Soluble HLA in human body fluids

Engineered HCMV-infected APCs enable the identification of new immunodominant HLA-restricted epitopes of anti-HCMV T-cell immunity

Complications due to HCMV infection or reactivation remain a challenging clinical problem in immunocompromised patients, mainly due to insufficient or absent T-cell functionality. Knowledge of viral targets is crucial to improve monitoring of high-risk patients and optimise antiviral T-cell therapy. To expand the epitope spectrum, genetically-engineered dendritic cells (DCs) and fibroblasts were designed to secrete soluble (s)HLA-A*11:01 and infected with an HCMV mutant lacking immune evasion molecules (US2-6 + 11). More than 700 HLA-A*11:01-restricted epitopes, including more than 50 epitopes derived from a broad range of HCMV open-reading-frames (ORFs) were identified by mass spectrometry and screened for HLA-A*11:01-binding using established prediction tools. The immunogenicity of the 24 highest scoring new candidates was evaluated in vitro in healthy HLA-A*11:01+/HCMV+ donors. Thus, four subdominant epitopes and one immunodominant epitope, derived from the anti-apoptotic protein UL36 and ORFL101C (A11SAL), were identified. Their HLA-A*11:01 complex stability was verified in vitro. In depth analyses revealed highly proliferative and cytotoxic memory T-cell responses against A11SAL, with T-cell responses comparable to the immunodominant HLA-A*02:01-restricted HCMVpp65NLV epitope. A11SAL-specific T cells were also detectable in vivo in immunosuppressed transplant patients and shown to be effective in an in vitro HCMV-infection model, suggesting their crucial role in inhibiting viral replication and improvement of patient's outcome. The developed in vitro pipeline is the first to utilise genetically-engineered DCs to identify naturally presented immunodominant HCMV-derived epitopes. It therefore offers advantages over in silico predictions, is transferable to other HLA alleles, and will significantly expand the repertoire of viral targets to improve therapeutic options.

Soluble HLA peptidome: A new resource for cancer biomarkers

Using circulating molecular biomarkers to screen for cancer and other debilitating disorders in a high-throughput and low-cost fashion is becoming increasingly attractive in medicine. One major limitation of investigating protein biomarkers in body fluids is that only one-fourth of the entire proteome can be routinely detected in these fluids. In contrast, Human Leukocyte Antigen (HLA) presents peptides from the entire proteome on the cell surface. While peptide-HLA complexes are predominantly membrane-bound, a fraction of HLA molecules is released into body fluids which is referred to as soluble HLAs (sHLAs). As such peptides bound by sHLA molecules represent the entire proteome of their cells/tissues of origin and more importantly, recent advances in mass spectrometry-based technologies have allowed for accurate determination of these peptides. In this perspective, we discuss the current understanding of sHLA-peptide complexes in the context of cancer, and their potential as a novel, relatively untapped repertoire for cancer biomarkers. We also review the currently available tools to detect and quantify these circulating biomarkers, and we discuss the challenges and future perspectives of implementing sHLA biomarkers in a clinical setting.

The Potential of Soluble Human Leukocyte Antigen Molecules for Early Cancer Detection and Therapeutic Vaccine Design

Human leukocyte antigen (HLA) molecules are essential for anti-tumor immunity, as they display tumor-derived peptides to drive tumor eradication by cytotoxic T lymphocytes. HLA molecules are primarily studied as peptide-loaded complexes on cell membranes (mHLA) and much less attention is given to their secretion as soluble HLA–peptide complexes (sHLA) into bodily fluids. Yet sHLA levels are altered in various pathologies including cancer, and are thus of high interest as biomarkers. Disconcordance in results across studies, however, hampers interpretation and generalization of the relationship between sHLA levels and cancer presence, thereby impairing its use as a biomarker. Furthermore, the question remains to what extent sHLA complexes exert immunomodulatory effects and whether shifts in sHLA levels contribute to disease or are only a consequence of disease. sHLA complexes can also bear tumor-derived peptides and recent advancements in mass spectrometry now permit closer sHLA peptide cargo analysis. sHLA peptide cargo may represent a “liquid biopsy” that could facilitate the use of sHLA for cancer diagnosis and target identification for therapeutic vaccination. This review aims to outline the contradictory and unexplored aspects of sHLA and to provide direction on how the full potential of sHLA as a quantitative and qualitative biomarker can be exploited.

