Design, engineering, and production of human recombinant t cell receptor ligands derived from human leukocyte antigen DR2

Major histocompatibility complex (MHC) class II molecules are membrane-anchored heterodimers on the surface of antigen-presenting cells that bind the T cell receptor, initiating a cascade of interactions that results in antigen-specific activation of clonal populations of T cells. Susceptibility to multiple sclerosis is associated with certain MHC class II haplotypes, including human leukocyte antigen (HLA) DR2. Two DRB chains, DRB5*0101 and DRB1*1501, are co-expressed in the HLA-DR2 haplotype, resulting in the formation of two functional cell surface heterodimers, HLA-DR2a (DRA*0101, DRB5*0101) and HLA-DR2b (DRA*0101, DRB1*1501). Both isotypes can present an immunodominant peptide of myelin basic protein (MBP-(84-102)) to MBP-specific T cells from multiple sclerosis patients. We have previously demonstrated that the peptide binding/T cell recognition domains of rat MHC class II (alpha1 and beta1 domains) could be expressed as a single exon for structural and functional characterization; Burrows, G. G., Chang, J. W., Bächinger, H.-P., Bourdette, D. N., Wegmann, K. W., Offner, H., and Vandenbark A. A. (1999) Protein Eng. 12, 771-778; Burrows, G. G., Adlard, K. L., Bebo, B. F., Jr., Chang, J. W., Tenditnyy, K., Vandenbark, A. A., and Offner, H. (2000) J. Immunol. 164, 6366-6371). Single-chain human recombinant T cell receptor ligands (RTLs) of approximately 200 amino acid residues derived from HLA-DR2b were designed using the same principles and have been produced in Escherichia coli with and without amino-terminal extensions containing antigenic peptides. Structural characterization using circular dichroism predicted that these molecules retained the antiparallel beta-sheet platform and antiparallel alpha-helices observed in the native HLA-DR2 heterodimer. The proteins exhibited a cooperative two-state thermal unfolding transition, and DR2-derived RTLs with a covalently linked MBP peptide (MBP-(85-99)) showed increased stability to thermal unfolding relative to the empty DR2-derived RTLs. These novel molecules represent a new class of small soluble ligands for modulating the behavior of T cells and provide a platform technology for developing potent and selective human diagnostic and therapeutic agents for treatment of autoimmune disease.

[Comparison of HLA class I and DR class II antigen frequency in Polish patients, in relation to different stages of the disease]

The aim of this study was to analyze the association between HLA class I and class II DR frequency in the different stages of sarcoidosis in Polish population. 88 patients and 30 healthy controls have been typed. Patients were divided into three groups depending on radiological findings. In the first group were 28 cases presenting the regression of the disease. In the second were 33 patients in stable stage II or III and in the third group 27 patients with pulmonary fibrosis (stage IV). The typing was performed by NIH method using commercial sera. There were no statistically significant differences between studied group in HLA-A class I. The frequency of HLA B-18 was statistically more frequent in patients with sarcoidosis compared to healthy controls. HLA-DR1 was not present in third group of patients and the difference was significant compared to healthy controls.

Anergy induction by dimeric TCR ligands

T cells that recognize particular self Ags are thought to be important in the pathogenesis of autoimmune diseases. In multiple sclerosis, susceptibility is associated with HLA-DR2, which can present myelin-derived peptides to CD4(+) T cells. To generate molecules that target such T cells based on the specificity of their TCR, we expressed a soluble dimeric DR2-IgG fusion protein with a bound peptide from myelin basic protein (MBP). Soluble, dimeric DR2/MBP peptide complexes activated MBP-specific T cells in the absence of signals from costimulatory or adhesion molecules. This initial signaling through the TCR rendered the T cells unresponsive (anergic) to subsequent activation by peptide-pulsed APCs. Fluorescent labeling demonstrated that anergic T cells were initially viable, but became susceptible to late apoptosis due to insufficient production of cytokines. Dimerization of the TCR with bivalent MHC class II/peptide complexes therefore allows the induction of anergy in human CD4(+) T cells with a defined MHC/peptide specificity.

