Impaired interleukin-2 production by T-lymphocytes in polycythemia vera

T-lymphocyte function was investigated in a group of eight patients with polycythemia vera (PV) and 13 normals. Responsiveness of T-cells to stimulation by mitogen was significantly impaired in the PV patients (p = .02). Analysis of immune cell subpopulation composition by assessment of cell surface phenotype did not reveal imbalances that could account for impaired T-cell proliferative ability in PV patients. Addition of recombinant human interleukin-1 to PV mononuclear cell cultures did not enhance proliferative ability. Addition of recombinant human interleukin-2 to cultures had no effect on maximum mitogen stimulation in normals but significantly improved responses in PV patients (p less than .02), correcting them to normal levels. Measurement of interleukin-2 production by stimulated cultured mononuclear cells confirmed subnormal IL-2 production by PV T-cells (p less than .00005). Impaired IL-2 production could conceivably contribute to the pathogenesis of PV by limiting the ability of IL-2-dependent cells to regulate hematopoiesis.