A molecular basis for MHC class II--associated autoimmunity

Expansion of unusual CD4+ T cells in severe rheumatoid arthritis

OBJECTIVE

The repertoire of T cells in patients with rheumatoid arthritis (RA) is characterized by clonal expansion of selected CD4+ T cells, which are autoreactive and lack the expression of the functionally important CD28 molecule. The goal of this study was to determine the contribution of these unusual lymphocytes to the disease process.

METHODS

RA patients (n = 108) and normal controls (n = 53) were examined for the expression of CD4+ CD28- T cells by 2-color fluorescence-activated cell sorter analysis. Clinical data were ascertained by retrospective chart review.

RESULTS

The frequencies of CD4+ CD28- T cells displayed a bimodal distribution, defining carriers and noncarriers in normal subjects and RA patients. In longitudinal studies, the noncarrier and carrier phenotypes were stable over time. Carriers of CD4+ CD28- T cells accumulated in the RA population (64% versus 45%; P = 0.02). The expansion of CD4+ CD28- T cells correlated with extraarticular involvement, but not with disease duration, antirheumatic treatment, or severity of joint destruction. The patient subsets with nodular disease (P = 0.02) and rheumatoid organ disease (P = 0.04) had the highest proportion of CD4+ CD28- T cell carriers. The size of the CD4+ CD28- compartment correlated with extraarticular progression of RA (P = 0.001 in nodular RA, P = 0.003 in rheumatoid organ disease).

CONCLUSION

The bimodality of distribution of CD4+ CD28- T cell frequencies is compatible with genetic control of the generation of these unusual T cells. In RA patients, CD4+ CD28- T cells are not an epiphenomenon of the disease process, but predispose patients to developing inflammatory lesions in extraarticular tissues.

A single residue polymorphism at DR beta 37 affects recognition of peptides by T cells

Single amino acid polymorphism at residue 37 of the HLA-DR beta chain (DR beta 37) between DRB1*0406 and 0403 markedly influences susceptibility to the insulin autoimmune syndrome. We investigated the effects of DR beta 37 polymorphism regarding recognition of nonself peptides by a T-cell clone, YN5-32, specific to a streptococcal peptide (M12p54-68) presented by the DRB1*0406 molecule. YN5-32 responded better to M12p54-68 presented by allogeneic DRB1*0403 with a single Tyr-substitution at DR beta 37-Ser of the DRB1*0406 molecule. One hundred and fifty-four peptides carrying single residue substitutions at each of the core residues 57-65 of M12p54-68, were tested for full agonistic and TCR antagonistic activities. Forty-six peptides showed full agonism, 34 analogues exhibited TCR antagonism, and 45 analogues exhibited neither full agonism nor TCR antagonism, irrespective of the presenting molecules (DRB1*0406 or 0403). On the other hand, 29 analogue peptides substituted at each of residues 57-63 of M12p54-68 were recognized differently by YN5-32, depending on the presenting molecules. These observations indicate that 1) single amino acid polymorphism (Ser-Tyr) at the DR beta 37 residue induced a conformational change distinguished by TCR in some but not all peptides; and 2) these conformational changes were observed even in analogue peptides carrying single residue substitutions at residues far from a putative DR beta 37 contact site. These findings provide further evidence for altered human T-cell responses induced by TCR ligands with minor modifications.

Tandem peptide epitopes facilitate CD4-dependent activation of T cell clones

Peptides that consist of two tandemly repeated epitopes joined by a flexible linker have an increased affinity for class II molecules and are more potent at inducing proliferation of T cell clones than monomeric epitopes. The increase in potency of peptides with two epitopes for individual T cell clones is proportional to the relative CD4 dependence of the clones. We show that epitope dimers activate T cell clones that respond sub-optimally to monomeric epitopes presented by APC from HIV-infected donors. We hypothesize that HIV+ APC normally fail to stimulate the clones because virally encoded gp 120 sequesters CD4 from the activation complex, but epitope dimers overcome this effect because they are better able to recruit CD4. The alpha beta heterodimer of human class II (HLA-DR1) is further ordered as a dimer of heterodimers (superdimer) at least in its crystal form. Since class II molecules have an open-ended antigen binding groove, the superdimer is theoretically permissive of stable binding of two peptide epitopes linked in tandem. Our data support a role for the MHC class II dimer of heterodimers in amplifying the proliferative response of T cells to antigen by dint of the superdimers having a higher affinity for CD4 than the nominal class II alpha beta heterodimers.

Identification of an HLA-DQ6-derived peptide recognized by mouse MHC class I H-2Db-restricted CD8+ T cells in HLA-DQ6 transgenic mice

CD8+ T cells from C57BL/6(B6) mice show cytotoxicity to B cell blasts prepared from syngeneic transgenic mice expressing HLA-DQ6 molecules in a mouse MHC class I H-2Db restricted manner. Although these results suggest that CD8+ T cells recognize peptides derived from DQ6 molecule bound to H-2Db on target cells, no direct evidence so far has been obtained. To clarify this, we synthesized 23 peptides corresponding to DQ6 alpha or beta chain and carrying the motifs of Db-binding peptides, and examined their capacity to induce cytotoxicity in the CD8+ T cell line. We show here that DQA1-2, one of these peptides, induced cytotoxicity of the CD8+ T cells when this peptide was pulsed to H-2Db expressing target cells, as efficiently as HLA-DQ6 expressing target cells did. Thus, our results suggest that DQA1-2 can be naturally processed from DQ6 molecules and recognized by the CD8+ T cells in the context of H-2Db molecules. These results suggest that allogeneic HLA class II molecules are involved in the rejection not only as the ligand for T cell receptor of alloreactive CD4+ T cells but also as self-peptides bound to HLA class I molecules recognized by CD8+ T cells.

Antigenic peptides and autoimmunity

MHC class II alleles play a major role in determining resistance or susceptibility to autoimmune disease. Considerable effort is being expended to establish the role polymorphisms play in influencing the binding of antigens, including autoantigens, in the peptide-binding groove. Single amino acid substitutions in the MHC cleft, for instance at DR beta 71 and DQ beta 57, influence peptide binding. Although candidate autoantigenic peptides have been identified which bind to disease-associated MHC molecules, several critical questions remain to be answered before the role of these peptides in the autoimmune disease process can be established.

