Natural killer (NK) cells can affect the outcome of adaptive immune responses. NK cells, but not NK1.1+T cells, were found to participate in the development of myasthenia gravis (a T cell-dependent, B cell- and antibody-mediated autoimmune disease) in C57BL/6 mice. The requirement for NK cells was reflected by the lack of a type I helper T cell response and antibodies to the acetylcholine receptor in both NK1.1+ cell-depleted and NK cell-deficient IL-18-/- mice. These findings establish a previously unrecognized link between NK cells and autoreactive T and B cells.

Interferon-beta (IFN-beta) is currently the most commonly used treatment of relapsing-remitting multiple sclerosis (MS). At the time of this study, two preparations of IFN-beta were available, IFN-beta-1a (Avonextrade mark) and IFN-beta-1b (Betaferon(R)), which both can elicit an immune response with the development of anti-IFN-beta antibodies. Direct comparisons between these two preparations regarding antibody frequencies have, however, been difficult to perform, because two different analysis methods measuring partly different biological effects of IFN-beta have been employed. In the present study, binding and neutralizing anti-IFN-beta-1a and -1b antibodies were detected in parallel by an independent, well-acknowledged, interferon research laboratory using an immunoassay and a cytopathic virus inhibition assay. Five per cent of patients treated with IFN-beta-1a intramuscularly (n = 20) had neutralizing antibodies (NABs) compared with 44% of patients treated with IFN-beta-1b subcutaneously (n = 48). A high degree of cross-reactivity between neutralizing anti-IFN-beta-1a and -1b antibodies was observed. No effect of NABs on clinical outcome could be detected in this limited material. Binding anti-IFN-beta antibodies were observed in 20% of IFN-beta-1a treated patients compared with 81% of patients treated with IFN-beta-1b. Only one of 17 patients examined (6%) had detectable titres of binding anti-IFN-beta-1b antibodies in the cerebrospinal fluid (CSF). These data are the first using identical methodology to show that IFN-beta-1a gives rise to fewer NABs than IFN-beta-1b at recommended treatment schedules.

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