Multiple sclerosis in the Orkney and Shetland Islands. V: The effect on viral titres of histocompatibility determinants

MS and infections-Abandoned and surviving hypotheses

In this introduction, we follow the ups and downs of infections in MS pathogenesis. Our arguments focus on specific agents and events, not referring to general MS epidemiology. The historical approach continues on to contemporary data and a critical analysis.

Genome-wide homozygosity and multiple sclerosis in Orkney and Shetland Islanders

There is strong evidence for both genetic and environmental risk factors comprising the aetiology of multiple sclerosis (MS). While much progress has been made in recent years in identifying common genetic variants using genome-wide association studies, alternative approaches have remained relatively neglected. The prevalence of MS in Orkney and Shetland is among the highest in the world. Previous studies have suggested that a higher degree of parental relatedness in these isolated communities may contribute to the high rates of MS, indicating that recessive effects have an important role in MS aetiology. The Northern Isles Multiple Sclerosis (NIMS) study investigated the potential role of genome-wide homozygosity in MS risk by genotyping 88 MS patients, 89 controls matched by age, sex and ancestry, and a further 89 controls matched for sex and ancestry, but passed the majority of lifetime risk of developing MS (>70 years of age). Three participants were removed on the basis of pedigree-genomic anomalies (n=263). Three measures of genome-wide homozygosity were generated for each individual, and association with MS was assessed using logistic regression models. No effect of genome-wide homozygosity was detected, indicating that inbreeding and consanguinity are not risk factors for MS in this population.

Viral antibody titers, immunogenetic markers, and their interrelations in multiple sclerosis patients and controls

Our purpose was to investigate possible interrelations between antibody titers against seven viruses (measles, rubella, herpes simplex, mumps, varicella-zoster, coronavirus, cytomegalovirus), HLA-class II antigens, and immunoglobulin Gm allotypes in multiple sclerosis (MS). We studied 57 MS patients and 59 controls with similar age and sex distributions. In MS patients, we found the classical increased frequency of HLA-DR2, HLA-DQw1 and also an excess of Gm (3; +/- 23; 5*). Mumps antibody levels were higher in MS patients than in controls; elevation was not significant for measles antibodies. Analysis suggests that an association between HLA-DQw1 and antibody titers against various viruses exists in controls but is absent in MS patients. In particular, we found that mumps antibody titers were higher in DQw1-positive than in DQw1-negative controls, while there was no significant difference among MS cases. Accordingly, we found that the overall difference between patients and controls was due to the fact that DQw1-positive patients had higher titers than controls, while DQw1-negative cases had similar titers as controls. These findings suggest that biological and molecular characteristics of DQw1 might differ in MS patients.

Anti HTLV-I antibodies and HLA phenotypes in the West Indies

Sera of supposedly healthy blood donors were screened for the presence of anti HTLV-I p24 antibodies, and HLA typing for A, B, C and DR antigens was performed for 68 seropositive subjects and 92 seronegative controls. HLA phenotypes of the two groups were not significantly different but the level of the antibody response was related to the antigens of the HLA-B (P = 0.02) and -C loci (P = 0.003). Subjects with HLA-B12 or -B21 antigens had lower titres than the others. Subjects with HLA-Cw2 or -Cw7 antigens had higher titres than the others, but only the difference between HLA-B12 positive and negative subjects (P = 0.002) remained significant at the alpha = 0.10 level if the classical, although conservative, Bonferroni procedure was used to correct for the number of comparisons performed.

Cell-mediated immunological status in multiple sclerosis patients

In vitro lymphocyte proliferation in response to allogeneic pooled cells, mitogens (PHA, Con A and PWM), and PPD was measured in 67 patients with clinically definite MS and in 67 age and sex-matched controls. Overall, dose-response curves in the two groups were similar, but response to PHA and PWM was significantly greater among patients, and a greater percentage of patients failed to respond to peak and suboptimal PPD concentrations. There was a reduced response to allogeneic pooled cells in Dw2 positive controls, and, in both patients and controls, a tendency towards a higher PPD response in Dw2 positive males. The results suggest that there is some alteration of balance of immune regulation in MS, which is slightly affected by Dw2 status.

The genetic contribution to multiple sclerosis. Evidence from North-East England

A study of 206 patients with multiple sclerosis in the north-east of England and their families shows no evidence of monogenic involvement in the disorder. Much more likely is a multifactorial etiology in which the genetic component is polygenic. On this model the heritability is calculated at 52.1% or 40.9% if age variation in incidence is allowed for. The genetic component is present but no more then moderate in extent.

Multiple sclerosis in the Orkney and Shetland Islands. II: The search for an exogenous aetiology

In Orkney and Shetland, a survey of lifetime events was undertaken in multiple sclerosis patients and two control groups to define shared exposure to an exogenous agent or environmental insult. Analyses of demographic factors, diet, social class and occupation, housing and environment, animal exposure, schooling, travel, infectious disease, and medical history disclosed a remarkable similarity in responses between patients and controls for a majority of questions. However, differences were noted for sanitation, place of residence at onset, and animal exposure. The data give additional support for an exogenous aetiology of multiple sclerosis.