Anti-antibody activity of a monoclonal macroglobulin.

A monoclonal macroglobulin from a patient with Waldenström macroglobulinemia has been shown to have antiglobulin activity of a new type, namely, that of a true anti-antibody. The protein reacts with human, primate, and rabbit IgM and IgG, only when the target immunoglobulin is complexed to an antigen. The implications of the general findings of antiglobulin activity of monoclonal proteins is discussed in relation to the possible etiology of the disease.