HLA-DR2 subtypes & immune responses in pulmonary tuberculosis

BACKGROUND & OBJECTIVES

HLA-DR2 has been shown to be associated with the susceptibility to pulmonary tuberculosis and altered antibody and lymphocyte response in pulmonary tuberculosis. In the present study, the influence of DR2 subtypes on antibody titre and lymphocyte response to Mycobacterium tuberculosis culture filtrate antigens (10 micrograms/ml) was studied in 22 patients with active pulmonary TB (ATB), 50 inactive (cured) TB (ITB) patients and 36 healthy control subjects.

METHODS

HLA-DR2 gene was amplified by polymerase chain reaction (PCR) and dot-blotted. Genotyping of DRB1*1501, *1502, *1503, *1601 and *1602 was carried out using sequence specific oligonucleotide probes (SSOPs) and detected by chemiluminescence method. Antibody titre as well as lymphocyte response to M. tuberculosis antigens were measured by enzyme linked immunosorbent assay (ELISA) and lymphocyte transformation test (LTT) respectively.

RESULTS

The allele frequency of DRB1*1501 was significantly increased in pulmonary tuberculosis patients as compared to controls (P < 0.05). No marked difference in the antibody titre and lymphocyte response to M. tuberculosis antigens was observed between the DRB1 *1501, *1502 and *1503 positive or negative controls, ATB and ITB patients. DRB1 *1501 and *1502 positive as well as negative ATB patients showed a higher antibody titre as compared to controls and ITB patients. ITB patients with *1502 showed a higher lymphocyte response as compared to *1502 positive controls (P < 0.001) and ATB patients (P < 0.05). Similarly, an increased lymphocyte response was observed in *1501, and *1503 negative ITB patients compared to *1501 and *1503 negative controls and ATB patients.

INTERPRETATION & CONCLUSION

The present study revealed that DRB1 *1501 may be associated either alone or with other DR2 alleles, with the susceptibility to pulmonary tuberculosis. None of the DR2 alleles influenced the antibody and lymphocyte response to M. tuberculosis culture filtrate antigens. This suggested that HLA-DR2 gene/gene products as a whole may influence the immune response in pulmonary tuberculosis.

Protective and susceptible HLA polymorphisms in IgA nephropathy patients with end-stage renal failure

Idiopathic immunoglobulin A (IgA) nephropathy is characterised by an extreme variability in clinical course, leading to end-stage renal failure in 15-20% of adults. This subgroup of patients with IgA nephropathy is usually included in the waiting lists of organ exchange organisations. The frequency of HLA-A,B,DR antigens of this subset of IgA nephropathy patients was calculated and compared to controls. The antigens HLA-B35 and DR5 were significantly increased in the patients with relative risk values of 1.385 and 1.487, respectively. The antigens HLA-B7, B8, DR2, and DR3 were found in a significantly lower frequency in the patients as compared to the controls. The relative risk (RR) values ranged between 0.695 and 0.727. Consequently, the haplotypes HLA-A1, B8, DR3, HLA-A3, B7, DR2, HLA-A2, B7, DR2 together with HLA-A1, B15, DR4, HLA-A9, B12, DR7, and HLA-A10, B18, DR2 were found to be protective with RR values ranging from 0.309 to 0.587. The only susceptible haplotype observed was HLA-A2-B5, DR5 (RR=2.990).

Polymorphism of human HLA-DRB1 antigens generated by genetic exchange between DR2 (DRB1*15011) and DR6 (DRB1*1405) alleles: a novel DRB1 allele (DRB1*1437) identified in a Paiwan tribe member of Taiwan

We report herein the identification of a new DRB1 allele using sequence-based typing (SBT). This novel allele, HLA-DRB1*1437, was found in an aboriginal individual from the Paiwan tribe in the southern part of Taiwan. This individual was typed by SBT method as having an HLA genotype of HLA-A*02011/0203, HLA-B*15011/3901, HLA-DRB1*11011/1437, HLA-DRB3*0202/0202, and HLA-DPB1*0501/1301. This new allele differs from DRB1*1309 in the 5'-end nucleotide sequence of polymorphic exon 2 at codon 16 (CAT-->CAA; H16Q), codon 37 (AAC-->TTC; R37F), codon 47 (TTC-->TAC; F47Y), and codon 58 (GCC-->GCT; both specify alanine). By sequence comparison, it was found that this new allele has a 5'-end sequence (from amino acid residues 7 to 66) identical to that found in the DRB1*1405 allele and a 3'-end sequence (from amino acid residues 58 to 94) identical to that found in the DRB1*15011 allele. Both DRB1*1405 and DRB1*15011 alleles have been identified among the Paiwan members (Note).

