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)-β has been recently approved for the treatment of relapsing-remitting multiple sclerosis (RRMS). The immunological mechanism by which IFN-β ameliorates MS is still partially unknown. We measured the number of blood circulating CD4+, CD4-, CD8+, and CD8- T cells secreting IFN-γ and IL-4 in 26 RRMS patients followed for up to 9 months of an alternate day s.c. treatment with 8x16 IU of IFN-β1b. Compared to pre-treatment values, a significant (P<0.05) reduction of CD4+, CD4-, CD8+ and CD8- cells producing IFN-γ and of CD4+ and CD4- cells producing IL-4 was observed in MS patients. The IFN-β-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-β treatment on the percentage of IL-4-producing CD8+ and CD8- cells nor in that of natural killer (NK) cells producing IFN-γ. Our results show that IFN-β treatment in MS patients induces a profound and persistent down-regulation of the number of circulating T cells secreting IFN-γ and IL-4 thus suggesting a broader rather than a specific immunomodulatory effect of IFN-β in MS. Copyright (C) 2000 Elsevier Science B.V.