Analysis of the relationship between T cell subsets and in vitro B cell responses in multiple myeloma

To determine whether or not recently reported imbalances in putative immunoregulatory subsets of T-cells are related to impaired B-cell function in patients with multiple myeloma, we enumerated the level of T-lymphocyte subsets in and the pokeweed mitogen induced B-cell differentiation responses of blood mononuclear cells obtained from 13 patients. T-cell subsets were enumerated with the monoclonal antibodies OKT3 (peripheral T cells), OKT4 (helper/inducer cells) and OKT8 (suppressor/cytotoxic cells) using the Ortho Spectrum III fluorescence analyzer. B-cell differentiation was assessed with a reverse hemolytic plaque assay to enumerate immunoglobulin secreting cells in pokeweed mitogen stimulated cultures. Compared to controls, patients showed reduced percentages of OKT4 cells, increased percentages of OKT8 cells, and reduced OKT4/OKT8 ratios. Pokeweed mitogen induced responses were heterogeneous, but markedly depressed in 5/13 patients (hyporesponders). The percentages of OKT4 and OKT8 lymphocytes and OKT4/OKT8 ratios were similar in PWM responders and hyporesponders. Furthermore, there was no correlation between the ratio and the magnitude of the PWM response in individual patients. The data suggest that imbalances in putative immunoregulatory subsets of T cells, although common in multiple myeloma, are not likely a primary cause of impaired in vitro polyclonal B cell responses seen in this disease.