The lymphoproliferative response to measles virus in twins with multiple sclerosis

Viruses, virulence and pathogenicity

Pathogenicity is a complex process with stringent requirements of both the host cell and the infecting virion. Among these requirements are a port of entry into host cells, a means of replication for the virus, and a means by which infection damages host cells. Damage to the host can result from multiple mechanisms including transformation, suppression of cellular metabolism, apoptosis, autoimmune responses directed against infected or uninfected tissues, or by molecular mimicry. In the attempt to identify new associations between viral infection and disease, investigators should be mindful that variable host factors as well as viral infection may be required for pathogenesis. Efforts to associate specific viral infections with specific diseases may be obscured by final common pathways through which multiple agents damage host cells in similar ways.

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 less than 0.00001) or ODC (p less than 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 depression of measles virus-specific CTL which suggests that this virus-specific immune dysfunction may play a role in the pathogenesis of this disorder.