Human leukocyte antigen phenotype imposes complex constraints on the antigen-specific cytotoxic T lymphocyte repertoire

The memory response to the immunodominant Epstein-Barr virus (EBV) epitope FLRGRAYGL, which associates with HLA B8, is exceptionally restricted, being dominated by cytotoxic T lymphocytes (CTL) with a single, public T cell receptor (TCR). CTL clones that express this receptor fortuitously cross-react with the alloantigen HLA B44. However, of the two major subtypes of this HLA, B*4402 and B*4403, that differ by a single amino acid, only the former is recognized by these mature CTL clones. Individuals heterozygous for HLA B8 and B*4402 use alternative TCR for the EBV determinant since the dominant TCR is potentially self-reactive. We now demonstrate that this clonotype is also essentially absent from the repertoire of CTL directed against the viral epitope in seven from seven unrelated individuals heterozygous for HLA B8 and B*4403. Thus immune tolerance of these CTL recognizing HLA B*4402 is associated with expression of either B*4402 or B*4403. This suggests that tolerance in the human T cell compartment requires a lower threshold of recognition than for effector function, thus providing a buffer zone minimizing the risk of autoimmunity. These data also illustrate the potential for non-restricting HLA molecules to bias dramatically the T cell repertoire used for specific immune responses. Such influences may be the basis of the "protective" effects of certain HLA alleles in susceptibility to autoimmune disorders.

Clinical and histological assessment of collagen-induced arthritis progression in the diabetes-resistant BB/Wor rat

Collagen-induced arthritis in the diabetes-resistant BB (DR BB)/Wor rat is a severe, aggressive disease initiated by immunization with heterologous native Type II collagen. Onset of clinical symptoms reproducibly occurs in 100% of animals between days 10 and 12 following collagen immunization. Hypertrophy of the synovial lining is the first histological manifestation of the early inflammatory arthritis. A mild inflammatory infiltrate in the synovium rapidly becomes a fibrovascular pannus eroding articular cartilage and subchondral bone. Beginning at the joint margins, an active synovitis is present. Light microscopy and immunohistochemical staining show the infiltrate to be comprised of mononuclear (lymphocytes, macrophages) and polymorphonuclear inflammatory cells. In addition, there is histological evidence for chronic inflammatory nodules and necrotizing vasculitis in connective tissue from diseased joints, both morphologic features associated with rheumatoid arthritis in humans. Subchondral bone erosion appears to be mediated largely by the resorptive action of activated osteoclasts. These histological parameters of disease progression in the DR BB/Wor rat are similar to human rheumatoid arthritis. The extensive degree of similarity in the pathology of DR BB/Wor rat collagen-induced arthritis and human rheumatoid arthritis supports the role of this model as an in vivo disease model for human rheumatoid arthritis.

IL-1 beta transduces different signals than IL-1 alpha leading to class II antigen expression on beta-insulinoma RIN-5AH cells through specific receptors

Like most cytokines, IL-1 transduces its signals for growth, differentiation and diverse cellular functions after binding to specific receptors on the cell surface. Up to now two IL-1 receptors have been reported, type I which induces signal transduction and type II which binds IL-1 but does not transduce signalling. By using the rat insulinoma RIN-5AH cell line that expresses both types of receptor mRNA, and computer-assisted binding analysis, we show that interleukin-1 beta (IL-1 beta) binds to a single class of high affinity receptors with a Kd of 155 pmol/l. The average number of receptors on adherent cell layer is calculated to be 7300 per cell. 125I-IL-1 beta binding can be competed out by unlabelled IL-1 beta. 125I-IL-1 alpha binding can be also obtained and is subject to competition by cold IL-1 alpha. Its saturation curve, however, varies within experiments due to differential receptor up-regulation. These results have also been confirmed by FACS analysis using specific antibodies to type I and II IL-1 receptors, where type I receptor antibody binds strongly to RIN-5AH cells, and type II receptor antibody shows weak staining, also due to inadequate receptor up-regulation. In order to determine whether functional signal transduction occurs via the receptors detected, it is shown that IL-1 beta is able to induce MHC class II antigen expression on the surface of the RIN cells, whereas IL-1 alpha is unable to do so, indicating different signal reception by the cells. IL-1 beta-induced class II upregulation shows moderate signs of p21ras or/and PKC dependency, whereas IL-1 alpha strongly activates both pathways that probably regulate different functions. Finally, both IL-1 alpha and beta induce nitric oxide (NO) production in a time-dependent fashion which appears to be unrelated to the signals and pathways described, but may be involved in the onset of autoimmune type 1 diabetes.

Study of aspartate at residue 9 of HLA-C molecules in Japanese patients with psoriasis vulgaris

The frequency of aspartate at residue 9 (Asp-9) of HLA-C molecules was investigated among 75 Japanese patients with psoriasis vulgaris and 50 healthy controls. We developed a technique of polymerase chain reaction sequence-specific primer (PCR-SSP) amplification of genomic DNA for HLA-C alleles with a codon for Asp-9. The specificity of amplification was confirmed by direct sequencing of the amplified products and amplification from total RNA (RT-PCR). Asp-9 was positive in all individuals with Cw6 and/or Cw7, but negative in the others, indicating that Asp-9 was specific to Cw6 and Cw7 antigens in our subjects. The frequency of Asp-9 was significantly increased in the patient group (48% vs. 20%; P < 0.002). The frequency of alanine at residue 73 (Ala-73), which was positive for Cw4, Cw6, Cw7, and some C blanks, was also increased in our previous study (81% vs. 48%; P < 0.0001). Asp-9 is located on a beta sheet of alpha 1 domain of HLA-C molecule and influences the peptide binding of the C pocket of the groove together with Ala-73. Both Asp-9 and Ala-73 could contribute to the disease susceptibility to psoriasis vulgaris in the immune responses.

