Interferon-β treatment in multiple sclerosis patients decreases the number of circulating T cells producing interferon-γ and interleukin-4

Systemic administration of interferon (IFN)-beta has been recently approved for the treatment of relapsing-remitting multiple sclerosis (RRMS). The immunological mechanism by which IFN-beta ameliorates MS is still partially unknown. We measured the number of blood circulating CD4(-), CD4(-), CD8(+), and CD8(-) T cells secreting IFN-gamma acid IL-4 in 26 RRMS patients followed or up to 9 months of an alternate day s.c. treatment with 8x6 IU of IFN-beta 1b. Compared to pre-treatment values, a significant (P<0.05) reduction of CD4(+). CD4(-), CD8(+) and CD8(-) cells producing IFN-<gamma> and of CD4(+) and CD4(-) cells producing IL-4 was observed in MS patients. The IFN-beta -associated effect was evident soon after the beginning of the treatment and persisted for the entire follow-up period. We did not observe any effect of IFN-beta treatment on the percentage of IL-4-producing CD8(+) and CD8(-) cells nor in that of natural killer (NK) cells producing IFN-gamma. Our results show that IFN-beta treatment in MS patients induces a profound and persistent down-regulation of the number of circulating T cells secreting IFN-gamma and IL-4 thus suggesting a broader rather than a specific immunomodulatory effect of IFN-beta in MS. (C) 2000 Elsevier Science B.V. All rights reserved.