TRIFLUOPERAZINE REDUCES THE EXPRESSION OF CD69 IN PHYTOHEMAGGLUTININ-ACTIVATED LYMPHOCYTES

Trifluoperazine (TFP) is a phenothiazine capable of inhibiting lymphoc yte proliferation as well as natural killer cells (NK) and lymphokine- activated killer cells (LAK) cytotoxic activity. CD69 is a surface mol ecule induced by various mechanisms of cellular activation. In the pre sent work the modulation of CD69 expression by TFP was investigated on PHA-stimulated peripheral blood mononuclear cells and compared to tha t of CD25 (IL-2 receptor) expression. Determination of surface molecul es was performed in an indirect immunofluorescence assay using anti-CD 69 or anti-CD25 monoclonal antibodies, and analyzed by flow cytometry. The time course of the expression of these two molecules differed: CD 69 expression was already declining at 48 h, whereas CD25 was still in creasing at 72 h after stimulation. TFP (10 mu M) reduced CD69 express ion by 71.8% at 24 h, 68.4% at 48 h and 24% at 72 h following activati on. In contrast, the same dose of TFP did not significantly affect CD2 5 expression at 24 h but showed an inhibitory effect at later times. T hese results suggest that different activation pathways are involved i n the expression of CD25 and CD69.