ANTIIDIOTYPIC B-LYMPHOCYTES IN PATIENTS WITH MONOCLONAL GAMMOPATHIES

The prevalence of peripheral blood B cells secreting antibodies reacti ng with the F(ab')(2) fragment of monoclonal Ige was studied in five p atients with multiple myeloma (MM), nine patients with monoclonal gamm opathy of undetermined significance (MGUS) and six healthy controls. A n enzyme-linked immunospot assay allowed direct visualization of antib ody producing B cells. All patients had B cells producing antibodies t o autologous or allogeneic monoclonal IgG. Autoreactive cells were fou nd more frequently than alloreactive cells in seven out of nine patien ts with MGUS and three out of four patients with MM. The same frequenc y of alloreactive cells in the patient groups was detected in healthy individuals. These findings show the existence of B cells producing an ti-idiotypic antibodies which could be a part of an idiotypic network in monoclonal gammopathies.