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Major histocompatibility (MHC) class II molecules are strongly associated with many autoimmune disorders. In type 1 diabetes (T1D), the DQ8 molecule is common, confers significant disease risk, and is involved in disease pathogenesis. We hypothesized that blocking DQ8 antigen presentation would provide therapeutic benefit by preventing recognition of self-peptides by pathogenic T cells. We used the crystal structure of DQ8 to select drug-like small molecules predicted to bind structural pockets in the MHC antigen–binding cleft. A limited number of the predicted compounds inhibited DQ8 antigen presentation in vitro, with 1 compound preventing insulin autoantibody production and delaying diabetes onset in an animal model of spontaneous autoimmune diabetes. An existing drug with a similar structure, methyldopa, specifically blocked DQ8 in patients with recent-onset T1D and reduced inflammatory T cell responses to insulin, highlighting the relevance of blocking disease-specific MHC class II antigen presentation to treat autoimmunity.

UTokyo Research掲載「免疫タンパク質の不安定さが、自己免疫疾患のかかりやすさに関係」 URI: http://www.u-tokyo.ac.jp/ja/utokyo-research/research-news/autoimmunity-associated-genes-encode-exceptionally-unstable-proteins/, UTokyo Research "Autoimmunity associated genes encode exceptionally unstable proteins" URI: http://www.u-tokyo.ac.jp/en/utokyo-research/research-news/autoimmunity-associated-genes-encode-exceptionally-unstable-proteins/

Selection of biased T cell receptor (TCR) repertoires across individuals is seen in both infectious diseases and autoimmunity, but the underlying molecular basis leading to these shared repertoires remains unclear. Celiac disease (CD) occurs primarily in HLA-DQ2.5+ individuals and is characterized by a CD4+ T cell response against gluten epitopes dominated by DQ2.5-glia-α1a and DQ2.5-glia-α2. The DQ2.5-glia-α2 response recruits a highly biased TCR repertoire composed of TRAV26-1 paired with TRBV7-2 harboring a semipublic CDR3β loop. We aimed to unravel the molecular basis for this signature. By variable gene segment exchange, directed mutagenesis, and cellular T cell activation studies, we found that TRBV7-3 can substitute for TRBV7-2, as both can contain the canonical CDR3β loop. Furthermore, we identified a pivotal germline-encoded MHC recognition motif centered on framework residue Y40 in TRAV26-1 engaging both DQB1*02 and the canonical CDR3β. This allowed prediction of expanded DQ2.5-glia-α2–reactive TCR repertoires, which were confirmed by single-cell sorting and TCR sequencing from CD patient samples. Our data refine our understanding of how HLA-dependent biased TCR repertoires are selected in the periphery due to germline-encoded residues. This research was originally published in JCI Insight. © 2018 American Society for Clinical Investigation

Celiac disease is associated with HLA-DQ2 and, to a lesser extent, HLA-DQ8. Type 1 diabetes is associated with the same DQ molecules in the opposite order and with possible involvement of trans-encoded DQ heterodimers. T cells that are reactive with gluten peptides deamidated by transglutaminase 2 and invariably restricted by DQ2 or DQ8 can be isolated from celiac lesions. We used intestinal T cells from celiac patients to map DQ2 and DQ8 epitopes within 2 representative gluten proteins, alpha-gliadin AJ133612 and gamma-gliadin M36999. For alpha-gliadin, DQ2- and DQ8-restricted T cells recognized deamidated peptides of 2 separate regions. For gamma-gliadin, DQ2- and DQ8-restricted T cells recognized deamidated peptides of the same region. Some gamma-gliadin peptides were recognized by T cells in the context of DQ2 or DQ8 when bound in exactly the same registers, but with different requirements for deamidation; deamidation at peptide position 4 (P4) was important for DQ2-restricted T cells, whereas deamidation at P1 and/or P9 was important for DQ8-restricted T cells. Peptides combining the DQ2 and DQ8 signatures could be presented by DQ2, DQ8, and trans-encoded DQ heterodimers. Our findings shed light on the basis for the HLA associations in celiac disease and type 1 diabetes.

