Primarily chronic progressive and relapsing/remitting multiple sclerosis: two immunogenetically distinct disease entities

[Genetic aspects in multiple sclerosis. II: HLA system]

Review of studies about HLA antigens and multiple sclerosis (MS). The HLA system, in special class II antigens, subregions DR and DQ, is probably involved in the immunopathogenesis of MS. Haplotype DRB1*1501.DQA1*0102.DQB1*0602, corresponding to phenotype DR2.Dw2.DQ6, is positively associated with MS in several caucasoid populations. Clinical heterogeneity of MS, as well as different diagnostic criteria adopted by investigators are potential sources of confusion and may lead to discrepant results. A better standardization of clinical and laboratorial methodology, appropriate subdivision of patients with different clinical forms of MS, may allow a more accurate evaluation of the role of genetic factors in the pathogenesis of MS.

Distribution of HLA-Dw2 in optic neuritis and multiple sclerosis indicates heterogeneity

The human leukocyte antigen (HLA) phenotype Dw2 is known to be increased in multiple sclerosis (MS), but only slightly in optic neuritis (ON).

MATERIAL AND METHODS

127 consecutive patients with unilateral monosymptomatic ON were typed genomically for HLA-DR and -DQ genes.

RESULTS

The frequency of HLA-Dw2 among ON patients (47%) was found to be significantly higher than among 250 controls (30%) but significantly lower than in a group of 245 MS patients (60%), all of the same ethnic origin. At the group level, these figures can be calculated to indicate that 53% of the ON patients belong to the group of "MS-type ON" (95% confidence limits 25-78%). A compilation of published data on the frequency of the HLA-DR17(3), DQ2 haplotype, prompted by a slight increase in this material, revealed a significant association with this haplotype in ON, after compensation for the increase of Dw2.

CONCLUSION

ON differs from both MS and controls regarding HLA-Dw2. Thus, a substantial number of patients with ON may suffer from conditions not immuno-genetically related to MS, which might be designated as non-MS type ON. This condition may be more common in men and in young patients of both sexes.

Genetics of demyelinating diseases

Multiple sclerosis (MS), the prototypic demyelinating disease in humans, is the most common cause of acquired neurological dysfunction arising between early to mid adulthood. MS is an inflammatory disorder and is believed to result from an autoimmune response, directed against myelin proteins and perhaps other antigens, resulting in demyelination and dense astrogliosis. A genetic component in MS is indicated by an increased relative risk to siblings compared to the general population (lambda s) of 20-40, and an increased concordance rate in monozygotic compared to dizygotic twins. Association and/or linkage studies to candidate genes have yielded a considerable number of reports showing significant genetic effects for the major histocompatibility complex (MHC), immunoglobulin heavy chain, T cell antigen receptor, and myelin basic protein loci. With the exception of the MHC, however, these results have been difficult to replicate or apply beyond isolated populations. Recently, a multi-analytical genomic screen effort was completed to identify genomic regions potentially harboring MS susceptibility genes. Nineteen such regions were identified. The data confirm the reported genetic effect of the MHC region. However, no single locus generated overwhelming evidence of linkage. These results suggest a multifactorial etiology, including both environmental and multiple genetic factors of moderate effect.

Peptide binding characteristics of the coeliac disease-associated DQ(alpha1*0501, beta1*0201) molecule

Genetic susceptibility to coeliac disease (CD) is strongly associated with the expression of the HLA-DQ2 (alpha1(*)0501, beta1(*)0201) allele. There is evidence that this DQ2 molecule plays a role in the pathogenesis of CD as a restriction element for gliadin-specific T cells in the gut. However, it remains largely unclear which fragments of gliadin can actually be presented by the disease-associated DQ dimer. With a view to identifying possible CD-inducing antigens, we studied the peptide binding properties of DQ2. For this purpose, peptides bound to HLA-DQ2 were isolated and characterized. Dominant peptides were found to be derived from two self-proteins: in addition to several size-variants of the invariant chain (li)-derived CLIP peptide, a relatively large amount of an major histocompatibility complex (MHC) class I-derived peptide was found. Analogues of this naturally processed epitope (MHClalpha46 - 63) were tested in a cell-free peptide binding competition assay to investigate the requirements for binding to DQ2. First, a core sequence of 10 amino acids within the MHClalpha46 - 63 peptide was identified. By subsequent single amino acid substitution analysis of this core sequence, five putative anchor residues were identified at relative positions P1, P4, P6, P7, and P9. Replacement by the large, positively charged Lys at these positions resulted in a dramatic loss of binding. However, several other non-conservative substitutions had little or no discernable effect on the binding capacity of the peptides.

Deficient expression in multiple sclerosis of the inhibitory transcription factor Sp3 in mononuclear blood cells

To evaluate differential gene expression in multiple sclerosis (MS) patients and control subjects, we used differential display to screen for messenger RNAs that are differentially expressed in peripheral blood mononuclear cells from monozygotic twins who are discordant for MS. We identified a 232-bp complementary DNA fragment, present only in material from the normal twin, that exhibited 100% identity with the inhibitory transcription factor Sp3. Oligonucleotide primers corresponding to Sp3 messenger RNA sequences amplified complementary DNA of appropriate size from 83% of control subjects but from only 21% of MS patients (p < 0.001). These results suggest that Sp3 gene transcription is suppressed in peripheral blood mononuclear cells from most MS patients and that other genes whose expression is normally suppressed by Sp3 in immune cells may consequently be overexpressed.