Polymorphism and distribution of HLA-DR2 alleles in Mexican populations

DRB1*15/16 nucleotide polymorphism was analyzed in 68 DR2 positive individuals (18 Mexican Mestizos, 30 Mazatecans and 20 Nahuas), carrying a total of 75 DR2 haplotypes. HLA-DR2 was one of the most frequent specificities detected in Mazatecans and Nahuas with gene frequency (gf) of 0.232 and 0.141, respectively. In these populations DRB1*16 was the most frequent DR2 split (gf = 0.183 in Mazatecans and gf = 0.135 in Nahuas), whereas in Mexican Mestizos the most frequent was DRB1*15 (gf = 0.065). Four DRB1-DQB1 combinations in Mexican Mestizos, two in Mazatecans and one in Nahuas were in linkage disequilibrium. In spite of the restricted polymorphism, there were differences on DRB1*15/16 alleles found in Mexicans. DRB1*1501 a Caucasian allele was predominant in Mexican Mestizos, whereas DRB1*1602 an Amerindian allele was characteristic on Indian populations. An important difference was detected among the Amerindian populations studied since DRB1*1502 was only present in Mazatecans. This data corroborates the restricted polymorphism of DRB1*15/16 and the high frequency of DRB1*16 subtype in autochthonous American populations and suggest that the differences in gene frequencies of DRB1*15/16 alleles could be helpful in distinguishing each of these population.

CTLA4 in multiple sclerosis. Lack of genetic association in a European Caucasian population but evidence of interaction with HLA-DR2 among Shanghai Chinese

In the present study we searched for an association between multiple sclerosis (MS) and the gene encoding the cytotoxic T lymphocyte antigen 4 (CTLA4). Our experimental approach involved amplification of DNA fragments of the promoter and exon 1 of this gene containing single nucleotide polymorphisms followed by treatment of the amplified fragments with restriction enzymes for allele determination. Included in the study were 84 MS patients and 125 healthy control subjects from a population of white Caucasians. We also examined 42 MS patients and 86 healthy control subjects of Shanghai Chinese origin. Significant differences in the distribution of genotypes or haplotypes of the CTLA4 gene were not observed between MS patients and control subjects in either of the two populations (P>0.05). Moreover, we were not able to confirm a previous finding of an association between relapsing-remitting MS and the heterozygous genotype A/G of CTLA4 exon 1. There was no evidence to suggest that interaction between HLA-DR2 and CTLA4 is involved in the development of MS among European Caucasians (P>0.05). Opposed to this, analysis of the Shanghai Chinese suggested presence of such interaction (P=0.02). Our results do not support the assumption that CTLA4 influences susceptibility to MS in European Caucasians. On the other hand, they raise the possibility that the development of MS in other ethnic groups involves interaction between CTLA4 and DR2.

HLA class II genotypes in Mexican Mestizos with familial and nonfamilial multiple sclerosis

Predisposition to MS is associated with the HLA-DR2 antigen in white patients. The authors investigated the genetic factors behind the increasing frequency of MS in the Mexican population. HLA-DR and DQ were analyzed in 17 patients with MS, 15 of their first-degree relatives, and 99 healthy ethnically matched controls. DR2 or DR3 was found in 15 of 17 patients. In controls, both alleles had frequencies less than 0.05. MS in Mexican patients was associated with HLA-DR2 and DR3.

Structural basis for the binding of an immunodominant peptide from myelin basic protein in different registers by two HLA-DR2 proteins