In this study, a large number of naturally processed peptides was isolated and identified from the human diabetes-susceptible class II MHC molecules HLA-DQ8 (DQA1*0301,DQB1*0302) and from murine I-Ag7 species, both of which are expressed in genetically identical APC lines. The peptides presented during the processing of autologous proteins were highly selective in showing sequence specificity, mainly consisting of 1 or more acidic residues at their C terminus. Testing for binding to the MHC molecules revealed that the position 9 (P9) acidic residues of the peptides contributed decisively to binding. For HLA-DQ8, the P1 residue, which was also an acidic amino acid, influenced binding positively. Both HLA-DQ8 and I-Ag7 selected for common peptides that bound in the same register. There was no evidence for selection of peptides having nonspecific or promiscuous binding. Thus, diabetogenic class II MHC molecules are highly selective in terms of the peptides presented by their APCs, and this is governed by the features of their P9 anchor pocket. These results are in striking contrast to those from studies examining synthetic peptide or phage display libraries, in which many peptides were shown to bind.

Dermatitis herpetiformis (DH) is an autoimmune blistering skin disorder that is associated with gluten sensitivity. It presents as a papulovesicular rash and is often associated with enteropathy. The rash resolves when the patient is placed on a gluten-free diet and/or dapsone. DH, as well as celiac disease, is tightly associated with DQ2 and DQ8. A novel mouse model for DH is described that utilizes the NOD background and the HLA-DQ8 transgene. The addition of DQ8 contributes sensitivity to gliadin, and the addition of the NOD background contributes to autoimmunity and pathogenesis. Fifteen NOD DQ8+ mice of 90 that were sensitized to gluten developed blistering pathology similar to that seen in DH. Neutrophil infiltration of the dermis, deposition of IgA at the dermal-epidermal junction, and a complete reversal of the blistering phenomenon with the administration of a gluten-free diet with or without dapsone were observed. None of the 3 blistering mice examined had small-bowel pathology. This animal model of DH will be useful to determine the specificity of the IgA deposits, as well as the pathogenic mechanisms that occur in the skin as a result of gluten ingestion.

Relapsing polychondritis is a multisystem autoimmune disease involving cartilage destruction but no known causative antigen. HLA-DQ8 has been associated with various autoimmune diseases in humans. To study the role of DQ8in autoimmune diseases, we have generated transgenic mice expressing DQ8 (DQA1*0301, DQB1*0302) in a NOD background lacking endogenous class II molecules (Aβo). Upon immunization with type II collagen (CII), 85% of NOD.DQ8 mice develop severe experimental polychondritis, auricular chondritis, and polyarthritis, with clinical and histological similarities to relapsing polychondritis (RP) in humans. CII-immunized mice mount a T cell response and produce Ab's to type IX collagen (CIX) and self-CII. Transgene-negative littermates do not develop any serological and clinical manifestations following immunization. B10.DQ8 transgenic mice develop polyarthritis and Ab's to CII only. The susceptibility to auricular chondritis in NOD.DQ8 mice can be attributed to response to CIX. A higher number of activated cells, CD4 + CD44 h i CD62L l o , and lower regulatory cells CD4 + CD152 + CD25 + were observed in NOD.DQ8 mice compared with B10.DQ8 mice. The NOD.DQ8 mice provide a model of RP with a high disease incidence and multiple organ involvement to investigate putative autoantigen and regulatory cells involved in disease pathogenesis. An experimental model restricted by the human class II molecule will be valuable when studying the role of various collagens in immunologic and pathologic responses in human RP.

Susceptibility to myasthenia gravis (MG) is positively linked to expression of HLA-DQ8 and DR3 molecules and negatively linked to expression of the DQ6 molecule. To elucidate the molecular basis of this association, we have induced experimental autoimmune MG (EAMG) in mice transgenic for HLA-DQ8, DQ6, and DR3, and in DQ8xDQ6 and DQ8xDR3 F(1) transgenic mice, by immunization with human acetylcholine receptor (H-AChR) in CFA. Mice expressing transgenes for one or both of the HLA class II molecules positively associated with MG (DQ8 and DR3) developed EAMG. T cells from DQ8 transgenic mice responded well to three cytoplasmic peptide sequences of H-AChR (alpha320-337, alpha304-322, and alpha419-437), of which the response to alpha320-337 was the most intense. DR3 transgenic mice also responded to this sequence very strongly. H-AChR- and alpha320-337 peptide-specific lymphocyte responses were restricted by HLA class II molecules. Disease resistance in DQ6 transgenic mice was associated with reduced synthesis of anti-AChR IgG, IgG(2b), and IgG(2c) Ab's and reduced IL-2 and IFN-gamma secretion by H-AChR- and peptide alpha320-337-specific lymphocytes. Finally, we show that DQ8 imparts susceptibility to EAMG and responsiveness to an epitope within the sequence alpha320-337 as a dominant trait.

