[The expression of CD25 in phytohemagglutinin- or interleukin-2-stimulated human peripheral blood lymphocytes]

The timely expression of a high affinity receptor for interleukin-2 (IL-2R) in human peripheral blood lymphocytes stimulated by various mitogens was examined by cytophotometric evaluation of the number of CD25 bearing cells (CD25+). In resting lymphocyte culture both phytohemagglutinin (PHA, 10 (microg/ml) and 12,13-phorbol dibutirate (PDBu, 10-8 M) and ionomycin (IM, 5 x 10(-7) M) induce the long-lasting increase (during 48 h) in the number of CD25+ cells. Only in competent (not in resting) lymphocytes, pretreated by submitogenic doses of PHA (1 microg/ml), interleukin-2 (IL-2) is capable to induce the time-dependent CD25 expression. When comparing the time course of CD25+ expression and the blasttransformation it was found that the CD25 markers were revealed on small stimulated lymphocytes and all the large blasts were the CD+ cells with high-affinity alphabetagamma(c) receptor for IL-2. In conclusion, the expression of alpha-subunit of IL-2R takes place during the IL-2-dependent stage of T cell proliferation and may be directly induced by IL-2 via IL-2R.