DR2/DQw1 inheritance and haplotype sharing in affected siblings from multiple sclerosis families

Although the human leukocyte antigen DR2/DQw1 allele has been associated with multiple sclerosis, studies of DR2/DQw1 inheritance in multiple sclerosis multiplex families have yielded conflicting results. We examined this question in "high-incidence" families, defined as families with more than 50% of siblings affected. DR2/DQw1 allele frequencies were significantly increased, particularly in mothers and affected siblings (p < 0.0001). The transmission of DR2/DQw1 from both parents was more frequent in affected offspring (p = 0.005). While evidence for segregation of disease with a particular parental allele was lacking in most families, the frequency of haplotype sharing was higher in affected sib pairs (p < 0.01).

Soluble E-selectin in multiple sclerosis: raised concentrations in patients with primary progressive disease

OBJECTIVE

To determine whether concentrations of soluble E-selectin (sE-selectin), an immunological marker of endothelial activation, were correlated with gadolinium-DPTA enhancement on MRI in patients with multiple sclerosis.

METHODS

Serial sE-selectin concentrations were measured in 28 patients with multiple sclerosis undergoing monthly gadolinium (Gd) enhanced MRI of the brain and spinal cord, and in 10 control subjects. C reactive protein (CRP), von Willebrand factor (vWF), and tumour necrosis factor-alpha (TNF alpha) were also determined.

RESULTS

Primary progressive patients had significantly increased sE-selectin concentrations compared with the relapsing remitting and secondary progressive patients who had normal sE-selectin concentrations (22.2 (SD1 6.1) ng/ml v 9.8 (SD2.1) ng/ml and 7.7 (SD2.7) ng/ml, respectively, P = 0.03). This difference was attributable to five of the 10 primary progressive patients who had persistently raised sE-selectin concentrations, with relatively inactive MRI studies. No correlation could be found between sE-selectin concentrations and Gd enhancement on MRI, but a close correlation existed between mean concentrations of sE-selectin and TNF alpha (r = 0.71, P < 0.001). Despite raised sE-selectin and TNF alpha concentrations, primary progressive patients had normal CRP concentrations (1.03 (SD1.14) mg/l), which were significantly lower than the relapsing remitting (3.16 (SD2.54) mg/l) and secondary progressive patients (2.28 (SD2.1) mg/l, P = 0.03). Raised CRP concentrations did correlate with infectious episodes, clinical relapse, and Gd enhancement, and were significantly raised when no MRI activity was found. Concentrations of vWF were normal in all patient groups.

CONCLUSIONS

The results further high-light the differences between patients with primary progressive and those with relapsing remitting/secondary progressive multiple sclerosis.

CSF oligoclonal bands, MRI, and the diagnosis of multiple sclerosis

In this retrospective study, the results from investigations (MRI, evoked potentials, alkaline oligoclonal bands [OBs] in CSF) in 94 patients with clinical suspicion of demyelinative disease were evaluated to assess their impact on diagnosis. Forty-three patients were diagnosed as having definite MS, 10 probable MS, and 9 possible MS. MRI findings strongly suggestive of MS were evident in 52/62 (84%) patients, while 47/62 (76%) patients demonstrated OBs in their CSF. In 63% of patients both abnormalities were present. Patients with no OBs in their CSF were on the average older, were more often male, had experienced their first symptoms at a later age, and suffered more often from the chronic-progressive form of the disease than those with a positive CSF finding.

Clinical and subclinical neurological involvement in children of conjugal multiple sclerosis patients

We report the occurrence of clinically definite multiple sclerosis in an offspring of a couple with conjugal multiple sclerosis. Extensive investigation of all members of this family, which includes two additional asymptomatic children, eliminated the possibility of alternative neurological diagnoses. All family members were studied with magnetic resonance imaging (MRI), evoked potentials, and human leukocyte antigen (HLA) typing. An asymptomatic child had subtle white matter abnormalities on MRI, suggesting subclinical neurological involvement. This study documents the third case of multiple sclerosis in the child of conjugal multiple sclerosis patients and provides the first report of MRI lesions in an asymptomatic offspring of the same parents. Neurodiagnostic and immunogenetic investigations of such rare family clusters may contribute to the elucidation of the pathogenesis of multiple sclerosis.

Polymorphic structural features of modelled HLA-DQ molecules segregate according to susceptibility or resistance to IDDM

The structural features of HLA-DQ alleles which are susceptible and resistant to insulin-dependent diabetes mellitus (IDDM) have been examined using a model of their three-dimensional structure obtained by energy minimisation, based on the published structure of HLA-DR1. The model shows DQ molecules to have an overall shape nearly identical to that of DR molecules, but with significant differences in the fine structure: 1) the antigen-binding groove of DQ molecules has a polymorphic first pocket; this pocket can be either amphiphilic or hydrophilic, 2) The beta 49-56 dimerisation domain of DQ is polymorphic: hydrophobic, or amphiphilic, or hydrophilic and positively charged, leading to spontaneous or T-cell receptor-induced homodimer formation, or T-cell receptor-induced homodimer formation, or difficulty of the formation of such dimers, respectively; 3) a prominent Arg-Gly-Asp loop is formed by some DQ alleles (beta 167-169) and probably functions in cell adhesion. There are also small differences in the residues and sequences implicated in CD4 binding (mostly in DQ beta 134-148) but the significance of these differences cannot be evaluated at present. All seven DQ alleles which confer susceptibility to IDDM possess a hydrophilic first pocket in the antigen-binding groove, a hydrophobic or amphiphilic beta 49-56 dimerisation patch that allows for spontaneous or T-cell receptor-induced dimerisation, and the Arg-Gly-Asp loop. By contrast, in the protective alleles at least one of these three features is absent. This segregation of phenotypes according to susceptibility or resistance can well explain the model of tighter autoantigen binding by the protective alleles compared to the susceptible alleles, previously proposed for the pathogenesis of IDDM.

A brain MRI study of different types of chronic-progressive multiple sclerosis

INTRODUCTION

This study was performed to define the pattern of brain magnetic resonance imaging (MRI) abnormalities in chronic-progressive MS (MS).