Application of murine T-T hybridoma cells to in vitro potency assay of human synthetic peptide vaccines

Recently, it has been shown that the immunization of mice with an 18 amino acid synthetic peptide corresponding to the third hypervariable region of MHC class II beta chain can induce a specific antibody response against MHC class II molecules, and can be utilized in the prevention and treatment of experimental allergic encephalomyelitis (EAE) [Proc. Natl. Acad. Sci. 1994, 91, 8005-8009]. Based on this finding, a chemically-modified synthetic peptide with the amino acid sequence corresponding to residues of beta 57-76 from human HLA-DR4Dw4 (DR4/1 peptide) is being clinically investigated for the treatment of rheumatoid arthritis in human. The present study describes the development of a novel in vitro potency assay for human HLA-DR4/1 peptide using cloned murine T-T hybridoma cells. Several mouse strains were immunized with the DR4/1 peptide and their lymph node T cell proliferation was measured in the presence of syngeneic APCs and the DR4/1 peptide. T cells isolated from the peptide primed-B10. PL mouse strain, which showed the highest recall response in this assay, were fused with BW5147 lymphoma cells to generate DR4/1 peptide-specific T-T hybridoma clones. Cloned hybridoma cells were characterized for peptide specificity and MHC class II restriction, and used to monitor the biological activity of various DR4/1 peptide preparations. The potency of peptide batches were assessed by measuring the IL-2 secretion of cloned T-T hybridoma cells upon TCR engagement in an antigen-specific manner. The quantitative detection of IL-2 was performed by measuring [3H]thymidine incorporation of HT-2 cells or directly by ELISA. These results demonstrate that peptide-specific murine T-T hybridoma clones can be successfully utilized to monitor biological activity of synthetic peptides by measuring T cell-mediated immunological responses. Development of such in vitro potency assay for synthetic peptides may have broad applications for vaccines related to immunological disorders.

Extended repertoire of permissible peptide ligands for HLA-B*2702

Recognition of self peptides bound to the class I major histocompatibility complex molecule HLA-B27 is thought to trigger proliferation of autoreactive T cells and result in autoimmune arthritic diseases. Previous work from other laboratories established that a predominant feature of endogenous peptides eluted from purified B27 is an arginine at position 2. We studied the binding of peptides containing both natural and unnatural amino acids by the subtype HLA-B*2702, with the goal of gaining insight into peptide binding by this B27 subtype that is associated with susceptibility to arthritic disease. A soluble from of B*2702 was depleted of endogenous peptides. We tested the binding of peptides substituted with cysteine, homocysteine, or an alpha-amino-epsilon-mercapto hexanoic acid side chain (Amh) instead of the naturally occurring arginine at position 2, to determine whether the peptide sulfhydryl residue could be covalently linked to cysteine 67 in the B*2702 binding cleft. Although none of the altered peptide sequences bound covalently to B*2702, the affinities of the homocysteine- and Amh-substituted peptides were close to that of the native peptide sequence. Substitutions at position 2 with other side chains, such as glutamine and methionine, also resulted in peptides that bound with only slightly reduced affinity. These results demonstrate that peptide side chains other than arginine at position 2 can be accomodated within the B*2702 peptide binding site with only minor reductions in affinity. This extended repertoire of permissible B27-binding peptides should be taken into account for a consideration of disease-associated peptide sequences.

Heritable factors distinguish two types of alopecia areata

Alopecia areata (AA) has been shown to be associated with the inheritance of HLA class II alleles. HLA-DQ3 appears to be the general susceptibility allele for AA. Patients with long-standing disease patterns, namely, longterm patchy AA and long-term alopecia totalis and alopecia universalis (AT/AU), can be differentiated by their particular HLA associations. Long-standing AT/AU patients have unique and highly significant associations with HLA antigens DR4, DR11, and DQ7. A complex of early onset, disease severity, family incidence, and associations with HLA DR antigens are characteristic of long-standing AT/AU as distinct from long-standing patchy AA.

Endogenous retroviral long terminal repeats of the HLA-DQ region are associated with susceptibility to insulin-dependent diabetes mellitus

HLA-DQ genes are the main inherited factors predisposing to IDDM. This gene region harbors long terminal repeat (DQ LTR) elements of the human endogenous retrovirus HER V-K, which we analyzed for a possible association with disease. We first investigated whether LTR segregate with DQ alleles in families. Members (n = 110) of 29 families with at least one diabetic child, unrelated patients with IDDM (n = 159), and healthy controls (n = 173) were analyzed. Genomic DNA was amplified for DQ LTR3 by a nested primer approach as well as for DQA1 and DQB1 second exons, to assign DQA1 and DQB1 alleles. DQ LTR segregated in 24 families along with DQ alleles. Of the 29 families, 20 index patients were positive for DQ LTR. The DQ LTR was in all patients on the haplotype carrying the DQA1 *0301 and DQB1 *0302 alleles. A majority of patients had DQ LTR (62%) compared with controls (38%) (p < 1.3 x 10(-5)), even after matching for the high-risk alleles DQA1 *0501, DQB1 *0201-DQA1 *0301, and DQB1 *0302 (79% of patients and 48% of controls; p < 0.02). Subtyping for DRB1 *04 alleles in all DQB1 *0302+ individuals showed 56% DRB1 *0401, DQB1 *0302 [LTR' patients vs. 29% controls with the same haplotype (p < 0.002)]. In conclusion, these data demonstrate the segregation of DQ LTR with DQA1, DQB1 alleles on HLA haplotypes. Furthermore their presence on DRB1 *0401-, DQA1 *0301-, and DQB1 *0302-positive haplotypes suggest that they contribute to DQ-related susceptibility for IDDM.

Expression of recombinant HLA-DR2 molecules. Replacement of the hydrophobic transmembrane region by a leucine zipper dimerization motif allows the assembly and secretion of soluble DR alpha beta heterodimers

Major histocompatibility complex (MHC) class II molecules are membrane-anchored heterodimers that present peptides on the surface of antigen presenting cells to T cells. Soluble HLA-DR2 molecules were expressed for structural and functional characterization of the MHC/peptide/T cell receptor recognition unit. The alpha and beta chains of DR2 (encoded by the DRA, DRB1*1501 genes) did not assemble in mammalian or insect cell lines when the transmembrane regions of one or both chains were truncated. The hydrophobic transmembrane regions of DRalpha and DRbeta facilitate assembly of the heterodimer and were therefore replaced by the leucine zipper dimerization motifs from the transcription factors Fos and Jun, which assemble as a soluble, tightly packed coiled coil structure. The DRalpha-Fos and DRbeta-Jun constructs were expressed in a methyltrophic yeast, Pichia pastoris, using the alpha-mating factor secretion signal to direct expression to the secretory pathway. DR alphabeta heterodimers were purified from supernatants using an antibody specific for the DR alphabeta heterodimer. Kinetic and quantitative peptide binding experiments demonstrated that recombinant DR2 molecules were efficiently loaded with an antigenic peptide. Soluble DR2 molecules can be used to define structural aspects of the MHC/peptide/T cell receptor interaction and to study the signals induced by T cell receptor recognition of soluble DR2.peptide complexes.