Membranal and Blood-Soluble HLA Class II Peptidome Analyses Using Data-Dependent and Independent Acquisition

The interaction between HLA class II peptide complexes on antigen-presenting cells and CD4⁺ T cells is of fundamental importance for anticancer and antipathogen immunity as well as for the maintenance of immunological tolerance. To study CD4⁺ T cell reactivities, detailed knowledge of the presented peptides is necessary. In recent years, dramatic advances in the characterization of membranal and soluble HLA class I peptidomes could be observed. However, the same is not true for HLA class II peptidomes, where only few studies identify more than hundred peptides. Here we describe a MS-based workflow for the characterization of membranal and soluble HLA class II DR and DQ peptidomes. Using this workflow, we identify a total of 8595 and 3727 HLA class II peptides from Maver-1 and DOHH2 cells, respectively. Based on this data, a motif-based binding predictor is developed and compared to NetMHCIIpan 3.1. We then apply the workflow to human plasma, resulting in the identification of between 34 and 152 HLA-DR and between 100 and 180 HLA-DQ peptides, respectively. Finally, we implement a data-independent acquisition workflow to increase reproducibility and sensitivity of HLA class II peptidome characterizations.

Soluble major histocompatibility complex molecules in immune regulation: highlighting class II antigens

The involvement of major histocompatibility complex (MHC) antigens in the development and regulation of immune response has been well defined over the years, starting from maturation, antigenic peptide loading, migration to the cell membrane for recognition by the T-cell receptor and recycling for immune response cessation. During this intracellular trafficking, MHC antigens find a way to be excreted by the cells, because they can be found as soluble MHC class I (sMHC-I) and class II (sMHC-II) molecules in all body fluids. Although secretion mechanisms have not been sufficiently studied, sMHC molecules have been shown to display important immunoregulatory properties. Their levels in the serum have been shown to be altered in a variety of diseases, including viral infections, inflammation, autoimmunities and cancer, etc. while they seem to be involved in a number of physiological reactions, including maintenance of tolerance, reproduction, as well as mate choice vis-à-vis species evolution. The present review aims to present the thus far existing literature on sMHC molecules and point out the importance of these molecules in the maintenance of immune homeostasis.

Soluble MHC class II-driven therapy for a systemic lupus erythematosus murine experimental in vitro and in vivo model

Taking into consideration the multiparametric nature of systemic lupus erythematosus (SLE), the severity and variability of symptoms and the lack of effective therapeutic approaches, this study took advantage of the recently described role of soluble major histocompatibility complex class II (sMHCII) molecules in maintaining tolerance to the organism and attempted to apply sMHCII proteins as a treatment to murine SLE experimental models in vitro as well as in vivo. After breaking tolerance to DNA in vitro, which was accompanied by development of specific anti-dsDNA antibodies, syngeneic or allogeneic sMHCII molecules, purified from healthy mouse serum, could significantly reduce the specific antibody levels and drive the system towards immunosuppression, as assessed by specific marker analysis on T cells and cytokine production by flow cytometry and ELISA, respectively. The in vivo experimental model consisted of pristane-induced SLE symptoms to BALB/c mice, which developed maximal levels of anti-dsDNA 2 months after pristane inoculation. Syngeneic or allogeneic sMHCII administration could alleviate pristane-induced symptoms, significantly decrease specific anti-dsDNA antibody production and develop immunosuppression to the host, as manifested by increase of CD4 + CTLA-4 +  and CD4 + CD25 +  cell populations in the spleen. Thus, the results presented in this study introduced the ability of sMHCII proteins to suppress specific autoantigen response, opening new areas of research and offering novel therapeutic approaches to SLE with expanding features to other autoimmune diseases.

Soluble HLA-DR serum levels are associated with smoking but not with acute coronary syndrome

BACKGROUND & AIMS

Elevated soluble HLA-DR (sHLA-DR) serum levels have been reported in HLA class II-associated inflammatory disorders. We have previously shown that the HLA class II allele HLA-DRB1*01 may predispose to acute coronary syndromes (ACS). To our knowledge, sHLA-DR serum levels have not been studied in ACS.

METHODS

sHLA-DR serum levels were measured in 477 ACS patients as cases and 475 area- and sex-matched controls by sandwich enzyme-linked immunosorbent assay. Binary logistic regression and ordinal logistic regression analyses adjusted for clinical parameters were conducted to evaluate the associations of sHLA-DR levels.

