[Effect of PHA-T cell conditioned medium (PHA-TCM) on leukemic cells].

Cord blood T cells, purified by nylon wool column, were incubated with PHA for 18 hours, and the supernatant were harvested as PHA-TCM. The results demonstrated that PHA-TCM could significantly inhibit the growth of U937 cells and reduce their 3H-TdR incorporation and spontaneous colony formation. After 3-6 days of treatment with PHA-TCM in culture, part of U937 cells became macrophage-like, latex-phagocytic, and capable of reducing NBT dye. On the contrary, HL-60 cells did not respond to PHA-TCM inhibition, indicating the selective effect of PHA-TCM.