HIV-1-infected patients treated early with combination antiretrovirals respond favorably, but not all maintain viral suppression and improved HIV-specific Th function. To understand if genetic factors contribute to this variation, we prospectively evaluated over 18 months 21 early-treated patients stratified by alleles of class II haplotypes. All seven subjects with the DRB1*13-DQB1*06 haplotype, but only 21% of other subjects, maintained virus suppression at every posttreatment measurement. Following HIV-1 p24 antigen stimulation, PBMCs from patients with this haplotype demonstrated higher mean lymphoproliferation and IFN-gamma secretion than did cells from patients with other haplotypes. Two DRB1*13-restricted Gag epitope regions were identified, a promiscuous one that bound its putative restriction element with nanomolar affinity, and another that mapped to a highly conserved region. These findings suggest that class II molecules, particularly the DRB1*13 haplotype, have an important impact on virologic and immunologic responses. The advantage of the haplotype may relate to selection of key HIV-1 Th1 epitopes in highly conserved regions with avid binding to class II molecules. Eliciting responses to the promiscuous epitope region may be beneficial in vaccine strategies.

The human leukocyte antigen (HLA) restriction of the IgE response to different allergens in humans has been a subject of numerous published studies. However, the role and contribution of specific HLA class II molecules in the pathogenesis of allergic airway inflammation are unknown and difficult to assess. HLA-DQ6 and HLA-DQ8 transgenic mice lacking endogenous mouse class II gene expression were actively immunized and later challenged intranasally with short ragweed (SRW) allergenic extract. The HLA-DQ transgenic mice developed pulmonary eosinophilia and lung tissue damage. We also found an increase in total protein (TP) level and IL-5 production in bronchoalveolar lavage (BAL) fluid and an increase in SRW-specific Th2-type immunoglobulins (IgG1, IgG2b) and total serum IgE levels. Under similar treatment, DQ-negative full-sib control mice were normal. The allergic response could be significantly inhibited or abrogated in HLA-DQ mice by systemic treatment with anti-DQ mAb. The in vivo responses of HLA-DQ6 and HLA-DQ8 mice showed differences in terms of levels of eosinophilia, BAL protein, IL-5 concentration, and lung hyperreactivity to inhaled methacholine. These findings demonstrate the crucial role for specific HLA-DQ molecules in SRW-specific CD4+ T-cell activation and resulting recruitment of eosinophils into the airways. J. Clin. Invest. 103:1707–1717 (1999).

The interaction of the T-cell receptor with the major histocomatibility complex (MHC)-peptide complex is central to T-cell activation. Variation in the nature of the peptide bound within the groove of the MHC molecule may result in an altered T-cell response. Because some naturally processed peptides bound within the groove of the class II MHC molecule are derived from the MHC molecules themselves, we studied the inhibitory effects of synthetic class II MHC peptides on alloimmune responses in vitro. Three peptides derived from a highly conserved region of the class II MHC alpha chains inhibited the rat mixed lymphocyte response (MLR) in a dose-dependent manner, with the human HLA-DQA1 peptide also inhibiting the human and mouse MLR. No effect was seen on mitogen-induced T-cell proliferation. HLA-DQA1 inhibited cytolytic T lymphocyte (CTL) generation in a dose-response fashion, with no reduction in preformed CTL killing, suggesting that the inhibitory effect is targeted at CD4(+) T-cell function. Cell-cycle analysis by flow cytometry showed that restimulation of primed T cells in the presence of HLA-DQA1 resulted in increased apoptosis, whereas unstimulated cells were not affected. These data demonstrate that synthetic peptides derived from highly conserved regions of the class II MHC alpha chain can alter CD4(+) T-lymphocyte alloimmune responses in vitro, and this effect is mediated by the induction of apoptosis in activated T cells.

