The clinical and cellular aspects of Waldenström's macroglobulinaemia.

Lymphoplasmocitoid lymphoma is a monoclonal proliferation of the B lymphocyte, whose differentiation is blocked at the stage prior to the plasma cell. The neoplastic cells primarily synthetise IgM, rarely IgG or IgA. The IgM thus produced is only secreted in 30% of cases. This secretory variant is known as Waldenström Macroglobulinaemia (WM). This paper describes 4 cases of WM in which the clinical picture included anaemia, secondary immunodeficiency, haemorrhagic syndrome, IgM monoclonal paraproteinemia and both lymphatic and extralymphatic neoplastic proliferation. The monoclonal antibodies and immunoenzyme techniques confirmed that the cells involved were poorly proliferative (K1 negative), preterminal (Ia positive) members of the B line. The B lymphocyte membrane phenotype and determination of the endocytoplasmic isotype permitted the recognition of precursor (sIgM+) and terminal (cIgM+) cells. Secondary immunodeficiency could have been at least partly attributable to the enhanced T CD8 lymphocyte fraction (cytotoxic suppressor) observed in the two cases in which this typing was performed.