MATERIAL AND METHODS

Brain MRIs were obtained for 17 patients with secondary progressive MS (SPMS), 14 with primary progressive MS (PPMS) and 5 with "transitional" progressive MS (TPMS).

RESULTS

Total lesion loads were different for the three groups of patients (p < 0.01). At post-hoc analysis, there was no difference between patients with TPMS and those with PPMS, while both these groups had lesion loads lower than those of patients with SPMS. Patients with PPMS with clinical signs indicating involvement of both brain and spinal cord had greater total lesion loads than those with clinical isolated spinal cord involvement (p < 0.05).

CONCLUSION

These data indicate that brain MRI patterns of abnormalities are related to the clinical manifestations in patients with chronic-progressive MS.

Molecular mimicry in T cell-mediated autoimmunity: viral peptides activate human T cell clones specific for myelin basic protein

Structural similarity between viral T cell epitopes and self-peptides could lead to the induction of an autoaggressive T cell response. Based on the structural requirements for both MHC class II binding and TCR recognition of an immunodominant myelin basic protein (MBP) peptide, criteria for a data base search were developed in which the degeneracy of amino acid side chains required for MHC class II binding and the conservation of those required for T cell activation were considered. A panel of 129 peptides that matched the molecular mimicry motif was tested on seven MBP-specific T cell clones from multiple sclerosis patients. Seven viral and one bacterial peptide efficiently activated three of these clones. Only one peptide could have been identified as a molecular mimic by sequence alignment. The observation that a single T cell receptor can recognize quite distinct but structurally related peptides from multiple pathogens has important implications for understanding the pathogenesis of autoimmunity.

Multivariate analysis of predictive factors of multiple sclerosis course with a validated method to assess clinical events

The clinical data of 309 patients with definite multiple sclerosis were recorded in the European data base for multiple sclerosis (EDMUS) to determine the prognostic significance of several demographic and clinical variables. An interview with closed questions structured according to standardised criteria of disease phases and courses was used to assess the clinical course. The reliability was evaluated by four trained neurologists in a sample of 33 patients with multiple sclerosis. Both the within and between rater agreement on data collection was fair to high for the historical variables (K = 0.33-1). Between rater agreement was more variable for the evaluation of 12 different EDMUS event categories (K = 0.3-0.95). The predictive model for the time to reach a secondary progression showed that an age at onset older than 25 (p = 0.006) and an event at onset followed by disability > or = 3 on the Kurtzke expanded disability status scale (EDSS; p = 0.004) were the most unfavourable clinical variables in 249 patients with relapsing remitting (180) or relapsing progressive (69) courses. In the 69 patients with relapsing progressive disease, the time to reach severe disability (EDSS > or = 6) was negatively influenced by a first interval between attacks shorter than one year, a number of bouts with EDSS > 2 in the first two years of the disease, and involvement of the pyramidal system at onset (p < 0.05). In 60 patients with chronic progressive disease this outcome was negatively influenced by pyramidal, brainstem, and sensory involvement at onset (p < 0.01).

DNA extraction and amplification from Giemsa-stained blood smears

DNA extraction was attempted from Giemsa-stained blood smears on glass slides that had been stored for several years. High molecular weight DNA bands were clearly visible after electrophoresis when DNA was extracted from specimens stored up to 2 years. Specimens more than 4 years old demonstrated a smeared pattern, suggesting degeneration of the DNA, but they could be rescued by PCR amplification using primers of HLA-DQA1 genes. The recovery could be pursued even in 11-year-old specimens.

Immunological aspects of experimental allergic encephalomyelitis and multiple sclerosis

Multiple sclerosis (MS) is the most frequent, demyelinating disease of the central nervous system (CNS) in Northern Europeans and North Americans. Despite intensive research its etiology is still unknown, but a T cell-mediated autoimmune pathogenesis is likely to be responsible for the demyelination. This hypothesis is based both on findings in MS patients and studies of an experimental animal model for demyelinating diseases, experimental allergic encephalomyelitis (EAE). Experiments in EAE have not only demonstrated which myelin antigens are able to induce the demyelinating process but also have determined the characteristics of encephalitogenic T cells, that is, their fine specificity, major histocompatibility complex (MHC) restriction, lymphokine secretion, activation requirements, and T cell receptor (TCR) usage. Based on these findings, highly specific and efficient immune interventions have been designed in EAE and have raised hopes that similar approaches could modulate the disease process in MS. Although the examination of the myelin-specific T cell response in MS patients has shown parallels to EAE, this remains an area of intensive research because a number of questions remain. This review summarizes the important lessons from EAE, examines recent findings in MS, and discusses current concepts about how the disease process develops and which steps might be taken to modulate it.

HLA complement gene polymorphisms in multiple sclerosis. A study on 80 Italian patients

We studied C4A, C4B, and Bf complement gene polymorphisms in 80 Italian patients with multiple sclerosis (MS). We observed a significantly higher frequency of C4AQ0 allele in patients with the relapsing-remitting form of MS than in ethnically homogeneous controls. Restriction fragment length polymorphism analysis by Southern blotting of the C4/CYP21 gene complex showed that a structural gene deletion was present in 45% of patients with the C4AQ0 allele. Our data support the hypothesis that relapsing-remitting MS and primarily chronic progressive MS are immunogenetically distinct diseases; further, complement factor abnormalities typical of autoimmune diseases could influence the pathogenesis of MS.