Certain HLA-DR alleles have been associated with predisposition to human rheumatoid arthritis (RA). There is also evidence that certain HLA-DQ alleles may also be important in determining susceptibility to RA. We have previously demonstrated that mice transgenic for HLA-DQ8, a DQ allele associated with susceptibility to RA, develop severe arthritis after type II collagen immunization. To investigate the influence of polymorphic difference at the DQ loci on susceptibility to arthritis, we generated mice transgenic for HLA-DQ6, an allele associated with a nonsusceptible haplotype. The DQ6 mice were found to be resistant to collagen-induced arthritis. We also assessed the combined effect of an RA-susceptible and an RA nonassociated DQ allele by producing double-transgenic mice expressing DQ6 and DQ8 molecules, representing the more prevalent condition found in humans where heterozygosity at the DQ allele is common. The double-transgenic mice developed moderate CIA when immunized with CII when compared with the severe arthritis observed in DQ8 transgenic mice, much like RA patients bearing both susceptible and nonsusceptible HLA haplotypes. These studies support a role for HLA-DQ polymorphism in human RA.

In this study, a large number of naturally processed peptides was isolated and identified from the human diabetes-susceptible class II MHC molecules HLA-DQ8 (DQA1*0301,DQB1*0302) and from murine I-A species, both of which are expressed in genetically identical APC lines. The peptides presented during the processing of autologous proteins were highly selective in showing sequence specificity, mainly consisting of 1 or more acidic residues at their C terminus. Testing for binding to the MHC molecules revealed that the position 9 (P9) acidic residues of the peptides contributed decisively to binding. For HLA-DQ8, the P1 residue, which was also an acidic amino acid, influenced binding positively. Both HLA-DQ8 and I-A(g7) selected for common peptides that bound in the same register. There was no evidence for selection of peptides having nonspecific or promiscuous binding. Thus, diabetogenic class II MHC molecules are highly selective in terms of the peptides presented by their APCs, and this is governed by the features of their P9 anchor pocket. These results are in striking contrast to those from studies examining synthetic peptide or phage display libraries, in which many peptides were shown to bind.

Levels of insulin autoantibodies (IAA) vary among different first degree relatives of insulin-dependent diabetes mellitus patients, suggesting genetic regulation. We previously reported elevated IAA among DR4-positive at risk relatives. In this study, 72/82 at risk relatives were IAA positive, of whom 75% (54/72) carried DR4 versus 20% (2/10) of IAA-negative relatives (P = 0.0004). However, 69% (18/26) of DR4-negative relatives were IAA positive. Since DR4 did not account for all IAA positivity, we analyzed DQA1 and DQB1 alleles. Homozygosity for DQA1 alleles deriving from the evolutionary lineage 4 (*0401, *0501, *0601) was associated with low IAA levels, while lineage 1-3 alleles (*0101, *0102, *0103, *0201, *0301) correlated with higher levels. Most (93%, 65/70) relatives with lineage 1-3 alleles were IAA positive (mean = 360 +/- 63 SEM nU/ml). Only 7/12 relatives homozygous for lineage 4 alleles were IAA-positive, with lower levels than relatives with lineage 1-3 alleles (mean = 55 +/- 15 SEM nU/ml, P < 0.0001; 7/12 vs 65/70, P = 0.004). The amino acid sequences of lineage 1-3 alleles uniquely share glutamic acid (E) and phenylalanine (F) at positions 40 and 51 (EF alleles). Lineage 4 alleles have glycine (G) and leucine (L) at those positions (GL alleles). 90% (65/72) of IAA-positive relatives had an EF allele, while only 75% (54/72) had DR4 (P = 0.01). Homozygosity for GL alleles (often DQA1 *0501 on DR3 haplotypes) correlated with little or no humoral response to insulin. Thus, HLA-DQB1 GL alleles, or other genes on haplotypes (e.g., DR3) that carry these DQA1 alleles, may confer recessive low responsiveness to insulin.

