Effect of IFNβ and anti-IFNβ antibodies on NK cells in multiple sclerosis patients

We analysed longitudinally the numbers of CD3-CD16+ (natural killer cells, NK) and CD3-CD57+ cells (a subset of NK) in 15 IFN beta 1b- and 12. IFN beta 1a-treated relapsing-remitting multiple sclerosis (RRMS) patients. IFN beta 1b (Betaferon(R))-treated RRMS patients showed a rapid and marked reduction in the number of both NK subsets which started I month after therapy initiation, and reached highest significance after 3 months (P = 0.000); however, figures reverted to pre-treatment values following the appearance of anti-IFN beta antibodies. In IFN beta 1a (Avonex(TM))-treated RRMS patients, the decrease in both CD3-CD16+ and CD3-CD57+ cell number was slower but more persistent; anti-IFN beta antibodies were only rarely detected in these patients, and at lower titers than in IFN beta 1b-treated ones. Our findings suggest that NK cells might be one of the major immunological targets of IFN beta-based treatments. (C) 2000 Elsevier Science B.V. All rights reserved.