Susceptibility to murine experimental autoimmune oophoritis is associated with genes outside the major histocompatibility complex (MHC)

PROBLEM

Neonatal thymectomy induces experimental autoimmune oophoritis in certain strains of mice, and this serves as a model for human autoimmune oophoritis. Because strong MHC associations have been noted in human autoimmune conditions, we investigated the role of MHC in determining susceptibility to murine experimental autoimmune oophoritis. Strain A mice are highly susceptible to post-thymectomy autoimmunity, whereas strain B10 mice are relatively resistant. The availability of congenic strains of mice makes it possible to separate the effects of genetic background and specific H-2 haplotype

METHODS

We neonatally thymectomized A and B10 background female mice, and their H-2 congenic counterparts, and then evaluated the resulting ovarian disease at age 6 weeks.

RESULTS

A. By mice, which have the A background and the H-2b haplotype, developed severe disease equivalent to strain A mice. Similarly, B10.A mice, which have the B background and the H-2a haplotype, failed to develop disease. Thus, H-2a haplotype did not convey disease susceptibility.

CONCLUSIONS

Our findings suggest that immune-regulatory regions outside the H-2 locus play an important role in determining susceptibility to murine post-thymectomy autoimmune oophoritis. This is in accord with our previous findings in women that showed no association between MHC and premature ovarian failure. Thus, in this respect this model is similar to human autoimmune ovarian failure. This suggests that the non-MHC genes conveying susceptibility to autoimmune oophoritis in mice might represent similar predisposing genes for premature ovarian failure in women.

Using transgenic mouse models to dissect the pathogenesis of virus-induced autoimmune disorders of the islets of Langerhans and the central nervous system

Viruses have often been associated with autoimmune diseases. One mechanism by which self-destruction can be triggered is molecular mimicry. Many examples of cross-reactive immune responses between pathogens and self-antigens have been described. This review presents two transgenic models of autoimmune disease induced by a virus through activation of anti-self lymphocytes. Viral antigens are expressed as transgenes either in beta-cells of the pancreas or in the oligodendrocytes of the CNS. Infection by a virus encoding the same gene activated autoreactive T cells that cleared the viral infection, and as a consequence of transgene expression resulted in organ-specific autoimmune disease. In both transgenic mouse models, autoreactive lymphocytes that escaped thymic negative selection were present in the periphery. Several factors are described that play a role in the regulation of the self-reactive process precipitated by a viral infection. These include the quantity of activated autoreactive T cells, the affinity of these T cells, the number of memory T cells generated following primary infection, costimulation by accessory molecules, and the types and locations of cytokines produced. In addition, unique barriers exist in target tissues that prevent or suppress autoreactive responses and define to a large extent the outcome of disease. Restimulation of autoreactive memory lymphocytes may be required to bypass these barriers and enhance autoimmune disease. Therapy directed at modifying these factors can reduce and even prevent autoimmune disease after it has been initiated.

Sequence-specific priming and exonuclease-released fluorescence detection of HLA-DQB1 alleles

Molecular typing of HLA DQB1 alleles, employing sequence-specific primers (SSP) for PCR amplification, was used to test a novel method that eliminates the requirement for subsequent gel electrophoresis or additional hybridization steps by directly detecting positive reactions. We have evaluated the performance of this fluorescence-based oligonucleotide probe assay to assign the most common DQB1 alleles on DNA from 14 homozygous cell lines and in a blind study of 50 diabetic patient samples that had been previously typed at the DQB1 locus using SSOP and conventional SSP-based approaches. We used a panel of 14 DQB1 SSP primer pairs, internal control primers, and a combination of 4 fluorescent oligonucleotide probes to detect 14 alleles or groups of alleles and controls. We can reliably detect single-base allelic differences, observe 100% concordance with the results obtained using both of the standard methods, and are able to further subtype several alleles that are not easily distinguished using SSOP (e.g. DQB1 *0401/0402 and DQB1 *0302/ 0303). Sequence-specific priming and exonuclease-released fluorescence (SSPERF) detection is technically simple and can be performed in less than 2 hours, including DNA extraction, PCR amplification, data analysis and allele identification. This method is particularly useful for the analysis of large numbers of samples, for which high throughput is critical and for which gel-based approaches are difficult to perform. This technique may also be useful for small-scale class I and class II molecular typing in clinically oriented laboratories.

Prospects for development of genetic markers for resistance to gastrointestinal parasite infection in sheep

Selection of sheep for resistance to internal parasites represents a viable option for future parasite control. Many phenotypic measures are available for determining the level of infection in individual sheep, although no phenotypic markers are available which allow prediction of an individual's resistance status. Genetic markers are therefore the best way to incorporate parasite resistance into selection programmes. With the recent development of genetic maps, several experiments are underway to search for markers linked to parasite-resistance genes in sheep. It can be predicted confidently that markers associated with resistance will be discovered within 12 months. Markers useful as selection criteria will be available within 5 years, although considerable quantitative genetic analysis needs to be done to find the best way to utilise marker information in selection programmes. In future, methods for differential DNA analysis or mRNA expression will lead to isolation of the genes involved.

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.

Vaccination with peptides from MHC class II beta chain hypervariable region causes allele-specific suppression of EAE

In our earlier studies we showed that successful immunotherapy of EAE in SJL/J mice can be achieved either by the use of antibodies to MHC class II antigens or by vaccination with synthetic peptide analogs of the beta chain of MHC class II molecules. We proposed that inhibition of EAE following vaccination with synthetic peptides derived from the beta chain of mouse I-A, was in part due to the generation of auto-anti-MHC class II antibodies that interfered with T cell sensitization. In our present study we show that suppression of EAE following vaccination results in poor sensitization of MBP reactive T cells, and that the lack of immune response is allele-specific. In F1(SJL(I-AS) x Balb/cI-Ad) mice, in which susceptibility to EAE is linked closely to the I-AS allele, vaccination with peptides from beta chain of I-AS results in inhibition of proliferative response to MBP and prevents the development of EAE. Vaccination with peptide from the beta chain of I-Ad did not affect either the development of immune response to MBP or the induction of EAE, indicating allele-specific suppression. Since global immunosuppression is not induced by vaccination with I-A peptides, we propose that this strategy can be extended to human autoimmune diseases wherein a clear association between certain MHC class II alleles and autoimmune disease is evident.