Susceptibility to multiple sclerosis (MS) is associated with certain MHC class II haplotypes, in particular HLA-DR2. Two DR beta chains, DRB1*1501 and DRB5*0101, are co-expressed in the HLA-DR2 haplotype, resulting in the formation of two functional cell surface heterodimers, HLA-DR2a (DRA*0101, DRB5*0101) and HLA-DR2b (DRA*0101, DRB1*1501). Both isotypes can present an immunodominant peptide of myelin basic protein (MBP 84-102) to MBP-specific T cells from MS patients. We have determined the crystal structure of HLA-DR2a complexed with MBP 86-105 to 1.9 A resolution. A comparison of this structure with that of HLA-DR2b complexed with MBP 85-99, reported previously, reveals that the peptide register is shifted by three residues, such that the MBP peptide is bound in strikingly different conformations by the two MHC molecules. This shift in binding register is attributable to a large P1 pocket in DR2a, which accommodates Phe92, in conjunction with a relatively shallow P4 pocket, which is occupied by Ile95. In DR2b, by contrast, the small P1 pocket accommodates Val89, while the deep P4 pocket is filled by Phe92. In both complexes, however, the C-terminal half of the peptide is positioned higher in the binding groove than in other MHC class II/peptide structures. As a result of the register shift, different side-chains of the MBP peptide are displayed for interaction with T cell receptors in the DR2a and DR2b complexes. These results demonstrate that MHC molecules can impose different alignments and conformations on the same bound peptide as a consequence of topological differences in their peptide-binding sites, thereby creating distinct T cell epitopes.

Multiple sclerosis associated amino acids of polymorphic regions relevant for the HLA antigen binding are confined to HLA-DR2

Among the candidate genes for multiple sclerosis (MS), the strongest influence is conferred by human leucocyte antigen (HLA) class II genes, in particular the DR2, DQ6, Dw2 haplotype (DRB1*1501, DQA1*0102, DQB1*0602). Similar to other autoimmune diseases, it is not clear yet how the presence of a specific HLA-DR or -DQ molecule translates into an increased disease susceptibility. Previous observations by us and others imply a HLA-DR2 dependent propensity of antigen-specific T-cell lines to produce increased amounts of TNF-alpha/beta as one mechanism how DR2 could contribute to susceptibility. In this article, we investigated the distribution of polymorphic stretches of the DRB1, DQA1, and DQB1 chains known to be relevant for antigen binding, in 66 unrelated patients with relapsing remitting MS and 210 unrelated controls. We found a significant association with disease for the appearance of proline at position 11, arginine at position 13, and alanine at position 71 of HLA-DRbeta1. Surprisingly, we identified only residues preferentially expressed in the MS group that were related to HLA-DR2. Thus, the contribution of HLA class II to the pathogenesis of MS is not mediated by allele-overlapping antigen binding sites, but is confined to the disease associated HLA allele.

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.

Sex and age at diagnosis are correlated with the HLA-DR2, DQ6 haplotype in multiple sclerosis

The HLA-DR2, DQ6 (i.e., HLA-DRB1*1501, DQA1*0102, DQB1*0602) haplotype contributes to the risk of developing multiple sclerosis (MS) in Caucasoids of Northern European heritage. A correlation between the clinical expression of MS and the presence of HLA-DR2, DQ6 has, however, not convincingly been shown. In this study conventional bivariate analysis and logistic regression analysis were used to study the relationship between HLA-DR2, DQ6 and four disease variables in a cohort of 286 Norwegian MS patients from the Oslo area. Logistic regression analysis showed that HLA-DR2, DQ6 was significantly more frequent among female than male patients (P=0. 0251), and was negatively correlated with age at diagnosis regardless of sex (P=0.0254). No significant correlation was observed between HLA-DR2, DQ6 and type of disease (relapsing-remitting versus primary chronic progressive MS) or presence/absence of oligoclonal bands in the cerebrospinal fluid.

HLA-DR2-associated DRB1 and DRB5 alleles and haplotypes in Koreans

There are considerable racial differences in the distribution of HLA-DR2-associated DRB1 and DRB5 alleles and the characteristics of linkage disequilibrium between these alleles. In this study, the frequencies of DR2-associated DRB1 and DRB5 alleles and related haplotypes were analyzed in 186 DR2-positive individuals out of 800 normal Koreans registered for unrelated bone marrow donors. HLA class I antigen typing was performed by the serological method and DRB1 and DRB5 genotyping by the PCR-single strand conformational polymorphism method. Only 3 alleles were detected for DR2-associated DRB1 and DRB5 genes, respectively: DRB1(*)1501 (gene frequency 8.0%), (*)1502 (3.2%), (*)1602 (0.9%); DRB5(*)0101 (8.0%), (*)0102 (3.2%), and (*)0202 (0.9%). DRB1-DRB5 haplotype analysis showed an exclusive association between these alleles: DRB1*1501-DRB5*0101 (haplotype frequency 8.0%), DRB1(*)1502-DRB5(*)0102 (3.2%), and DRB1(*)1602-DRB5(*)0202 (0.9%). The 5 most common DR2-associated A-B-DRB1 haplotypes occurring at frequencies of > or = 0.5% were A24-B52-DRB1(*)1502 (1.8%), A2-B62-DRB1(*)1501, A2-B54-DRB1(*)1501, A26-B61-DRB1(*)1501, and A24-B51-DRB1(*)1501. The remarkable homogeneity in the haplotypic associations between DR2-associated DRB1 and DRB5 alleles in Koreans would be advantageous for organ transplantation compared with other ethnic groups showing considerable heterogeneity in the distribution of DRB1-DRB5 haplotypes.

