Polyclonal immunoglobulin deficiency in myelomatosis and macroglobulinaemia.

Polyclonal Ig of one or other class was significantly reduced in 82% of subjects with monoclonal protein disease (MPD). Ig deficiency was equally frequent with all classes of monoclonal Ig, but was considerably more common in myelomatosis than in benign MPD. Polyclonal IgG isolated from sera containing monoclonal IgG, IgA or IgM was normal in regard to electrophoretic heterogeneity and proportions of κ- and λ-chains. Peripheral lymphoid tissues from most patients with Ig deficiency failed to synthesize the corresponding polyclonal Ig in vitro. Monoclonal protein was synthesized by macroglobulinaemic lymph node tissue, but monoclonal proteins were not synthesized by nodes from subjects with myelomatosis. Polyclonal Ig deficiency in macroglobulinaemia can be ascribed to peripheral spread of neoplastic cells, but the same process does not apparently account for Ig deficiency in typical cases of myelomatosis.