Autoimmunity has long been linked to myocarditis and its sequela, dilated cardiomyopathy, the leading causes of heart failure in young patients. However, the underlying mechanisms are poorly defined, with most clinical investigations focused on humoral autoimmunity as the target for intervention. Here, we show that the α-isoform of myosin heavy chain (α-MyHC, which is encoded by the gene Myh6) is the pathogenic autoantigen for CD4+ T cells in a spontaneous mouse model of myocarditis. Further, we found that Myh6 transcripts were absent in mouse medullary thymic epithelial cells (mTECs) and peripheral lymphoid stromal cells, which have been implicated in mediating central and peripheral T cell tolerance, respectively. Transgenic expression of α-MyHC in thymic epithelium conferred tolerance to cardiac myosin and prevented myocarditis, demonstrating that α-MyHC is a primary autoantigen in this disease process. Remarkably, we found that humans also lacked α-MyHC in mTECs and had high frequencies of α-MyHC–specific T cells in peripheral blood, with markedly augmented T cell responses to α-MyHC in patients with myocarditis. Since α-MyHC constitutes a small fraction of MyHC in human heart, these findings challenge the longstanding notion that autoimmune targeting of MyHC is due to its cardiac abundance and instead suggest that it is targeted as a result of impaired T cell tolerance mechanisms. These results thus support a role for T cell–specific therapies for myocarditis.

HLA class II alleles were determined using the PCR-RFLP method in Japanese systemic sclerosis (scleroderma) patients with (n = 28) or without (n = 34) anti-topoisomerase I antibodies (anti-topo I). Either the DQB1*0601 or *0301 allele was recognized in all anti-topo I positive patients, compared with 44% of anti-topo I negative patients (P < 0.00001, relative risk [RR] > 41) or 58% of Japanese healthy control subjects (P < 0.00001, RR > 24). Tyrosine at position 26 in the second hypervariable region in the beta 1 domain of the DQB1 gene is common to these two alleles and is not present in any other known DQB1 alleles. We also examined immunoreactivities of anti-topo I positive sera to four different autoantigenic B cell epitopes of topo I molecule that were expressed as recombinant fusion proteins. One major B cell epitope, located within the region corresponding to amino acid residues 74-248, was perfectly associated with the amino acid sequence FLEDR at positions 67-71 in the beta 1 domain of the DRB gene. Two other epitopes, corresponding to 316-441 or 658-700, were associated with the serologically defined HLA-DR52 antigen. Patients with both FLEDR and DR52 demonstrated higher anti-topo I antibody titers. These results suggest that the HLA-DR and DQ genes together control the autoimmune response to topo I in systemic sclerosis.

Newly described distinct associations of HLA class II genes with ulcerative colitis (UC) (DR2) and Crohn's disease (CD) (DR1/DQ5) provide strong evidence for genetic heterogeneity of susceptibility between these two forms of inflammatory bowel disease. A familial distribution of antineutrophil cytoplasmic antibodies (ANCAs, a subclinical marker of UC) in UC families has further implied the existence of heterogeneity within UC. To test the hypothesis that the heterogeneity within UC indicated by ANCAs has a genetic basis that resides within the HLA region, we studied 89 UC cases and an ethnically matched control group (n = 50). Serological and molecular typing techniques were applied to define HLA class II genes (DR, DQ). ANCAs were detected using an enzyme-linked immunosorbent assay, and positive values were confirmed by indirect immunofluorescence. We observed that ANCA-positive UC patients (n = 70) had a significantly increased frequency of DR2 compared with ANCA-negative controls (n = 46) (44% vs 22%, P = 0.01). In contrast, the frequency of DR2 in ANCA-negative UC cases (21%) was virtually identical to that in controls (22%, P = 0.9). Furthermore, the ANCA-negative UC patients had an increase in the DR4 allele compared with ANCA-positive UC (P = 0.004). Thus, with the combination of a subclinical marker (ANCAs) and molecular genetic markers, genetic heterogeneity has been demonstrated within UC: ANCA-positive UC associated with DR2, and ANCA-negative UC likely associated with DR4.