Genetic susceptibility to multiple sclerosis

Twin studies have established that susceptibility to multiple sclerosis (MS) is partly genetic. Attempts to identify the relevant genetic loci have involved population-based studies, to detect associations between a genetic marker and MS, and family studies, to detect linkage between a putative marker and MS. Most of this genetic work is driven by the view that MS is an autoimmune disease. Thus, the focus has been mainly on genes known to be important in the immune response: human leukocyte antigen (HLA) genes, T-cell receptor genes, and immunoglobulin genes. To date, only the particular HLA-DR2 haplotype that is common in Caucasians can be concluded to be important in MS susceptibility in most populations. Studies of other genetic loci have been few, the data obtained often have been conflicting or controversial, and further studies are needed to clarify the biological significance of these loci in MS. Recommendations for further studies are provided in order to overcome some of the problems that have plagued earlier work in MS such as nonreproducibility of results.

Polymorphism of the tumour necrosis factor beta gene in multiple sclerosis and rheumatoid arthritis

We evaluated the TNF-beta gene polymorphism in two HLA-associated autoimmune diseases, multiple sclerosis (MS) and rheumatoid arthritis (RA). The TNF-beta allele and genotype frequencies were not significantly different in the patient populations, compared to controls. An increased frequency of the TNF-beta*2 allele was observed in HLA-DR2+ vs. HLA-DR2- MS patients. No such association was seen in HLA-DR4+ RA patients.

Multiple sclerosis: multiple etiologies, multiple genes?

Multiple sclerosis is a chronic inflammatory disease characterized by multifocal damage of the central nervous system myelin. Both humoral and cell-mediated immune abnormalities have been observed in patients with multiple sclerosis, but their relation to the demyelination process is not understood. The etiology of the disease is still unknown; however, evidence exists for an interplay between environmental and genetic factors. Several genes are involved in determining the disease susceptibility, at least one of them encoded within human leukocyte antigen gene complex. Other genomic regions coding for components of the immune system or myelin have also been suggested. Clinical, immunological and genetic data suggest that multiple sclerosis may turn out to be a heterogeneous disease. Therefore, molecular genetic dissection of this complex disease should provide important clues to its pathogenesis as well as unravel metabolic pathways for potential therapeutic or preventive strategies. This review will give an overview of recent progress and future challenges in identifying susceptibility genes for multiple sclerosis.

Peptide specificity of anti-myelin basic protein antibodies in patients with acute optic neuritis and the HLA system

Multiple sclerosis (MS) may be an autoimmune disease, partially caused by autoreactivity to myelin basic protein (MBP) and other central nervous system proteins. Acute optic neuritis (ON) is a frequent first symptom of MS. The role of the HLA system in anti-MBP antibody production in ON was investigated employing a restriction fragment length polymorphism system for genomic HLA-DQ and -DR typing and an immunospot assay for the detection of individual cells secreting antibodies to three different synthetic MBP peptides. Thirty-two out of 40 patients (80%) with ON had cells in cerebrospinal fluid secreting anti-MBP peptide antibodies while this occurred in 10/19 patients with other neurological diseases (53%; mainly in patients with inflammatory diseases in the central nervous system). This difference was statistically significant (P = 0.03). None of the three examined peptides were immunodominant in any patient group. It was found, however, that presence of HLA DR15, which is associated with MS, may be associated further with predominant production of antibodies to the MBP amino acids 63-88 in patients with ON (P = 0.002, corrected for multiple comparisons).

HLA and prognosis in multiple sclerosis

The patients of a multiple sclerosis (MS) incidence cohort with 25 years of longitudinal follow-up were typed for HLA-DR and DQ. This type of cohort provides reliable data for gene frequencies and prognostic studies. The influence of sampling bias, mainly due to mortality during the long follow-up, was accounted for. A positive association between MS and DR15,DQ6 was confirmed, but this haplotype did not influence prognosis. There was no difference in haplotype frequency between relapsing-remitting and primary chronic progressive MS. DR17,DQ2 was significantly over-represented in the quartile with the most malignant course. The haplotype DR1,DQ5, which was found rather less frequently in MS patients, also tended to be associated with a poorer prognosis.

Genetic disorders that masquerade as multiple sclerosis

There are many genetic disorders that have signs and symptoms suggestive of multiple sclerosis and that may easily be overlooked in the evaluation of both adult and pediatric multiple sclerosis patients. The recognition of a genetic disorder as the cause of a patient's "multiple sclerosis" phenotype has important implications not only for the patient, but often also for others in the patient's family who may be at risk for the same disease. We present here a review of single gene disorders that can masquerade as multiple sclerosis. For each disorder, the major clinical and biochemical characteristics are discussed, together with the appropriate testing to screen for and confirm the diagnosis. In addition, guidelines are presented for when to suspect an underlying genetic condition in a patient with a diagnosis of definite or probable multiple sclerosis. The great variety of genetic disorders that can masquerade as multiple sclerosis and the many implications of a genetic diagnosis underscore the importance of recognizing genocopies of multiple sclerosis.

Natural history of multiple sclerosis

Multiple sclerosis (MS) is the most common idiopathic inflammatory disease of the central nervous system. The distinction between MS and other benign or fulminant inflammatory demyelinating disorders is based on quantitative, rather than qualitative, differences in chronicity and severity. Primary progressive MS may differ from relapsing-remitting MS in MRI lesion frequency, immunogenetic profile, responsiveness to immunosuppressive treatment, and histology. In 60% of patients, MS begins as a relapsing-remitting disease and evolves secondarily into a progressive neurological illness. Life expectancy is not substantially altered in patients with MS, particularly in the early years of the illness. The rate of suicide has been reported to be increased sevenfold in MS patients. Up to 40% of patients with attacks severe enough to render them nonambulatory may not recover. At 15 years from MS onset, 50% of patients are disabled to the point at which they at least require a cane to walk a half block. Early age at onset, female sex, relapsing-remitting course at onset, and perhaps optic neuritis or sensory symptoms at onset and relatively few attacks in the first two years are associated with a favorable course.

