Results.-After priming with phytohemagglutinin for 3 days, a reduced proliferation in the presence of interleukin 2 and interleukin 4 was found. Limiting dilution technique revealed a diminished number of peripheral blood mononuclear cells from patients with CTCL that were capable of proliferating on interleukin 2 but not on interleukin 4 stimulation. Phytohemagglutinin induced a significantly higher release of interleukin 4 (mean+/-SD, 196+/-149.8 pg/mL [n=19] vs 76.4+/-16.4 pg/mL [n=248]) and a significantly lower secretion of interferon-gamma (24.9+/-30.7 U/mL ln=17] vs 47.5+/-43.5 U/mL [n=18]) in the peripheral blood mononuclear cells of patients with CTCL compared with the peripheral blood mononuclear cells of healthy donors (P less-than-or-equal-to 5.02, U test).

Conclusion.-These functional characteristics can be explained by an imbalanced T helper-1/T helper-2 system and allow speculations concerning clinical features such as elevated immunoglobulin serum levels and reduced cytotoxic activity in patients with CTCL.