Detection of cross-reacting idiotypes in sera of lymphoma patients by inverse monoclonal radioimmunoassay.

An anti-idiotypic IgG1 kappa murine monoclonal antibody (MoAb) Y7 against purified monoclonal IgM lambda 1, derived from a patient with Waldenström's macroglobulinemia, has been generated. This antibody cross-reacted with the tumor-derived idiotypes of patients with B cell non Hodgkin's lymphoma as measured by competitive inverse solid radioimmunoassay using unpurified serum samples. Our results with the inhibition curves of 10 sera of normal donors and 60 sera of lymphoma patients indicate that 21 lymphoma patients revealed cross-reactivities greater than 7%, the mean value observed in normal donors. Of these, 5 sera cross-reacted strongly, in the range of 43-163%, revealing a frequency of positive cross-reactivity for MoAb Y7 of 1/12 sera of lymphoma patients. The generation of a panel of anti-idiotypic antibodies which cross-react with different tumor-derived Ig in serum may be valuable for monitoring the disease in a high proportion of NHL patients.