Analysis of an interferon-gamma gene dinucleotide-repeat polymorphism in Nordic multiple sclerosis patients

The proinflammatory cytokine interferon (IFN)-gamma has been shown to influence the course of multiple sclerosis (MS). The IFN-gamma (IFNG) contains a multiallelic dinucleotide repeat in intron 1. To investigate whether alleles at this locus influence susceptibility to MS, we performed linkage and familial association analyses on 100 sibling pairs from four Nordic countries, and case-control association analysis on 220 intermediately disabled sporadic MS patients and 266 controls. To determine the effect of the polymorphism on disease outcome, we compared genotype frequencies in the most and least disabled octiles of a total cohort of 913 cases. We also measured IFN-gamma mRNA levels in unstimulated peripheral blood mononuclear cells from 46 MS patients and 27 controls grouped according to IFNG intron 1 genotype. Both nonparametric linkage analysis and transmission disequilibrium testing of the 100 sibling pairs produced negative results. Genotype frequencies for intermediate-MS patients did not differ significantly from those for controls; nor did genotype frequencies in the benign-MS octile differ significantly from those in the severe-MS octle. Comparison of IFN-gamma mRNA levels in genotype-conditioned subgroups revealed no significant differences. Thus, alleles at the IFNG intron 1 dinucleotide repeat appear to affect neither MS susceptibility and severity nor IFN-gamma mRNA expression in vivo.     

Humoral immune responses within the human central nervous system following systemic immunization

We investigated sequential humoral immune responses in the CSF and blood of 6 stable multiple sclerosis (MS) patients without decreases in the blood-brain barrier. Anti-tetanus toxoid antibodies (anti-TT Ab) increased to a similar relative degree within the CSF and blood starting within 2 weeks after subcutaneous booster injection of TT. In 3 of 4 subjects, CSF lymphocytes obtained at 2 weeks secreted anti-TT Ab to the same degree as autologous blood lymphocytes when cultured with pokeweed mitogen. These findings suggest a prompt antibody response within the CSF to systemically administered antigen, not due to diffusion from the serum, with active trafficking of TT-sensitized lymphocytes into the central nervous system.     

Linkage analysis of a candidate region in Scandinavian sib pairs with multiple sclerosis reveals linkage to chromosome 17q

To date, four genome screens have been completed in the demyelinating autoimmune disease multiple sclerosis (MS). Although these screens failed to identify any loci with major effects on susceptibility, several novel regions of potential linkage were suggested, including the long arm of chromosome 17. In order to further pursue this promising region we have investigated six highly polymorphic microsatellite markers in 115 Scandinavian families with MS affected sib pairs. Multipoint linkage analysis revealed a peak maximum likelihood score (MLS) of 0.9 in the region of marker D17S787. Stratifying the results on the basis of HLA-DR2 status showed that the linkage was not limited to families segregating for the HLA-DR2 allele as has previously been suggested. In conclusion, our results further support the proposal that a multiple sclerosis susceptibility locus is contained on chromosome 17q.     

A genome-wide screen for linkage in Nordic sib-pairs with multiple sclerosis

Genetic factors influence susceptibility to multiple sclerosis but the responsible genes remain largely undefined, association with MHC class II alleles being the only established genetic feature of the disease. The Nordic countries have a high prevalence of multiple sclerosis, and to further explore the genetic background of the disease, we have carried out a genome-wide screen for linkage in 136 sibling-pairs with multiple sclerosis from Denmark, Finland, Norway and Sweden by typing 399 microsatellite markers. Seventeen regions where the lod score exceeds the nominal 5% significance threshold (0.7) were identified-1q11-24, 2q24-32, 3p26.3, 3q21.1, 4q12, 6p25.3, 6p21-22, 6q21, 9q34.3, 10p15, 10p12-13, 11p15.5, 12q21.3, 16p13.3, 17q25.3, 22q12-13 and Xp22.3. Although none of these regions reaches the level of genome-wide significance, the number observed exceeds the 10 that would be expected by chance alone. Our results significantly add to the growing body of linkage data relating to multiple sclerosis.     

Serological differences in monozygotic twin pairs discordant for multiple sclerosis

OBJECTIVES: The etiology of MS is unknown but genetic factors are supported by a high concordance in twins. Geographic distribution and migration studies indicate, however, the importance of environmental factors. MATERIAL AND METHODS: We studied 3 pairs of genetically identical twins who had shared the same environment but were discordant for MS. Serum samples were assayed for antibodies against 21 viruses, 4 bacteria and Toxoplasma gondii. RESULTS AND CONCLUSION: No common factor present only in the affected twins was identified but differences were found in serum titers against some neurotropic microorganisms. In general the serum titers were strikingly similar in the twins, indicating no major disturbances of the humoral immune system in MS.     

