Abstract
The leukemic T‐celis of the six patients with T‐cell chronic lymphocytic leukemia (T‐CLL), four with CD4 and CD45R‐positive (CD4+ CD45R*) T‐CLL and two with CD8 and CD45R‐positive (CD8+ CD45R+) T‐CLL pheno‐type were studied for detailed immunologic phenotypic and functional characteristics. The levels of soluble in‐terleukin‐2 receptors were elevated significantly in the serum of all four patients with CD4+ CD45R+ T‐CLL. Moreover, the CD4+ CD45R+ T‐CLL patients' T‐cells, after in vitro stimulation with phytohemagglutinin and concanavalin A, expressed elevated percentages of interieukin‐2 receptors on cells and secreted high interleukin‐2 activity. The B‐cell growth factor (BCGF) activity from three patients with CD4+ CD45R+ T‐CLL was enhanced, but B‐cell differentiation factor (BCDF) activity of the all T‐CLL patients was decreased. Reduced BCGF and BCDF activity of the leukemic T‐cells was one possible mechanism of hypogammaglobulinemia detected in two patients with T‐CLL. All T‐CLL patients' leukemic T‐cells had diminished immunoregulatory functional activity in allogeneic mixed lymphocyte reactions. These observations suggest that leukemic T‐cells from T‐CLL patients have many immunologic functional defects that may be important in their proliferative potential.