Specificity of an HLA-DRB1*0401-restricted T cell response to type II collagen

A panel of HLA-DRB1*0401-restricted CD4+ mouse T cell hybridomas specific for bovine type II collagen were generated from transgenic mice expressing the human HLA-DRA1*0101/-DRB1*0401 and CD4 molecules. The vast majority recognized a single peptide determinant corresponding to residues 261-273 (CII 261-273). This determinant was rapidly defined by the use of a predictive algorithm for peptide binding to DRB1*0401. CII 261-273 is conserved in bovine and human type II collagen and overlaps with an important I-A q - restricted T cell determinant in mice with collagen-induced arthritis. This study demonstrates how HLA-DR and human CD4-transgenic mice can be used to identify a T cell epitope in a potential or candidate autoantigen.

High frequencies of identical T cell clonotypes in synovial tissues of rheumatoid arthritis patients suggest the occurrence of common antigen-driven immune responses

OBJECTIVE

To investigate T cell antigen receptor (TCR) clonotypes in rheumatoid arthritis (RA) lesions.

METHODS

Reverse transcriptase-polymerase chain reaction with TCR V beta family-specific primers and subsequent single-strand conformation polymorphism (SSCP) analysis were performed. Direct nucleotide sequencing was also conducted.

RESULTS

A distinct clonal expansion of T cells was observed in the synovium. Furthermore, identical bands in samples of different areas of the same lesion were obtained by SSCP analysis. Nucleotide sequencing revealed that T cell clonotypes of identical mobility on SSCP analysis had the same nucleotide sequence and thus were identical clones. In 6 RA patients, 60-100% of the expanded T cell clonotypes had identical migration patterns in 2 different samples, indicating that this percentage represents commonly existing T cell clonotypes in the affected joint. Furthermore, the J beta 2.1 gene segment was used predominantly by the TCR V beta clonotypes that commonly expanded in the different portions of the same joint.

CONCLUSION

These results suggest that the immune response in RA is not random, but rather is driven by common stimuli.

Different contribution of HLA-DR and -DQ genes in susceptibility and resistance to insulin-dependent diabetes mellitus (IDDM)

Previous studies have indicated that certain alleles of HLA-DR and -DQ genes were strongly associated with susceptibility and resistance to insulin-dependent diabetes mellitus (IDDM), and the role of DQ molecule in IDDM has been suggested. To further clarify the association of DQ alleles with IDDM, we determined the nucleotide sequences of full-length cDNA from 13 DQA1 alleles and 14 DQB1 alleles. The sequencing analysis revealed sequence polymorphisms outside the hypervariable region of DQ genes. We then analyzed the DQA1 and DQB1 polymorphisms along with that of DRB genes in 86 B-lymphoblastoid cell lines (B-LCLs) from various ethnic groups and in healthy unrelated Japanese and Norwegian individuals. The allelic and haplotypic distributions in each population revealed the characteristic haplotypic formation in the HLA class II region. HLA genes in 139 Japanese and 100 Norwegian IDDM patients were analyzed. DQB1*0301 was negatively associated with IDDM in both ethnic groups, irrespective of associated DRB1 and DQA1 alleles. In DQB1*0302 positive populations, which represented a positive association with IDDM in both ethnic groups, DRB1*0401, *0404, *0802 haplotypes increased in the patients, whereas DRB1*0406 haplotype decreased. Considering about the hierarchy in DRB1 alleles with IDDM susceptibility (DRB1*0401>*0404>*0403 in Norwegian and DRB1*0802>*0403>*0406 in Japanese), the genetic predisposition to IDDM is suggested to be defined by the combination of DR-associated susceptibility and DQ-associated susceptibility and by the DQ-associated resistance which is a dominant genetic trait.

Structural basis for major histocompatibility complex (MHC)-linked susceptibility to autoimmunity: charged residues of a single MHC binding pocket confer selective presentation of self-peptides in pemphigus vulgaris

Human T-cell-mediated autoimmune diseases are genetically linked to particular alleles of MHC class II genes. Susceptibility to pemphigus vulgaris (PV), an autoimmune disease of the skin, is linked to a rare subtype of HLA-DR4 (DRB1*0402, 1 of 22 known DR4 subtypes). The PV-linked DR4 subtype differs from a rheumatoid arthritis-associated DR4 subtype (DRB1*0404) only at three residues (DR beta 67, 70, and 71). The disease is caused by autoantibodies against desmoglein 3 (DG), and T cells are thought to trigger the autoantibody production against this keratinocyte adhesion molecule. Based on the DRB1*0402 binding motif, seven candidate peptides of the DG autoantigen were identified. T cells from four PV patients with active disease responded to one of these DG peptides (residues 190-204); two patients also responded to DG-(206-220). T-cell clones specific for DG-(190-204) secreted high levels of interleukins 4 and 10, indicating that they may be important in triggering the production of DG-specific autoantibodies. The DG-(190-204) peptide was presented by the disease-linked DRB1*0402 molecule but not by other DR4 subtypes. Site-directed mutagenesis of DRB1*0402 demonstrated that selective presentation of DG-(190-204), which carries a positive charge at the P4 position, was due to the negatively charged residues of the P4 pocket (DR beta 70 and 71). DR beta 71 has a negative charge in DRB1*0402 but a positive charge in other DR4 subtypes, including the DR4 subtypes linked to rheumatoid arthritis. The charge of the P4 pocket in the DR4 peptide binding site therefore appears to be a critical determinant of MHC-linked susceptibility to PV and rheumatoid arthritis.

