Impaired measles virus-specific cytotoxic T cell responses in multiple sclerosis

To assess whether an virus-specific immune defect may be associated with multiple sclerosis (MS), we have examined the ability to generate measles virus- and influenza virus-specific cytotoxic T cells (CTL) in patients with MS, normal individuals, and other disease controls (ODC). The mean (± SEM) measles virus-specific CTL response for normal individuals and ODC was 26.9 ± 2.9% (N = 17) and 26.7 ± 2.8% (N = 13) specific lysis, respectively. In contrast, the capacity of MS patients to generate measles virus-specific CTL was markedly diminished. Peripheral blood lymphocytes from MS patients stimulated with measles virus lysed their measles virus-infected autologous B cell line at a group mean level of 6.0 ± 1.4% (N = 16) specific lysis. MS patients had significantly lower measles virus-specific CTL responses than normal individuals (p <0.00001) or ODC (p <0.0001). Importantly, this lowered response did not reflect a generalized depressed cytolytic activity of MS patients, since influenza virus-specific CTL and NK activity from these patients were comparable to normals and ODC. Thus, in MS there is a significant depressing of measles virus-specific CTL which suggests that this virus-specific immune dysfunction may play a role in the pathogenesis of this disorder.