Membrane phenotype and functional behaviour of T lymphocytes in multiple myeloma: correlation with clinical stages of the disease.

The distribution of T lymphocyte subsets was assessed using monoclonal antibodies (MoAbs) in 44 untreated patients with multiple myeloma (MM) subdivided according to the clinical stage of the disease. A significant reduction (P less than 0.001) of T lymphocytes was observed only in stage II and III patients. The proportion and absolute number of OKT4 positive cells (helper/inducer phenotype) were significantly reduced in all stages of the disease; this quantitative abnormality was more pronounced in advanced disease. While the proportion of OKT8 positive cells (suppressor/cytotoxic phenotype) was increased above normal in all stages, the absolute number (of OKT8 positive cells) was high only in stage I patients; on the contrary in stage II-III patients the total OKT8 count was reduced compared with normal controls. A significantly reduced OKT4/OKT8 ratio was found in both groups of patients (P less than 0.005). Functional studies, carried out on the unfractionated T cells of patients with MM, demonstrated a consistent helper defect in the ability to induce the differentiation of normal B lymphocytes into antibody producing cells in a pokeweed mitogen driven system. However, the removal of OKT8 positive cells produces a significant increase in helper capacity, suggesting that the reduced helper function of T lymphocytes in toto is probably due to excessive suppressor activity. The possible immunoregulatory role of MM T cell disease is discussed.