Structural requirements for binding of an immunodominant myelin basic protein peptide to DR2 isotypes and for its recognition by human T cell clones

Immunodominant T cell epitopes of myelin basic protein (MBP) may be target antigens for major histocompatibility complex class II-restricted, autoreactive T cells in multiple sclerosis (MS). Since susceptibility to MS is associated with the DR2 haplotype, the binding and presentation of the immunodominant MBP(84-102) peptide by DR2 antigens were examined. The immunodominant MBP(84-102) peptide was found to bind with high affinity to DRB1*1501 and DRB5*0101 molecules of the disease-associated DR2 haplotype. Overlapping but distinct peptide segments were critical for binding to these molecules; hydrophobic residues (Val189 and Phe92) in the MBP(88-95) segment were critical for peptide binding to DRB1*1501 molecules, whereas hydrophobic and charged residues (Phe92, Lys93) in the MBP(89-101/102) sequence contributed to DRB5*0101 binding. The different registers for peptide binding made different peptide side chains available for interaction with the T cell receptor. Although the peptide was bound with high affinity by both DRB1 and DRB5 molecules, only DRB1 (DRB1*1501 and 1602) but not DRB5 molecules served as restriction elements for a panel of T cell clones generated from two MS patients suggesting that the complex of MBP(84-102) and DRB1 molecules is more immunogenic for MBP reactive T cells. The minimal MBP peptide epitope for several T cell clones and the residues important for binding to DRB1*1501 molecules and for T cell stimulation have been defined.

Skewed T-cell receptor repertoire in genetically identical twins correlates with multiple sclerosis

Although the cause of multiple sclerosis (MS) is unknown, it is thought to involve a T cell-mediated autoimmune mechanism. Susceptibility to the disease is influenced by genetic factors such as genes of the HLA and T-cell receptor (TCR) complex. Other evidence for a genetic influence includes the low incidence in certain ethnic groups, the increased risk if there are affected family members and the increased concordance rate for disease in monozygotic twin pairs (26%), compared to dizygotic twins. Epidemiological studies indicate that there may be an additional role for environmental factors. Although the target antigen(s) are not yet identified, several myelin or myelin-associated proteins have been suspected, among them myelin basic protein. A lack of genetically comparable controls has impaired the analysis of the T-cell response in MS patients and caused disagreement on TCR usage in the disease. Here we analyse the role of TCR genes in MS by comparing TCR usage in discordant versus concordant monozygotic twins in response to self and foreign antigens. We find that after stimulation with myelin basic protein or tetanus toxoid, control twin sets as well as concordant twin sets select similar V alpha chains. Only the discordant twin sets select different TCRs after stimulation with antigens. Thus exogenous factors or the disease shape the TCR repertoire in MS patients, as seen by comparison with unaffected genetically identical individuals. This skewing of the TCR repertoire could contribute to the pathogenesis of MS and other T-cell-mediated diseases.

HLA-DR, -DQ and -DP alleles in nickel, chromium, and/or cobalt-sensitive individuals: genomic analysis based on restriction fragment length polymorphisms

The increased concordance rate of nickel sensitivity in monozygotic compared to dizygotic twins indicates a genetic causal component. We have previously described an association in nickel-sensitive subjects with an HLA-DQA restriction fragment length polymorphism (RFLP) (4.5-kb TaqI band, DQA1*0501). The purpose of the present study was to investigate if our previous finding could be confirmed in an independent study, and also to investigate the distribution of HLA class II alleles in chromium- and cobalt-sensitive individuals. Using TaqI- or MspI-digested DNA and DQA, DQB, DRB, DPA and DPB cDNA probes alleles were defined by RFLP analysis. The association with the DQA1*0501 allele was not confirmed in the new group of 37 nickel-sensitive subjects (compared to 150 new controls), nor when the two groups of patients were combined. The distribution of HLA class II alleles and DR-DQ haplotypes were similar in the pooled group of 70 nickel-sensitive subjects and the combined control groups (n = 250). No significant changes in the distribution of HLA class II allele among the chromium- (n = 26) and/or cobalt- (n = 38) sensitive individuals were found. Our results indicate that it is unlikely that the tendency to develop metal sensitivity is associated with alleles of the HLA class II region.

Interferons in multiple sclerosis. A review of the evidence

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system, characterised clinically by relapses and remissions, and leading eventually to chronic disability. Despite an enormous amount of research, the cause of MS remains unknown; however, pathological, genetic, and immunological features have been identified that suggest the disease has an autoimmune basis. Accordingly, current therapy of MS includes corticotrophin or corticosteroids for acute exacerbations, and more potent immunosuppressive drugs for severe cases unresponsive to steroids. All of these agents can cause serious adverse reactions. There is an urgent need for immunotherapy that is less toxic, that can be given early and perhaps indefinitely, and that will prevent relapses and progression of the disease. Our current knowledge of the effects of interferons (IFNs) in MS is based on the results of laboratory research and clinical therapeutic trials carried out over the past decade. Existing evidence points to the conclusion that the effects of the IFNs in MS are mediated by immunoregulatory rather than antiviral or nonspecific mechanisms. Administration of IFN gamma increases the exacerbation rate, and IFN gamma as well as other cytokines may be involved in the pathogenesis of MS lesions. In contrast, studies of IFN beta show that it tends to inhibit the activity of IFN gamma and appears to prevent disease activity. Intrathecal administration of IFN beta, although effective, is cumbersome and potentially hazardous. A large multicentre placebo-controlled trial of systemic recombinant IFN beta was recently conducted in the US, and the results of the first 2 years of treatment were considered sufficiently encouraging that an application for licensing was submitted to the Food and Drug Administration in June 1992. If approved, it will be the first new agent licensed for clinical use in MS in over 20 years. The study will continue under double-blind conditions for at least another year, and a second trial of systemic recombinant IFN beta therapy is also in progress. These studies should provide definitive answers to questions about the role of IFNs in the pathogenesis of MS, as well as the place of recombinant IFN beta as an effective therapeutic agent.

