Natural killer cell activity in multiple sclerosis.

Abstract

Abstract Twenty patients with multiple sclerosis (MS) and 20 age- and sex-matched controls were studied for natural killer (NK) cell activity against 3 different target cell lines: Hela, K562, and M-Hela (a Hela strain persistently infected with measles virus). The MS patients had less natural killing against M-Hela than did the control population (mean NK ± SE for controls = 34.3 ± 4.9; for MS = 22.7 ± 2.9; p < 0.05), whereas NK activity was not significantly different between the 2 groups when tested against K562 (controls = 43.5 ± 4.4; MS = 36.2 ± 4.2; p = 0.2). There were no differences between MS patients and controls in the number of circulating NK cells as defined by the presence of avid Fc receptors for IgG. In addition, there was no difference in antibody-dependent cell-mediated cytotoxicity against M-Hela between the 2 groups (controls = 21.6 ± 4.1; MS = 17.5 ± 2.4; p > 0.5). Serum levels of measles antibody were higher in MS patients than in controls, although there was no correlation between NK activity against M-Hela or K562 and the level of antimeasles antibody. The presence of the A3,B7 histocompatibility antigens was associated with decreased natural killing against M-Hela in the MS group (A3,B7 positive = 14.0 ± 2.2; A3,B7 negative = 28.3 ± 4.7; p < 0.02) but not in healthy controls (A3,B7 positive = 25.4 ± 3.4; A3,B7 negative = 24.6 ± 5.9; p > 0.9). Interferon could not be detected in sera from any MS patient or control or in the CSF from a different group of MS patients. These results suggest that a qualitative defect in natural killing may exist in MS; that this defect may be selective, involving reactivity against some target cell lines and not others; and that this defect is predominantly found in patients of the A3,B7 histocompatibility type.