TIME-COURSE OF INTERLEUKIN-2 RECEPTOR EXPRESSION IN INTERFERON BETA-TREATED MULTIPLE-SCLEROSIS PATIENTS

The time-course of CD25 (the 55-kD/alpha subunit of the interleukin-2 (IL-2) receptor) expression on CD4 + T lymphocytes, and serum levels o f soluble IL-2 receptors (sIL-2R) and IL-2 were evaluated in relapsing -remitting multiple sclerosis (RRMS) patients treated with interferon beta-lb (IFN beta 1b). Peripheral blood samples were collected before therapy (TO), and 1 (T1), 2 (T2), 3 (T3), 6 (T4), and 12(T5) months af ter therapy initiation. While at T1 and T2, half the patients showed a n increased number of circulating CD I, + CD25 + lymphocytes and an up -regulation of CD25 expression, at T3 this T-cell subset was significa ntly reduced in all the patients. From T4 to T5, however, the progress ive return to pretreatment values was observed. Serum sIL-2R levels we re not significantly affected by IFN beta 1b at any time point. IL-2 w as detected in only a few patients at TO, and never at TI to T5. The t ransient up-regulation of CD25 + expression that occurred in about 50% of the patients may explain the unchanged relapse rate observed durin g the first 2 to 3 months after starting IFN beta 1b therapy. Our stud y demonstrates that IFN beta 1b down-regulates CD25 expression in vivo . This effect, however, was observed only after 3 months of therapy, a nd was followed by the return to pretreatment values after 6 to 12 mon ths. Taken all together, our findings suggest that IFN beta 1b only tr ansiently affects CD25 expression in vivo, and that this effect cannot account for the reported long-lasting beneficial action of LFN beta 1 b on RRMS. (C) 1998 Elsevier Science B.V.