Shared HLA class II-associated genetic susceptibility and resistance, related to the HLA-DQB1 gene, in IgA deficiency and common variable immunodeficiency

Most cases of selective IgA deficiency (IgA-D) and common variable immunodeficiency (CVID) occur sporadically. However, familial clustering is not uncommon, and the two disorders can occur within the same family. We have previously described positive associations with three DR-DQ haplotypes as well as a strong negative association with DRw15,DQw6,Dw2 in IgA-D. Different amino acids at position 57 of the HLA-DQ beta chain were found to be related to susceptibility and resistance to IgA-D. Now we have found identical, although somewhat weaker, positive and negative DR-DQ associations in a large group of CVID patients (n = 86), as well as the same associations with codon 57 of the DQB1 gene. In addition, we have confirmed our earlier observations in an independent group of IgA-D individuals (n = 69), and in sib-pair analysis we have found linkage of the genetic susceptibility to IgA-D to the HLA class II region. In IgA-D individuals not carrying the three overrepresented DR-DQ haplotypes, the same positive association with a non-aspartic acid residue at position 57 of the HLA-DQ beta chain was seen. The previously reported associations with deletions of the HLA class III genes C4A (fourth component of complement) and CYP21P (steroid 21-hydroxylase pseudogene) were, in our groups of immunodeficient individuals, statistically secondary to the association with the DQB1 allele 0201. The shared HLA class II associations in the two humoral immunodeficiencies support the hypothesis that IgA-D and CVID are related disorders. Disease susceptibility and resistance are most closely associated with a gene(s) within the DR-DQ region, alleles of the DQB1 locus being candidate genes.

An immunogenetic heterogeneity in multiple sclerosis

Two clinical forms of multiple sclerosis (MS), primarily chronic progressive MS (PCP MS) and relapsing/remitting MS (R/R MS) have been shown to differ in several respects. The results of genomic HLA class II typing with restriction fragment length polymorphism analysis of 62 MS patients from Western Norway, 42 with R/R MS and 20 PCP MS, are reported on here. As in previous studies of Swedish patients, the haplotype DRw17(3), DQw2 was found to be five times more common in R/R MS than in PCP MS. This finding supports the hypothesis that R/R and PCP MS are immunogenetically separate entities. In contrast with a previous investigation of Norwegian MS patients, no association of MS with glutamine at position 34 of the HLA-DQ alpha chain or with defined sequences of the HLA-DQB1 gene was found.

HLA class II genes in primary sclerosing cholangitis and chronic inflammatory bowel disease: no HLA-DRw52a association in Swedish patients with sclerosing cholangitis

The familial predisposition to chronic inflammatory bowel disease and the increased concordance rate in monozygotic twins with Crohn's disease, suggest that genetic factors influence disease susceptibility. A 100% association with the supertypic HLA class II specificity DRw52a was recently described in white North American patients with primary sclerosing cholangitis, with or without concurrent ulcerative colitis. HLA class II alleles of the DR, DQ, and DP subregions were determined by genomic typing techniques in a large group of Swedish patients with ulcerative colitis or Crohn's disease as well as in a series of patients with primary sclerosing cholangitis. No statistically significant HLA class II association was observed in any of the investigated diseases or when the patients were subgrouped according to disease site or occurrence of extraintestinal manifestations, except an insignificant increase of the DRw17, DQw2 haplotype in patients with primary sclerosing cholangitis. The failure to confirm the well established DRw17 association in Swedish patients with sclerosing cholangitis probably represents a statistical type II error. Furthermore, this study did not verify the recently described strong DRw52a association in sclerosing cholangitis--52% of the patients were DRw52a positive compared with 28% of the controls (p less than 0.05, pc NS). This discrepancy was probably caused by different typing techniques. The DRw52a specificity was determined directly by hybridising HLA-DRB3 genes, group specifically amplified by the polymerase chain reaction, with an allele specific oligonucleotide probe, whereas in the previously mentioned study DRw52a was assigned by indirect serological criteria, which overestimate the frequency of this allele.

Different genetic backgrounds for malnutrition-related diabetes and type 1 (insulin-dependent) diabetes mellitus in south Indians

HLA-DRB, -DQA and -DQB genes were studied in ten South Indian malnutrition-related diabetic patients, ten Type 1 (insulin-dependent) diabetic patients and 45 control subjects, by TaqI restriction fragment length polymorphism analysis. The DR7,DQw9 haplotype was found to be frequent in patients with malnutrition-related diabetes (p less than 0.01). The DRw17,DQw2 haplotype was overrepresented in the patients with Type 1 diabetes compared to control subjects (p less than 0.05). In vitro amplification of the polymorphic second exon of DQB genes by the polymerase chain reaction technique was performed on DNA from 10 malnutrition-related diabetic patients, 10 Type 1 diabetic patients and 13 control subjects, as they belong to a new population. Hybridization with sequence-specific oligonucleotide probes for DQB1 alleles showed homozygosity of aspartic acid at position 57 in 7 of 10 malnutrition-related diabetic patients compared to 2 of 10 Type 1 diabetic (p less than 0.05) and 15 of 45 control subjects (p less than 0.05). Homozygosity of non-aspartic acid at position 57 was present in 7 of 10 Type 1 diabetic compared to 0 of 10 malnutrition-related diabetic patients (p less than 0.005) and 3 of 45 control subjects (p less than 0.05). This study has confirmed the association of DQB1 57 non-asp in South Indians with Type 1 diabetes. In addition, our data clearly show that the genetic background of malnutrition-related diabetes mellitus is different from that of Type 1 diabetes.