Both MHC and background gene heterozygosity alter T cell receptor repertoire selection in an antigen-specific response

Many autoimmune diseases are associated with specific class II MHC alleles; however, this association is not complete. One explanation for the variable expression of disease in susceptible individuals is that variability in the TCR repertoire may alter the potential to generate pathogenic autoreactive T cells. The current study was undertaken to examine the possibility that MHC and background heterozygosity, which is the norm in the outbred human population, alters the expressed TCR repertoire and, if so, whether this has an impact on peptide recognition and antigenic specificity. We, therefore, systematically analysed the beef insulin-specific TCR repertoire in inbred BALB/c mice before and after introduction of MHC heterozygosity (BALB/c x BALB.K)F1 mice, or MHC and background gene heterozygosity (BALB/c x A/J)F1 mice. We show that T cells from all three repertoires are predominantly Ad-restricted and recognize the same immunodominant peptide. Despite this, the beef insulin-specific TCR repertoires in F1 mice differ from those seen in BALB/c mice with the most dramatic changes seen in (BALB/c x A/J)F1 mice. These changes are accompanied by subtle differences in the antigenic specificity of the T cells. The results demonstrate that both MHC and background gene heterozygosity affect TCR repertoire selection, suggesting that the variable expression of autoimmune disease in individuals with a susceptible MHC allele may result, in part, from variability in the TCR repertoire introduced by this heterozygosity.

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.

The presence of the HLA class II allele DPB1*0501 in ethnic Thais correlates with an enhanced vaccine-induced antibody response to a malaria sporozoite antigen

In this study, we examined the correlation between the frequency of allelic variants of the class II human leukocyte antigen (HLA) DR, DQ and DP gene loci and the quantitative humoral immune response observed in 71 Thai volunteers, subsequent to vaccination with a conjugated subunit vaccine. This vaccine was designed to induce antibodies directed against the immunodominant repeat region of the Plasmodium falciparum circumsporozoite (CS) protein. The presence of the DPB1*0501, a relatively common allele in Asian populations, was found to be associated with high vaccine-induced CS repeat-specific antibody responses in the volunteers. Given the increasing focus on the use of subunit vaccines in the control of infectious diseases, consideration of the influence of class II allele frequencies in ethnically diverse recipient populations may be important.

Transfer of rheumatoid arthritis into severe combined immunodeficient mice. The pathogenetic implications of T cell populations oligoclonally expanding in the rheumatoid joints

To investigate the pathogenicity of T cells infiltrating in the rheumatoid joints, mononuclear cells (MNC), predominantly T cells, isolated from either synovial fluid or synovial tissues of the patients with RA were transferred into severe combined immunodeficient (SCID) mice by intraarticular injections. According to our observations in this experimental system, patients with RA could be classified into at least two groups. In one group of patients, the infiltrating MNC induced synovial hyperplasia in the recipient SCID mice (the positive group). Whereas, in the other group no synovial hyperplasia was observed (the negative group). The induction of synovial hyperplasia observed in the positive group was prevented by an anti-human CD3 antibody (OKT3), indicating T cell mediation. Analysis of T cell receptor (TCR) V beta usage by reverse transcriptase polymerase chain reaction in the infiltrating MNC transferred into SCID mice revealed a marked skew towards the preferential use of certain V beta genes, which was not seen in the peripheral blood MNC, in only the positive group. The patterns of TCR/V beta skew were not uniform among the patients. The analysis of the PCR-amplified genes of such skewed TCR/ V beta by single strand conformational polymorphism showed distinct bands, indicating that the T cell populations expanding in rheumatoid joints of the positive group were oligoclonal. Furthermore, the enrichment of the T cell populations expressing such skewed TCR/V beta by in vitro stimulation of peripheral blood MNC of the patients with the relevant superantigen enabled the induction of synovial hyperplasia in the SCID mice. These results suggest that the pathogenic T cells could be activated locally in rheumatoid joints by certain antigens in some, but not in all patients with RA.

Aetiopathogenesis of Takayasu's arteritis and BCG vaccination: the missing link?

Takayasu's arteritis is an inflammatory disease of unknown aetiology involving the aorta, its major branches and pulmonary arteries. Historical, epidemiological and immunological data are presented which suggest that BCG vaccination in the susceptible host might be important in the pathogenesis of Takayasu's arteritis. This hypothesis best explains the various known facts about the disease.

Emergence of oligoclonal T cell populations following therapeutic T cell depletion in rheumatoid arthritis

OBJECTIVE

To examine the compartment of CD4+ T cells in patients with rheumatoid arthritis (RA) who have developed persistent lymphopenia following antibody-mediated T cell depletion and to investigate why T cell depletion is of limited therapeutic efficacy.

METHODS

Circulating T lymphocytes from 10 patients with seropositive RA treated with the monoclonal antibody (MAb) CAMPATH-1H were longitudinally monitored by fluorescence-activated cell sorter analysis with MAb. To assess the molecular diversity of repopulating T cells, random samples of T cell clones from the peripheral blood of 3 patients were analyzed by sequencing the T cell receptor (TCR) beta chains. At the time of recurring disease, the synovial tissue was examined by immunohistochemistry, and the repertoires of peripheral and synovial tissue T cells were compared by TCR beta-chain sequencing and by semiquantitative hybridization with oligonucleotides specific for the V-D-J beta junctional region of selected clones.

RESULTS

The reconstitution of the peripheral T cell compartment was very slow. A mean CD4+ T cell count of 105/microliters was reached 34 weeks following MAb treatment. After treatment, the percentage of CD4+ T cells with the CD45RO+ phenotype was significantly increased (P = 0.001), indicating the expansion of antigen-primed memory T cells. TCR beta-chain sequences revealed a marked restriction in the diversity of repopulating T cells with the emergence of dominant clonotypes. Despite the low counts of peripheral CD4+ T cells, the synovial tissue was infiltrated by CD4+ T cells to a similar extent as that in RA patients not treated with MAb. Selected clonotypes that had emerged in the peripheral blood compartment dominated the repertoire of tissue-infiltrating T cells in the synovium.

CONCLUSION

In patients with RA, T cell depletion induces a long-term imbalance in T cell homeostasis. Clonal proliferation of CD4+ T cells severely restricts the diversity of available T cell specificities and results in the emergence of dominant clonotypes, which accumulate in the synovial tissue despite peripheral lymphopenia.

