Crossreacting idiotypes of kappa-monoclonal immunoglobulins M in sera of patients with Waldenström's macroglobulinemia.

Seventeen anti-idiotypic antisera (anti-Id) were prepared against kappa-monoclonal IgM from patients with Waldenström's macroglobulinemia. Their reactivity against homologous and heterologous IgM was tested using an ELISA. Crossreacting idiotypes were only found in two out of 289 investigated antigen-antibody reactions. One anti-Id IgG crossreacted with determinants on polyclonal IgM. These rare crossreactions were observed in Waldenström's macroglobulinemia patients with and without polyneuropathy. The scarcity of common idiotypes on different monoclonal IgM does, however, not constitute a decisive argument against common or related antibody specificities of such monoclonal IgM.