Interaction between HLA-DR2 and abnormal brain MRI in optic neuritis and early MS. Optic Neuritis Study Group

The association of the human leukocyte antigen (HLA)-DR2 allele with brain MRI signal abnormalities and with the development of MS was assessed in 178 patients enrolled in the Optic Neuritis Treatment Trial. HLA haplotype DR2 was present in 85 (48%) of the 178 patients. Its presence was associated with increased odds of probable or definite MS at 5 years (odds ratio, 1.92; 95% confidence interval, 1.01 to 3.67; p = 0.04). The association was most apparent among patients with signal abnormalities on baseline brain MRI.

Linkage of human narcolepsy with HLA association to chromosome 4p13-q21

Although narcolepsy is highly associated with human leukocyte antigen (HLA) DQ6/DQB1*0602 and/or DR2/DRB1*1501, most individuals with the HLA haplotype are free of narcolepsy. This indicates that HLA alone makes a relatively small contribution to the development of narcolepsy and that a non-HLA gene(s) can contribute to the genetic predisposition even in narcoleptic cases with HLA association. We conducted a genome-wide linkage search for narcolepsy in eight Japanese families with 21 DR2-positive patients (14 narcoleptic cases with cataplexy and 7 cases with an incomplete form of narcolepsy). A lod score of 3.09 suggested linkage to chromosome 4p13-q21. A lod score of 1.53 was obtained at the HLA-DRB1 locus, though this lod score may be biased since all the affected patients and many of the family members were DR2-positive. No other loci including hypocretin, hypocretin receptor 1, and hypocretin receptor 2 had lod scores greater than 1.0. The present study suggests that chromosome 4p13-q21 contains a second locus for HLA-associated human narcolepsy.

Association of functional mutant homozygotes of the mannose binding protein gene with susceptibility to pulmonary tuberculosis in India

SETTING

Mannose binding protein gene polymorphism in pulmonary tuberculosis in India.

OBJECTIVE

To find out whether non-HLA genes such as mannose binding protein (MBP) genes are associated in the susceptibility to pulmonary tuberculosis.

DESIGN

Genotyping of MBP 52, 54 and 57 wild and mutant alleles was carried out in HLA-DR typed pulmonary tuberculosis patients (n = 202) and control subjects (n = 109). Since HLA-DR2 is associated with pulmonary-TB, the interaction of MBP genes on -DR2 and non-DR2 genes on the susceptibility was also studied.

RESULTS

A significantly increased genotype frequency of MBP functional mutant homozygotes (including 52, 54 and 57) was seen in pulmonary tuberculosis (PTB) patients (10.9%) than in control subjects (1.8%; P = 0.008; odds ratio: 6.5). Analysis of interaction of MBP genes and HLA-DR2 on the susceptibility to PTB revealed that these genes are associated with PTB independent of each other.

CONCLUSION

The present study shows that functional mutants of MBP are associated with PTB. Apart from HLA-DR2 association, association of non-HLA genes in the susceptibility to PTB is evident. This suggests that multigenetic factors (candidate genes) may be involved in the susceptibility/resistance to PTB.