Early prognostic factors for disability in multiple sclerosis, a European multicenter study

The effects of initial clinical variables on short-term prognosis are analyzed in a cross-sectional study of 574 multiple sclerosis patients from 7 centers in 5 European countries. Patients with a primary progressive course had a 2.3 higher mean disability score (EDSS) than the primary remittent group after a mean duration of disease of 6.6 years. High age at onset was associated with a primary progressive course, and was also related to increased risk of a rapid shift to a secondary progressive course. Among the remittent patients without a secondary progressive course a high age at onset was significantly correlated to a higher disability score. In the whole remittent group the presence of pyramidal and cerebellar symptoms at onset predicted both a high disability score and a rapid shift to a secondary progression, while the effect was reverse for sensory and visual symptoms. No difference between the sexes was found.

Novel HLA-DR2-related haplotypes in Hong Kong Chinese implicate the DQB1*0602 allele in susceptibility to multiple sclerosis

Multiple sclerosis (MS) is strongly associated with the HLA-Dw2 haplotype DRw15.DQw6 in Caucasoids, although the relative contributions of DR and DQ loci to disease susceptibility are unknown. The situation is further complicated by the apparent lack of an association between DR2 and MS in Orientals. This study examined 42 DR2-positive chromosomes in healthy Chinese and 12 DR2-positive chromosomes in MS patients from Hong Kong, using oligonucleotide hybridizations of DQA1, DQB1, DRB1, and DRB5 polymerase chain reaction (PCR) products. There was marked heterogeneity in DR2-related haplotypes in controls (ten types), where the most frequent haplotype, confirmed in one family, involved the novel arrangement DRB1*1501, DQB1*0601. Another common haplotype had the unusual combination of DRB1*1602, DRB5*0101 as confirmed by DNA sequencing of the DRB5 allele. In contrast, the most common DR2-related haplotype in MS patients was the 'classical' Dw2 haplotype DRB1*1501, DQB1*0602, with a frequency of 50% compared with 12% in controls (P = 0.01). Novel DR,DQ linkage disequilibrium relationship in Hong Kong Chinese have permitted recognition of DQB1*0602 as a susceptibility allele in DR2-positive MS patients, although a role for the DRB1*1501 allele in MS pathogenesis has not been excluded by this study.

HLA-DR and -DQ gene polymorphism in West Africans is twice as extensive as in north European Caucasians: evolutionary implications

The HLA genes are the most polymorphic coding loci known in humans. DRB-DQA-DQB gene polymorphism was investigated by Taq I restriction fragment length polymorphism analysis in more than 700 West Africans and found to be almost twice as extensive in West Africans as in North European Caucasians. This finding indicates that Africans comprise the oldest and genetically most diverse human population and supports the hypothesis of the occurrence of a population bottleneck in the emergence of the White race. As in Caucasians, less than one-third of possible cis-encoded DQA-DQB combinations were encountered, indicating constraints on the pairing of DQ alpha and beta polypeptides. Heterozygote advantage (i.e., positive selection) was found for DRB, DQA, and DQB alleles as well as for DQA-DQB combinations. However, in West Africans as well as in North Europeans the observed frequencies of DRB-DQA-DQB homozygotes were close to neutrality expectations. Although the hypothesis that HLA polymorphism is maintained by parasite-driven overdominant selection is attractive, there is little evidence to support that view. We propose instead that one of the forces maintaining a low frequency of HLA homozygotes might be a decreased likelihood of potentially autoreactive T-cell clones escaping thymic selection in HLA heterozygotes. This would be consistent with the central role of HLA molecules as self/non-self discriminators.

Sclerosis multiplex in gypsies

MS rarely occurs in gypsies in Hungary despite the high DR2 frequency. When it does occur, it has special features more resembling that of Asians than Central Europeans. In order to find correlation between the clinical observations and the immunogenetical data, the distribution of DQw1 subtypes was investigated by means of Eco RV - DQ beta RFLP in DR2 positive healthy gypsies and Hungarians, as well asin DR2-positive Hungarian and unselected gypsy MS patients. DQw6 correlated with MS susceptibility in Hungarians. This allotype was completely absent in healthy DR2-positive gypsies. DR2-positive gypsy MS patients, however, carried DQw6. No correlation of complement allotypes with the occurrence of MS was found in Hungarians, while a striking elevation of C4 Q0 occurred in gypsy MS patients compared with healthy individuals in the gypsy group. The absence of the DR2, DW2, DQw6 haplotype, and the frequency of C4A Q0 in healthy gypsies seems to be associated with the low MS prevalence, but genes outside this region might also influence the MS susceptibility.

HLA class II-associated genetic susceptibility in multiple sclerosis: a critical evaluation

Multiple sclerosis (MS) has, since the 1970s, been known to be associated with the HLA-Dw2 and -DR2 specificities in Caucasian Europeans and North Americans. By the use of genomic typing techniques, the association has been specified to be with the DRw15,DQw6,Dw2, i.e. the DRB1*1501-DQA1*0102-DQB1*0602 haplotype. A significant DPw4 association in Scandinavian MS patients has been described in one report. However, this association has not been confirmed in several subsequent studies with patients from the same and other ethnic groups. During the last few years several reports, based on serological, RFLP and PCR-SSO data, have suggested that the HLA class II-associated MS susceptibility gene(s) may be more closely associated with the DQ than with the DR subregion. The observations that the HLA-DQB1 genes of MS patients share long stretches of sequence motifs and also carry DQA1 alleles encoding glutamine at position 34 of the DQ alpha chain have received considerable attention. It has been suggested that the susceptibility to develop MS might be determined by the corresponding DQ alpha-beta heterodimers either encoded in cis or in trans. We have investigated these issues in a large group of Swedish MS patients (n = 179). We found that the associations with the suggested DQB1 sequences and position 34 of the DQ alpha chain were due to linkage disequilibrium and secondary to the association with the DRw15,DQw6,Dw2 haplotype (p less than 10(-9) and p less than 10(-8), respectively). No overrepresentation of the implicated DQ alpha-beta heterodimers was observed in DRw15,DQw6,Dw2-negative patients.(ABSTRACT TRUNCATED AT 250 WORDS)

