The syndrome of T8 hyperlymphocytosis: variation in phenotype and cytotoxic activities of granular cells and evaluation of their role in associated neutropenia.

We performed a longitudinal study of the phenotype and functions of granular lymphoid cells from seven patients with T8 hyperlymphocytosis and neutropenia. Whereas cells retained a T3+ T8+ (six cases) or T3- T8+ (one case) phenotype at different examinations, the expression of natural killer (NK)-related antigens (HNK1- and Leu11-defined antigens) exhibited striking variations, some of which were also observed after in vitro culture. Similarly, natural or antibody-mediated cytotoxic activities fluctuated in vivo and in vitro. Cells from the patient with T3- T8+ proliferation were able to inhibit directly the growth of early CFU-GM, CFU-E, and BFU-E and to a lesser extent of late CFU-GM, as shown by cultures of autologous blood or marrow progenitors after depletion (and subsequent addition) of granular cells. In the other six patients with T3+ T8+ cells, no such effect was found. However, after a 24-hour incubation of the progenitors with the granular cells, CFU-GM growth was clearly inhibited; this was not observed in all experiments, a finding which may be related to the spontaneous variations of cell killer functions. Finally, no correlation was noted between the clinical course or extent of lymphoid proliferation and cell function or phenotype or with the monoclonal (two cases), polyclonal (three cases) or germ-line (one case) patterns of T cell receptor beta gene configuration.