[Correlative study on HLA-DR2 allelic polymorphism and systemic lupus erythematosus in the Han nationality in Hunan province]

Fifty-eight systemic lupus erythematosus (SLE) patients and 59 normal controls of the Han nationality in Hunan province were involved in this study to analyze the correlation between HLA-DR2 group specific amplification in combination with HLA-DRB generic amplification PCR/SSCP technique to detect the sequence variation within exon 2 of HLA-DR2 alleles outside the sequence specific primer matching positions. The results were that HLA-DR2 was strongly correlated with SLE (RR = 2.71, P < 0.01); and HLA-DRB1 * 1501 was the allele correlated with disease (RR = 3.01, Pc < 0.05). In addition, PCR/SSCP showed that there was not any novel sequence variation in exon 2 of HLA-DR2 alleles in the Han nationality in Hunan province.

DR2 antigens are associated with severity of disease in toxic oil syndrome (TOS)

Toxic oil syndrome (TOS) was an epidemic which broke out in Spain in 1981, caused by the ingestion of rapeseed oil denatured with 2% aniline and sold illegally as edible oil. More than 20,000 people were affected and mortality rate was 8.4%. Genetic susceptibility appears to be involved in the pathology of this disease. Several reports have described association between the chronic stage of the disease and DR-DQ antigens (DR3, DR4, DR2 and DQ8). In the present work, we have reassessed the HLA class II antigens in a well-designed case-control study. Triplets of subjects (n=265) composed by chronic patients (n=117), non-affected family members (n=71) and non-related controls (n=77) were studied. Also, HLA class II antigens were analyzed in patients who had died from TOS (n= 34) and in TOS control patients who died from other non-TOS related causes (n=13). Regarding surviving patients no significant association was found between HLA and disease. In contrast, an increase in phenotypic frequency of DR2 antigen, was found in patients who had died from TOS (73.5%) compared with the whole study group: TOS-affected alive patients (25.6%, corrected P<0.001), non-affected family members (28.5%, corrected P<0.001), non-related controls (23.9%, corrected P<0.001) and dead controls (38.4%, P=0.03).

Kinetics of T-cell receptor binding by bivalent HLA-DR. Peptide complexes that activate antigen-specific human T-cells

Monovalent major histocompatibility complex-peptide complexes dissociate within seconds from the T-cell receptor (TCR), indicating that dimerization/multimerization may be important during early stages of T-cell activation. Soluble bivalent HLA-DR2.myelin basic protein (MBP) peptide complexes were expressed by replacing the F(ab) arms of an IgG2a antibody with HLA-DR2.MBP peptide complexes. The binding of bivalent HLA-DR2.peptide complexes to recombinant TCR was examined by surface plasmon resonance. The bivalent nature greatly enhanced TCR binding and slowed dissociation from the TCR, with a t((1)/(2)) of 2.1 to 4.6 min. Soluble bivalent HLA-DR2.MBP peptide complexes activated antigen-specific T-cells in the absence of antigen presenting cells. In contrast, soluble antibodies to the TCR.CD3 complex were ineffective, indicating that they failed to induce an active TCR dimer. TCR/CD3 antibodies induced T-cell proliferation when bound by antigen presenting cells that expressed Fc receptors. In the presence of dendritic cells, bivalent HLA-DR2. MBP peptide complexes induced T-cell activation at >100-fold lower concentrations than TCR/CD3 antibodies and were also superior to peptide or antigen. These results demonstrate that bivalent HLA-DR. peptide complexes represent effective ligands for activation of the TCR. The data support a role for TCR dimerization in early TCR signaling and kinetic proofreading.

HLA linked with leprosy in southern China: HLA-linked resistance alleles to leprosy

According to the World Health Organization recommended multidrug therapy (WHO/MDT), we have carried out this study to investigate the presence of HLA-linked susceptibility or resistance to leprosy in a southern Chinese population. Sixty-nine leprosy patients and 112 healthy controls participated in the study. HLA-DR2 subtypes, HLA-B and MHC Class I chain-related A (MICA) alleles were typed at the DNA level using the polymerase chain reaction-single strand conformation polymorphism method. The frequencies of HLA-DR2-DRB1 alleles did not show any significant differences between the patient and the control groups, suggesting that the disease susceptibility was not associated with the DR2 subtypes in this southern Chinese population. On the other hand, in the multibacillary (MB) patients significantly decreased allele frequencies of HLA-B46 (0.040 in MB patients vs 0.129 in controls) and MICA-A5 (0.200 vs 0.380) were observed compared with the healthy controls. The calculated relative risk (RR) for B46 was 0.28; for MICA-A5, 0.52. In addition, on haplotype analysis the frequency of the HLA-B46/MICA-A5 haplotype was significantly decreased in the MB patients compared to controls (0.060 vs 0.233, RR = 0.22, p < 0.01). These results suggest that an HLA-linked disease-resistant gene to MB leprosy in southern China is in strong linkage disequilibrium with the HLA-B46/MICA-A5 haplotype. In other words, the resistant gene may be located near the HLA-B/MICA region and not in the HLA-DR locus.

