular binding by the panel antibodies could not be confirmed as specific for immunoglobulin. Four monoclonal antibodies specific for lambda chain determinants reacted with 5-29% of lambda expressing CLLs but the significance of this is uncertain as the antibodies may be recognizing one of the commoner V lambda subgroups. Two antibodies, which are only weakly reactive with normal serum immunoglobulin, detected heavy chain associated idiotopes which were expressed by 7% and 14% of CLL cases. One of these antibodies detects an idiotope which was expressed significantly more frequently by CLL associated immunoglobulin than by a panel of paraproteins. Such preferentially expressed idiotopes may be useful in investigating the biology of this disorder as well as providing attractive targets for immunotherapy.