Multiple sclerosis (MS) is an autoimmune disease in which myelin proteins have been implicated as autoantigens recognized by pathogenic autoreactive T cells. To study the relationship between human myelin basic protein (hMBP) and HLA alleles associated to MS susceptibility, such as DRB1*1501, the binding of synthetic peptides spanning the entire hMBP sequence to 10 purified HLA-DR molecules was determined. All the hMBP peptides tested showed binding affinity for at least one of the DR molecules analyzed, but three hMBP peptides, included in sequences 13-32, 84-103, and 144-163 were found capable of binding to three or more DR molecules. The hMBP peptide 84-103 was the most degenerate in binding, in that it bound to 9 out of 10 DR molecules tested. Interestingly, it bound with highest affinity to DRB1*1501 molecules. To correlate the binding pattern of hMBP peptides to HLA class II molecules with their recognition by T cells, 61 hMBP-specific T cell lines (TCL) were established from the peripheral blood of 20 MS patients, who were homozygous, heterozygous, or negative for DRB1*1501. Analysis of hMBP epitopes recognized by these TCL and their HLA restriction demonstrated a very good correlation between binding data and T cell proliferation to hMBP peptides. Although virtually all hMBP peptides tested could be recognized by at least one TCL from MS patients, three immunodominant T cell epitopes were apparent among the TCL examined, corresponding exactly to the hMBP peptides capable of binding to several DR molecules. No major difference could be detected in the recognition of immunodominant hMBP peptides by TCL from DRB1*1501 positive or negative MS patients. These results have implications for the role of hMBP as relevant autoantigen, and of DRB1*1501 as susceptibility allele in MS.

The mechanisms responsible for skin lesions during acute graft-vs.-host disease (aGVHD) after allogeneic bone marrow transplantation (BMT) are poorly understood. The exact role of various effector cell populations and "major" (particularly HLA-DP) or "minor" antigens as target molecules is not known. To investigate the nature of cells responsible for tissue injury, we cultured T cells from skin biopsy first with interleukin 2 (IL-2) alone and then in polyclonal activation conditions to avoid in vitro antigenic sensitization before specificity testing. We applied this method to two biopsies performed during aGVHD after semiallogeneic BMT and obtained cytotoxic T cells against four graft mismatches: CD8+ T cells against HLA-A2.2 and HLA-B27 and CD4+ T cells against HLA-DP101 and HLA-DP401. This demonstrates that T cells with documented specificity can be obtained from an aGVHD lesion without antigenic selection. Moreover, these data directly implicate DP as a potential target antigen for aGVHD.

Previous studies in Caucasians with progressive systemic sclerosis (PSS) have suggested associations of antitopoisomerase I (antitopo I) autoantibodies with either serologically defined HLA-DR2 or DR5. To better define class II HLA associations with the antitopo I response, 161 PSS patients (132 Caucasians and 29 American blacks) were studied for antitopo I autoantibodies by immunodiffusion and immunoblotting, and their HLA-DRB1, DRB3, DQA1, and DQB1 alleles were determined by restriction fragment length polymorphic analysis and DNA oligotyping. Among Caucasians with antitopo I, HLA-DR5(DRB1*1101-*1104), DRB3*0202 and DQw3 (DQw7,8,9) were significantly increased in frequency. In American blacks, however, only HLA-DQB1*0301(DQw7) was significantly increased. The presence of HLA-DQB1*0301(DQw7) and other HLA-DQB1 alleles bearing the uncharged polar amino acid residue tyrosine at position 30 of the outermost domain was found in all antitopo I-positive Caucasian PSS patients compared with 66% of antitopo I-negative PSS patients (pc = 0.007) and 70% of normal controls (pc = 0.008), as well as all antitopo I-positive black patients. The association with HLA-DQB1 was independent of HLA-DR5(DRB1*1101-*1104) or any other HLA-DRB1, DRB3, or DQA1 alleles. Alternative or additional candidate epitopes for this autoimmune response include alanine at position 38 and threonine at position 77 of these same DQB1 alleles. These data suggest that genetic predisposition to the antitopo I response in PSS is associated most closely with the HLA-DQB1 locus.