A humanized model for multiple sclerosis using HLA-DR2 and a human T-cell receptor

Multiple sclerosis (MS) is a complex chronic neurologic disease with a suspected autoimmune pathogenesis. Although there is evidence that the development of MS is determined by both environmental influences and genes, these factors are largely undefined, except for major histocompatibility (MHC) genes. Linkage analyses and association studies have shown that susceptibility to MS is associated with genes in the human histocompatibility leukocyte antigens (HLA) class II region, but the contribution of these genes to MS disease development less compared with their contribution to disorders such as insulin-dependent diabetes mellitus. Due to the strong linkage disequilibrium in the MHC class II region, it has not been possible to determine which gene(s) is responsible for the genetic predisposition. In transgenic mice, we have expressed three human components involved in T-cell recognition of an MS-relevant autoantigen presented by the HLA-DR2 molecule: DRA*0101/DRB1*1501 (HLA-DR2), an MHC class II candidate MS susceptibility genes found in individuals of European descent; a T-cell receptor (TCR) from an MS-patient-derived T-cell clone specific for the HLA-DR2 bound immunodominant myelin basic protein (MBP) 4102 peptide; and the human CD4 coreceptor. The amino acid sequence of the MBP 84-102 peptide is the same in both human and mouse MBP. Following administration of the MBP peptide, together with adjuvant and pertussis toxin, transgenic mice developed focal CNS inflammation and demyelination that led to clinical manifestations and disease courses resembling those seen in MS. Spontaneous disease was observed in 4% of mice. When DR2 and TCR double-transgenic mice were backcrossed twice to Rag2 (for recombination-activating gene 2)-deficient mice, the incidence of spontaneous disease increased, demonstrating that T cells specific for the HLA-DR2 bound MBP peptide are sufficient and necessary for development of disease. Our study provides evidence that HLA-DR2 can mediate both induced and spontaneous disease resembling MS by presenting an MBP self-peptide to T cells.

Heterophile anti-mouse immunoglobulin antibodies may interfere with cytokine measurements in patients with HLA alleles protective for type 1A diabetes

Wilson and coworkers (Wilson SB, Kent SC, Patton KT, Orban T, Jackson RA, Exley M, Porcelli S, Schatz DA, Atkinson MA, Balk SP, Strominger JL, Hafler DA: Extreme Th1 bias of invariant V alpha24J alpha Q T-cells in type 1 diabetes. Nature 391:177-181, 1998) have recently reported raised serum levels of interleukin-4 (IL-4) in anti-islet autoantibody-positive first-degree relatives of patients with type 1A diabetes who did not progress to diabetes. Protection from diabetes has been noted for several human lymphocyte antigen (HLA) alleles, such as HLA DR2-DQA1*0102-DQB1*0602. We, therefore, wanted to determine whether this cytokine phenotype was associated with HLA genes protective for type 1A diabetes. We used a two-site fluoroimmunoassay with the same monoclonal antibodies as those reported by Wilson et al. Using this assay, we have found evidence for human heterophile antibodies mimicking serum IL-4: all serum IL-4 reactivity was lost if mouse serum or mouse immunoglobulin were added to the assay; serum IL-4 activity was bound and then eluted by protein A/G chromatography; and levels of anti-mouse antibodies correlated with apparent serum IL-4. This pseudo-IL-4 activity was found in a subset of control subjects, patients with type 1A diabetes, and their relatives and was primarily associated with specific HLA alleles protective for type 1A diabetes (e.g., DQB1*0602). After adjustment for HLA, positive levels of heterophile antibodies were not associated with protection from diabetes. The confounding effect of protective HLA alleles associated with heterophile antibodies could explain the previously reported association between raised serum IL-4 and protection from type 1A diabetes. The mechanism by which specific DQ alleles protect from diabetes and are associated with increased heterophile antibodies is currently unknown.