Autoantibodies before, during and after administration of recombinant interferon-alpha for chronic viral hepatitis

This study was undertaken to investigate the presence of autoantibodies in patients with chronic viral hepatitis B and C, before, during and after interferon-alpha (IFN-alpha) therapy and to study their relation to dose and type of IFN-alpha and response to treatment. Fifty patients with chronic hepatitis were divided in two groups, a control-group of 21 patients (10 type B and 11 type C) who were followed for 6 months without treatment and an IFN-group consisting of 29 patients (8 type B and 21 type C) who received IFN therapy for 6 months. Serum samples were tested for a range of antibodies at the start of the study, during therapy and at the end of the 6 month period. Antibodies tested for included: antinuclear, smooth muscle, antimitochondrial, parietal cell and thyroid microsomal. Four (8%) of the total patient group had autoantibodies at the beginning of the study (two in each group). During the follow-up period no patient in the control group developed antibodies compared with 3 (11%) patients in the treatment group. Autoantibodies developed in patients treated with higher doses of IFN and were found in those patients who tended to show a poor response to IFN-therapy. Further studies are needed to establish the relationship between poor response to IFN-alpha and development of autoantibodies.

Genetic background and environment contribute synergistically to the onset of autoimmune diseases

Autoimmune diseases result from the breakdown of "self" tolerance. Environmental factors appear to be responsible for triggering this errant immune response, directed against self-tissue determinants, only when a susceptible genetic background is present in an individual. Autoimmune diseases, normally characterized by their association with certain HLA alleles, also share other features: the presence of autoantibodies, autoreactive T lymphocytes, and an intermittent clinical course of exacerbations and remissions. In cases of organ-specific diseases, as well as in cases of multi-system autoimmune diseases, viruses are increasingly implicated as such environmental triggers. Current molecular biology techniques have permitted a fine dissection of the genetic background of susceptible individuals and have enabled a more complete characterization of the immunocompetent cells involved in this autoaggression. Molecular approaches will soon allow us to pinpoint the characteristics of the environmental stimuli, so that protective strategies could be formulated to spare susceptible individuals from their ill effects.

HLA DQA1-DQB1-TAP2 haplotypes in IDDM families: no evidence for an additional contribution to disease risk by the TAP2 locus

The TAP2 gene, located in the HLA class II region, encodes a subunit of a transporter involved in the endogenous antigen-processing pathway, and has been suggested to contribute to the genetic risk for insulin-dependent diabetes (IDDM). In order to determine whether the TAP2 locus modulates the risk conferred by HLA DQ loci, HLA DQA1-DQB1-TAP2 haplotypes were analysed in 48 IDDM probands, their first degree relatives, and in 62 normal control subjects. A decreased frequency of the TAP2B allele was confirmed in this IDDM cohort (12 vs 28% in control subjects, pc < 0.05). Analysis of 73 informative meiotic events in IDDM and control families demonstrated a recombination fraction between HLA DQB1 and TAP2 loci of 0.041 (Log of the odds score = 16.5; p < 10(-8)) indicating strong linkage between these loci. Family haplotype analysis demonstrated linkage disequilibrium between TAP2 and HLA DQA1-DQB1, and showed that the reduced frequency of TAP2B was associated with its absence on the IDDM susceptible DQA1*0301-DQB1*0302 haplotype, its low frequency on DQA1*0501-DQB1*0201, and the association of TAP2B with DQA1*0101-DQB1*0501 haplotypes which were less frequent in IDDM patients. Comparison of transmitted with non-transmitted haplotypes in IDDM families showed a slight but not significant decrease in TAP2B allele frequency on transmitted (3 of 37) vs non-transmitted (2 of 9) HLA DQA1*0501-DQB1*0201 haplotypes. No other differences were observed. Twenty-four unrelated DQA1*0501-DQB1*0201 haplotypes from non-diabetic families had a TAP2B allele frequency (4%) similar to that in IDDM haplotypes.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular genetics of diabetes mellitus

As a result of advances in technology, genome searches have been carried out for susceptibility genes for type 1 diabetes in humans and in the NOD mouse. These have shown that, in the NOD mouse, diabetes susceptibility is under the control of at least ten separate chromosomal loci. In the human, in addition to HLA and INS, two new susceptibility genes have been localized, IDDM4 on chromosome 11q and IDDM5 on 6q, demonstrating the polygenic nature of type 1 diabetes and the role of HLA as the major locus. Candidate genes at these loci are the subject of current investigation. Genetic and immunological markers of disease may be of value in screening the general population for individuals at risk of developing type 1 diabetes. The predictive power of different screening strategies should be tested in order to work out the potential value to the general population of preventive therapies that are now undergoing clinical trials in high risk 'pre-diabetics'. Type 2 diabetes is genetically heterogeneous, and, since 1992, two distinct genetic subtypes have been identified. The first is defined by mutations in the GCK gene, which cause up to 60% of cases of MODY. The second, designated MIDD (maternally inherited diabetes and deafness), is defined by mutation in the mitochondrial gene for tRNA(Leu(UUR)). MIDD patients are less obese than is usual for typical type 2 diabetes, may present in early adult life or occasionally in childhood and may have been diagnosed as having autoimmune type 1 diabetes, type 2 diabetes or MODY. Typically, patients with MIDD require insulin earlier than do type 2 diabetics without mitochondrial mutations. Genetically complex diseases, such as diabetes, hypertension, cancer and coronary heart disease, are common in most populations. The approaches to the genetic analysis of diabetes outlined in this review are likely to be useful to the genetic analysis of many of these disorders. Progress in this area will have important implications for public health strategies in the next decade and beyond.

Mechanisms underlying the formation of the T cell receptor repertoire in rheumatoid arthritis

The contributions of germline-encoded T cell receptor segments and of HLA-DR polymorphisms in shaping the repertoire of human CD4+ CD45RO- T cells were investigated in healthy unrelated individuals and in patients with rheumatoid arthritis, an HLA-DRB1 04-associated disease. By comparing frequencies of V beta-J beta combinations, healthy individuals segregated into independent clusters, which strongly correlated with the HLA-DRB1 allele expression. The repertoire fingerprint imposed by the HLA-DRB1 alleles involved only a selected group of J beta elements, whereas the distribution of the other J beta segments was HLA independent. The HLA-restricted J beta elements are characterized by a Gly-Pro-Gly sequence within the conserved Phe-Gly-X-Gly motif, which induces rigidity in an otherwise more flexible protein backbone. The T cell receptor repertoire distinguished patients with RA from healthy HLA-DR-matched individuals, suggesting that patients share a selection mechanism that significantly distorts the composition of the T cell receptor repertoire.