Autoantibodies to phospholipids (APA) occur frequently in systemic lupus erythematosus (SLE) and other autoimmune disorders and predispose to intravascular thromboses. Major histocompatibility complex (MHC) class II alleles (HLA-DR and DQ) were determined by restriction fragment length polymorphisms (RFLP) in 20 patients with APA (lupus anticoagulant). HLA-DQw7 (DQB1*0301), linked to HLA-DR5 and -DR4 haplotypes, occurred in 70% and was significantly increased compared to 139 race-matched normal controls (P = 0.002, P corrected [pc] = 0.05, odds ratio [OR] = 5.1). Moreover, the frequency of HLA-DQw7 was significantly higher in SLE patients with APA as compared with patients without APA but with other autoantibodies, including anti-Ro and La (P = 0.0001, pc = 0.002, OR = 10.7), anti-Ro alone (P = 0.001, pc = 0.02, OR = 11.2), anti-dsDNA (P = 0.001, pc = 0.02, OR = 7.1), and possibly anti-Sm (P = 0.04, pc = NS, OR = 6.8) and anti-nRNP (U1-RNP) (P = 0.01, pc = NS, OR = 7.8). The DQB1*0301 allele of DQw7 showed the strongest association, while the frequencies of the DQA1*0301 (45%) and DQA1*0501 (50%) alleles did not differ from the controls. Among the HLA-DQB1*0301 (DQw7) negative patients, all possessed HLA-DQw8 (DQB1*0302) and/or HLA-DQw6 (DQB1*0602 or DQB1*0603) alleles. The HLA-DQB1*0301 chain shares an identical seven amino acid sequence with DQB1*0302, *0602, and *0603 chains in the third hypervariable region of the HLA-DQ molecule. This candidate "epitope" may play a role in mediating an autoimmune response to APA.

To directly compare clinical side effects and biological response modification, IFN-beta ser, IFN-gamma, or the combination of IFN-beta ser plus IFN-gamma was administered to 21 cancer patients. Each IFN or the combination was given intravenously on days 1, 8, and 15 in varied order. Each IFN and the combination resulted in significant (P less than 0.05) modulation of IFN-induced proteins. IFN-beta ser was more effective than IFN-gamma in enhancing 2-5A synthetase activity (P = 0.001). IFN-gamma was more effective than IFN-beta ser in enhancing serum beta 2 microglobulin expression (P = 0.05) and indoleamine dioxygenase activity, as assessed by decreased serum tryptophan (P = 0.03). The combination enhanced tryptophan catabolism more effectively than IFN-beta ser in a dose-dependent manner (P less than 0.03). IFN-beta ser/IFN-gamma did not potentiate natural killer cells or antibody-dependent cellular toxicity (ADCC). IFN-beta ser/IFN-gamma enhanced monocyte guanylate cyclase activity, as assessed by serum neopterin, more effectively than IFN-gamma alone (P = 0.005). Both IFNs and the combination resulted in increases in HLA class II expression on monocytes. However, no significant difference in the level of induction of HLA DQ and HLA DR expression between IFN-beta ser/IFN-gamma and either IFN-beta ser or IFN-gamma was noted. Although frequency and servity of side effects of IFN-beta ser, IFN-gamma, or the combination were dose related, induction of induced proteins (with exception of influences on tryptophan catabolism) were not a function of dose administered over the 10-fold range. Continued treatment with the combination intravenously three times a week for 4 wk sustained but did not further potentiate, most of the changes in interferon-induced proteins. Thus, IFN-beta ser and IFN-gamma each resulted in effective and essentially equivalent patterns of induction of induced proteins. When combined, however, these IFNs did not result in potentiation of biological response modification in vivo.

Activated immune cells release cytokines which modulate the activity of bone cells in vitro. Expression of major histocompatibility complex (HLA in humans) class II determinants on bone surface cells may be important in local immune cell activation. In this study, expression of HLA-DR and DQ by cultured human bone cells (HBC) derived from normal trabecular bone surfaces was assessed by fluorescence-activated cell sorter (FACS) analysis and immunoperoxidase techniques using monoclonal antibodies. A subset of HBC (10-30%) expressed DR constitutively while 5-15% displayed DQ during long-term culture. HBC lacked a number of monocyte and lymphocyte markers. In addition, both DR+ and DR- HBC (FACS separated) produced osteocalcin stimulated by 1,25-dihydroxyvitamin D2 (1,25(OH)2D3). This suggests that both phenotypes belong to the osteoblast lineage. The number of DR+ HBC was increased by interferon-gamma (IFN gamma; 40-95% DR+ cells) whereas DQ+ HBC remained unchanged or was slightly increased (5-20% DQ+ cells). Moreover, 1,25(OH)2D3 enhanced IFN gamma-induced DR expression and at high concentration (10(-7) M) augmented DR expression by itself. Other major osteotropic factors, parathyroid hormone, interleukin 1, and calcitonin, did not affect HBC DR expression. The findings suggest that HBC may participate in activation of the immune system and that some osteotropic factors may regulate this function.