Analysis of a predominant immunoglobulin population in the cerebrospinal fluid of a multiple sclerosis patient by means of an anti-idiotypic hybridoma antibody.

We have produced hybridoma antibodies directed against immunoglobulins present in the cerebrospinal fluid of a patient with multiple sclerosis (MS). One hybridoma antibody recognized an idiotypic determinant of an immunoglobulin population [an idiotype (Id)] which constituted approximately 1% of the immunoglobulin present in the cerebrospinal fluid. The Id focused in the pH range 8.0-8.4. It was present at roughly 10- to 15-fold higher relative (compared to total immunoglobulin) concentration in cerebrospinal fluid than in serum of the homologous MS patient. The Id could not be detected in three cerebrospinal fluid samples and 28 serum samples of heterologous MS patients or in the serum of 43 optic neuritis patients. The Id persisted in the homologous MS patient at increased concentration over the entire (6 years) observation period. The Id could be shown to react with a Theiler murine encephalomyelitis virus strain WW which was isolated from mice after inoculation with periplaque white matter from brain in a histologically confirmed case of MS.     

HL–A HISTOCOMPATIBILITY ANTIGENS IN OPTIC NEURITIS

HL-A and MLC typing in 54 patients with optic neruitis showed increased frequencies of the HL-A3, 7 and LD-7a determinants of approximately the same magnitude as in patients with multiple sclerosis. The frequencies of the same three determinants were not different in the 11 patients who developed multiple sclerosis during the period of follow-up compared to the remaining patients. There was a significant increase in the frequency of the HL-A3 determinant in patients with oligoclonal IgG of the cerebrospinal fluid at the onset of disease. The connection between this determinant and the occurrence of cerebrospinal fluid changes is not clear. The results suggest that optic neuritis and multiple sclerosis represent different aspects of the same disease entity, rather than two distinct diseases. HL-A and MLC typing did not seem to offer prognostic information as to the later development of multiple sclerosis in these patients, but the observation period is still short.     

Enhanced benefit of increasing interferon beta-1a dose and frequency in relapsing multiple sclerosis: the EVIDENCE Study

BACKGROUND: The EVIDENCE (Evidence of Interferon Dose-Response: European North American Comparative Efficacy) Study demonstrated that patients with multiple sclerosis (MS) who initiate interferon beta-1a therapy with 44 microg 3 times weekly (TIW) were less likely to have a relapse or activity on magnetic resonance imaging (MRI) compared with those who initiate therapy at a dosage of 30 microg 1 time weekly (QW). OBJECTIVE: To determine the effect of changing the dosage from 30 microg QW to 44 microg TIW in this extension of the EVIDENCE Study. DESIGN/PATIENTS: Patients with relapsing MS originally randomized to interferon beta-1a, 30 microg QW, during the comparative phase of the study changed to 44 microg TIW, whereas patients originally randomized to 44 microg TIW continued that regimen. Patients were followed up, on average, for an additional 32 weeks. MAIN OUTCOME MEASURE: The within-patient pretransition to post-transition change in relapse rate. RESULTS: At the transition visit, 223 (73%) of 306 patients receiving 30 microg QW converted to 44 microg TIW, and 272 (91%) of 299 receiving 44-microg TIW continued the same therapy. The post-transition annualized relapse rate decreased from 0.64 to 0.32 for patients increasing the dose (P<.001) and from 0.46 to 0.34 for patients continuing 44-microg TIW (P = .03). The change was greater in those increasing dose and frequency (P = .047). Patients converting to the 44-mug TIW regimen had fewer active lesions on T2-weighted MRI compared with before the transition (P = .02), whereas those continuing the 44-microg TIW regimen had no significant change in T2 active lesions. Patients who converted to high-dose/high-frequency interferon beta-1a therapy had increased rates of adverse events and treatment terminations consistent with the initiation of high-dose subcutaneous interferon therapy. CONCLUSIONS: Patients receiving interferon beta-1a improved on clinical and MRI disease measures when they changed from 30 microg QW to 44 microg TIW.     

No evidence for genetic linkage between development of multiple sclerosis and components of the IFN system and the JAK-STAT pathway

Multiple sclerosis (MS) is an inflammatory, demyelinating disease of the central nervous system (CNS). Several observations suggest that the interferon system may be of interest in the study of MS development To investigate whether polymorphism in components of the IFN system and the JAK-STAT pathway influence susceptibility to MS, we performed a linkage analysis between polymorphic loci in or close to the IFN gamma, IFN gamma receptor, IFN alpha/beta receptor, JAK 1, STAT 1 and STAT 3 genes in 27 Swedish families with at least two members having MS. Tests for transmission disequilibrium and nonparametric linkage analysis gave negative results. We found no evidence for linkage between MS and any of these loci.