T-cell receptor V alpha and V beta gene use by infiltrating T cells in labial glands of patients with Sjögren's syndrome

Sjögren's syndrome is an autoimmune disease affecting the exocrine glands; it is thought to result from T-cell-mediated damage. In the labial glands of 20 patients with Sjögren's syndrome, infiltrating T cells were immunohistochemically characterized, and T-cell receptor (TCR) gene expression was examined with a method based on polymerase chain reaction. Most of these lymphocytes expressed CD3, CD4, CD45RO, and TCR alpha beta, whereas less than 5% of them expressed CD25 and CD69. The TCR V alpha and V beta genes expressed in peripheral blood mononuclear cells were diverse, whereas the TCR V alpha and V beta repertoires in the labial glands were more restricted but were still heterogeneous. The predominantly used V alpha and V beta families in the labial glands, when compared with those in peripheral blood mononuclear cells, were found to vary in individual patients and also to differ from patient to patient. Thus the T-cell population in the labial glands was polyclonal but showed a more restricted pattern than that seen in peripheral blood mononuclear cells.

PVU II polymorphism of LST-1 (leucocyte specific transcript-1) in type I diabetes mellitus, Graves' disease and healthy controls

The polymorphism of the LST-1 gene (the human homologue of the mouse B144 gene) can be identified by Pvu II restriction enzyme digestion. We investigated the contribution of this RFLP to disease susceptibility in 117 patients with type I diabetes mellitus (IDDM), 110 with Graves' disease (GD) and 93 healthy controls. The distribution of the different LST-1 alleles (LST-1*1:1323 bp, LST-1*2:610 bp/713) was similar among IDDM and GD patients as well as in controls. The combination of DQA1*0501, DQB1*0201 and DQB1*0301, all predisposing to endocrine autoimmune disease, with LST-1*1 or LST-1*2 was not increased in patients. Analysis of two informative families with IDDM demonstrated cosegregation of DQA1 and DQB1 alleles with LST-1 alleles. No association of LST-1 polymorphisms with IDDM nor GD could be demonstrated.

HLA-DQB1 allele associates with idiopathic nephrotic syndrome in Japanese children

HLA-DQA1 and -DQB1 genes were investigated in 30 Japanese children with idiopathic nephrotic syndrome (INS) using the polymerase chain reaction-restriction fragment length polymorphism method. Compared with control children, there was a significant increase in the HLA-DQA1*0501, DQB1*0301 and DQB1*0601 alleles, whereas the frequency of DQB1*0501 showed a significant decrease in the patients. The increase of DQA1*0501 can be explained as being a result of a linkage disequilibrium with DQB1*0301. The previous result demonstrating a positive association of DRw6 and DRw8 with INS is also assumed to be attributable to a linkage disequilibrium with DQB1*0301 and 0601. A total of 83% of patients compared with 37% of controls possessed DQB1*0301 and/or DQB1*0601 allele (P < 0.001, RR = 8.6). Only these alleles have alanine at residue 13 and tyrosine at residue 26 in the hypervariable region in the Beta 1 domain of DQB1 gene. These findings suggest that the unique amino acid residues in the DQB1 gene may contribute to disease susceptibility in Japanese children with INS.

Correlation between disease phenotype and genetic heterogeneity in rheumatoid arthritis

RA is a heterogeneous group of disorders characterized by variations in clinical manifestations, disease course, and probably response to therapeutic interventions. We have addressed the question whether genetically and potentially etiologically more homogeneous subgroups of RA patients can be defined based upon the expression of the RA-linked sequence motif in the third hypervariable region of the HLA-DRB1 gene. Genetic comparison of patients classified upon clinical manifestation and disease course demonstrated that patients with mild disease were genetically distinct from those progressing to severe and destructive disease. Specifically, rheumatoid factor (RF) negative patients preferentially expressed RA-linked HLA-DRB1 alleles with an arginine substitution in position 71, whereas the alleles with a lysine substitution in position 71 accumulated in RF+ patients. RF- patients were further subdivided based on clinical markers (time of onset of erosive disease and requirement for aggressive therapy). Clinical heterogeneity correlated with genetic heterogeneity. Patients with early erosive disease and patients requiring aggressive therapy frequently typed HLA-DRB1*04+. Patients with late erosive/nonerosive disease or a benign disease course manageable with nonaggressive treatment preferentially expressed HLA-DRB1*01 or lacked an RA-linked haplotype. These data indicate that the heterogeneity of RA reflects genetic differences. Sequence variations within the disease-linked sequence motif, as well as polymorphisms surrounding the candidate genetic element, affect pattern, course, and treatment response of RA. Amino acid position 71 in the HLA-DRB1 gene has a unique role, the understanding of which may provide important clues to disease etiology.

Clinical features of sarcoidosis in relation to HLA distribution and HLA-DRB3 genotyping by PCR-RFLP

BACKGROUND

Susceptibility to the development of sarcoidosis has been demonstrated to be associated with HLA-DR5, -DR6, and -DR8 encoded by the DRB1 gene. However, involvement of the DRB3 (HLA-DR52) gene in the development of sarcoidosis remains unclear.

METHODS

HLA-DRB3 genotyping was performed using the PCR-RFLP method and the clinical features of the patients with and without the DR3, 5, 6, 8 group antigens were compared.

RESULTS

HLA-DRB3 genotyping indicated an association between DRB3*0101 and sarcoidosis. The DR8 haplotype lacking the DRB3 gene has been found to be increased significantly in sarcoidosis, suggesting that the HLA-DRB3 gene is not a primary determinant of predisposition to sarcoidosis. The association of DRB3*0101 with sarcoidosis is attributable to linkage disequilibrium with DR5- and DR6-associated alleles. There were significant decreases in the DR3, 5, 6, 8 group (DR5, DR6, or DR8) antigen frequencies in patients with retinal perivasculitis, high intraocular pressure (or secondary glaucoma), and optic nerve and/or macular lesion. Correlations were observed among the DR3, 5, 6, 8 group antigens, early onset sarcoidosis and disease with fewer intraocular lesions.

CONCLUSION

This established a molecular basis for some of the clinical heterogeneity observed in sarcoidosis.