The purified human monocytes of a responding donor preincubated with heat-inactivated serum T1264 or T1295 derived from pregnant women for 30 min at 37 degrees C expressed allogeneic suppressive effects on the proliferative response of the lymphocytes from the same donor in the allogeneic mixed lymphocyte reaction (MLR). The pregnancy serum in our experiments was found not to contain any antibodies to DR and DQ antigens on monocytes of the responding donor. Accordingly, the suppressive effects mediated by monocytes were not based on the blocking of DR and DQ antigens on monocytes of the responding donor by DR and DQ antibodies in the serum. These highly reproducible allogeneic suppressive effects by monocytes of the responding donor were demonstrated in the MLR specific for DRw9-positive stimulating cells, whereas no inhibition was seen in the cultures with other stimulating cells of different DR phenotypes. Additionally, these suppressive effects appeared on the monocytes of a DR2-positive responding donor, but not on the monocytes of a DR2-negative responding donor. These suppressive effects were abolished when the absorbed pregnancy serum by monocytes of the DR2-positive responding donor was used. In this suppression phenomenon that we discovered, monocytes of the responding donor appear to act as regulatory cells on the proliferative response of the allogeneic MLR. This regulatory function of monocytes could be expressed through the specific molecules distinct from DR and DQ determinants on monocytes in cooperation with antibodies (IgG class) in the pregnancy serum.

A BamHI 3.7-kilobase (kb) fragment detected by an HLA-DQ beta-chain complementary DNA (cDNA) probe and negatively associated with insulin-dependent diabetes mellitus (IDDM) was cloned and sequenced to localize the polymorphism to BamHI sites in intervening sequences of an HLA-DQ beta-chain gene. A probe of the first intervening sequence (IVS 1) showed the BamHI 3.7-kb fragment in 6 of 17 HLA-DR3/4 controls but in 0 of 13 DR-identical IDDM patients. All IDDM patients (13 of 13) had BamHI fragments of 12 and 4 kb, detected in 9 of 17 controls (P less than 0.02). The simple restriction fragment length polymorphism pattern of the IVS 1 probe was exploited by comparing 113 IDDM patients with 177 healthy controls to show increased prevalences in IDDM of the 12-kb (P less than 0.0001) and 4-kb (P less than 0.0001) fragments. In IDDM patients younger than 20 yr at onset, 98% were 12- and/or 4-kb positive, compared with 63% of controls (P less than 0.0001), giving a relative risk of 91.8 for individuals with both fragments. The 12-kb fragment was linked to HLA-DR4, and the 4-kb fragment to HLA-DR3. Both serologic markers were split and a non-DR3/non-DR4 IDDM patient was 4-kb positive. HLA-DQ seems therefore closer, than HLA-DR, to an IDDM susceptibility gene.

HLA-DR4 is associated with insulin-dependent diabetes mellitus (IDDM) in many populations. Many recent studies suggest that the DR4 effect is really due to DQ3.2, an allele of the nearby DQB1 locus. We used T cell clones, MAb, and allele-specific oligonucleotides to test IDDM and control subjects for DR4 subtypes (Dw4, Dw10, Dw13, and Dw14) and for DR4-associated DQB1 alleles (DQ3.1 and DQ3.2). We find that (a) IDDM is approximately equally associated with alleles of the DRB1 locus (Dw4 and Dw10, combined relative risk, RR = 6.4) and the DQB1 locus (DQ3.2, RR = 5.9); and (b) there is significant interaction, in a statistical sense, between these DR and DQ alleles in IDDM. The only IDDM-associated DR4 haplotypes were those carrying the IDDM-associated alleles at both loci (RR = 12.1); haplotypes with Dw4 or 10 but not DQ3.2, or vice versa, had a RR less than 1. Alternative explanations include: (a) that susceptibility requires specific allelic products of both DR and DQ loci; (b) that the combination of certain DR and DQ alleles marks haplotypes with the true susceptibility allele at a third locus; or (c) that Dw4 and 10 mark haplotypes with an allele at another locus that interacts with DQ3.2. As discussed, this third locus is unlikely to be DQA1 (DQ alpha). The data thus are not easily reconciled with an exclusive effect of HLA-DQ. This information increases our ability to predict IDDM by genetic typing: in the population studied, heterozygotes DR3/[DQ3.2, Dw4] or DR3/[DQ3.2, Dw10] had a relative risk of 38.0 and an absolute risk of 1 in 15.