HLA-DRB1*01 subtyping by allele-specific PCR amplification: a sensitive, specific and rapid technique

The two DR1-associated cellular specificities Dw1 and Dw20, as well as DR'Br' (Dw'BON'), cannot be unequivocally assigned by serological typing or restriction fragment length polymorphism (RFLP) analysis. We have developed and compared two polymerase chain reaction-based (PCR) typing methods for distinguishing these DRB1 alleles; allele-specific amplification of DRB1*01 alleles followed by an agarose gel electrophoresis detection step and group-specific DRB1*01 amplification followed by hybridization with sequence-specific oligonucleotide probes. The two typing strategies gave completely concordant results in the 33 DRB1*01-positive and the 46 DRB1*01-negative individuals and cell lines studied. No false-negative or false-positive typing results were obtained. All possible heterozygous combinations of the DRB1*0101-0103 alleles could be distinguished by both typing methods. DRB1*01 subtyping by allele-specific PCR amplification was performed in less than 3 hours, including PCR amplification, detection and interpretation steps. The technique will be a valuable complement to DR typing by serology and RFLP analysis. Allele-specific DRB1 amplifications or group-specific amplifications followed by directed allele-specific amplifications of DRB1 alleles, typing based on the absence or presence of amplified products, may well prove to be the technical innovation that will firmly establish PCR-based DR typing in routine clinical tissue typing.

Analysis of HLA-DRB and -DQB gene RFLPs in DR7 homozygous cell lines: associations with Dw11, Dw17 and DB1

The DR7-associated Dw specificities, Dw11, Dw17 and DB1 were investigated with regard to DRB- and DQB-gene polymorphism, as revealed by RFLP analysis using the restriction enzyme TaqI. In the 22 DR7 homozygous cell lines investigated, each of these Dw specificities was found to correlate to one specific RFLP defined DR-DQ haplotype. In addition, a clear linkage disequilibrium to a specific HLA-B locus allele for each Dw specificity was noted, indicating that the Dw subtypes of DR7 often are associated with a conserved HLA-B-DR-DQ haplotype. Only one genetically homozygous cell line, PLH, deviated from these correlations. This cell line, notably derived from an individual with a deletion of the 21-hydroxylase B-gene (21-OHB), caries the HLA haplotype Bw47, DR7, DQw2, DB1, but displayed a DRB RFLP otherwise found in association with Dw17.

Major differences in the dynamics of primary and secondary progressive multiple sclerosis

In patients with primary and secondary progressive multiple sclerosis (MS), major differences in the pattern and extent of abnormality on cerebral magnetic resonance imaging (MRI) between the two groups have recently been demonstrated. In the present study, 24 patients, matched for age, sex, duration of disease, and disability, had serial gadolinium diethylenetriaminepentaacetic acid-enhanced MRI over a 6-month period. The 12 patients in the secondary progressive group had a total of 109 new lesions over this time (18.2 lesions per patient per year) and 87% of these enhanced. Enhancement also occurred within and at the edge of preexisting lesions. In contrast, only 20 new lesions were seen in the primary progressive group (3.3 lesions per patient per year) and only one of these enhanced. There was no difference in the degree of clinical deterioration between the two groups over the 6-month period. These findings may indicate a difference in the dynamics of disease activity between the two forms of progressive MS, particularly in relation to the inflammatory component of the lesions, and have important implications for the selection of patients and the monitoring of disease activity in therapeutic trials.

HLA-DP incompatibilities induce significant proliferation in primary mixed lymphocyte cultures in HLA-A, -B, -DR and -DQ compatible individuals: implications for allogeneic bone marrow transplantation

The major part of the proliferative response in primary mixed lymphocyte cultures (MLC) is caused by HLA-DRB1 incompatibilities. In DRB1-matched pairs the proliferation induced by HLA-DRB3, -DQ and -DP mismatches may be unmasked. In most previous studies the influence of HLA-DP incompatibilities in primary MLC has been investigated in homozygous typing cells representing only a few Dw specificities. We were interested in determining the stimulatory capacity of isolated HLA-DP mismatches, ascertained by RFLP analysis, in primary MLC in HLA-A, -B, -DR and -DQ compatible, unrelated heterozygous individuals of many different Dw specificities. Thirty-eight MLCs performed with cells from related pairs and 67 with cells from unrelated pairs were evaluated. All but nine of the MLCs were analyzed in both directions, giving a total of 201 investigated reactions. The relative responses (RR) in the three MLCs performed between DP incompatible, related pairs were all positive (RR greater than or equal to 8%). Eighty of 82 MLCs performed with cells from DP incompatible, unrelated individuals were positive, whereas 37 of 46 MLCs between DP compatible, unrelated pairs were negative (RR less than 8%) (p less than 10(-10)). The magnitude of the RR was influenced by the number of DP mismatches. Thus, the mean RR was approximately twice as high in MLCs in which responder and stimulator cells differed by two DP antigens (mean RR 60.5%) compared with reactions with only one DP mismatch (mean RR 35.4%) (p less than 10(-3)). RFLP-defined HLA-DP incompatibilities predict a positive primary MLC in HLA-A, -B, -DR and -DQ matched individuals with a high degree of accuracy (98%).(ABSTRACT TRUNCATED AT 250 WORDS)