RESULTS

ACS patients had lower sHLA-DR serum levels compared to controls (OR = 0.837; 95% CI = 0.704-0.994; p = 0.043). After adjustment for smoking status, this association was no longer significant. This was explained by the notion that current smoking was inversely associated with sHLA-DR levels both in cases (OR = 0.592; 95% CI = 0.553-0.908; p = 0.016) and in controls (OR = 0.356; 95% CI = 0.226-0.563; p = 0.000010). A similar effect was not seen with other cardiovascular risk factors.

CONCLUSIONS

The results indicate, for the first time, that lower sHLA-DR levels are associated with smoking, but not with ACS. This is an important finding because previous studies of sHLA-DR have not accounted for the possible associations between smoking and sHLA-DR levels. Further studies are required to confirm these novel results and explore the mechanisms behind the observed associations.

Soluble MHC-II proteins promote suppressive activity in CD4+ T cells

Soluble MHCII (sMHCII) molecules are present in body fluids of healthy individuals and are considered to be involved in the maintenance of self tolerance, and are also related to various diseases. Their concentration increases during in vivo antigen-specific tolerogenic stimulation and it was recently shown that exosome-mediated tolerance is MHCII dependent. At the cellular level, sMHCII proteins compete with membrane MHCII for T-cell receptor binding on CD4(+) T cells. Immunoaffinity purification techniques isolated sMHCII antigens from the serum of human serum albumin (HSA) -tolerant mice as a single highly glycosylated protein of ~ 60,000 molecular weight, specifically interacting with anti-class II antibodies in Western blotting and ELISA. Mass spectroscopy showed that these sMHCII proteins were loaded with the tolerogenic peptide as well as multiple self peptides. At the cellular level, sMHCII suppressed antigen-specific, and to a lesser degree antigen-non-specific, spleen cell proliferation and induced CD25 in naive T cells. In T cells activated by antigen-seeded macrophages, sMHCII decreased CD28 and increased CTLA-4 protein expression, while decreasing interleukin-2 and increasing interleukin-10 production. In this case, sMHCII proteins were shown to decrease ZAP-70 and LAT phosphorylation. The results presented here for the first time provide evidence for the role of sMHCII proteins in immune response suppression and maintenance of tolerance, revealing novel regulatory mechanisms for immune system manipulation.

The Role of HLA in MS Susceptibility and Phenotype

One of the most consistent findings in multiple sclerosis (MS) is that development of MS is linked with carriage of the class II human leucocyte antigen (HLA) molecule HLA-DRB1*15:01; around 60 % of Caucasian MS patients carry this allele compared to 25-30 % of ethnically matched healthy individuals. However, other HLA molecules have also been linked to the development of MS. In this chapter, the association between different HLA types and susceptibility to MS will be reviewed, and other linkages between the carriage of specific HLA molecules and clinical and experimental findings in MS will be considered.

MHC class I antigen processing and presenting machinery: organization, function, and defects in tumor cells

The surface presentation of peptides by major histocompatibility complex (MHC) class I molecules is critical to all CD8(+) T-cell adaptive immune responses, including those against tumors. The generation of peptides and their loading on MHC class I molecules is a multistep process involving multiple molecular species that constitute the so-called antigen processing and presenting machinery (APM). The majority of class I peptides begin as proteasome degradation products of cytosolic proteins. Once transported into the endoplasmic reticulum by TAP (transporter associated with antigen processing), peptides are not bound randomly by class I molecules but are chosen by length and sequence, with peptidases editing the raw peptide pool. Aberrations in APM genes and proteins have frequently been observed in human tumors and found to correlate with relevant clinical variables, including tumor grade, tumor stage, disease recurrence, and survival. These findings support the idea that APM defects are immune escape mechanisms that disrupt the tumor cells' ability to be recognized and killed by tumor antigen-specific cytotoxic CD8(+) T cells. Detailed knowledge of APM is crucial for the optimization of T cell-based immunotherapy protocols.

Elevated soluble HLA II protein levels in patients with alpha-1 antitrypsin deficiency with or without COPD

Elevated levels of human leukocyte antigen (HLA) proteins have been reported in several pathologic conditions that are associated with increased concentrations of white blood cells (e.g., infection, inflammation, and lymphoproliferative disorders). The mechanisms by which HLA proteins are solubilized from cell membranes are insufficiently understood. We hypothesized that HLA proteins may be cleaved from cell membranes by insufficiently inhibited leukocytic elastase, as expected in alpha-1 antitrypsin deficiency (A1ATD), resulting in elevated plasma levels of soluble HLA (sHLA) proteins. Using an enzyme-linked immunosorbent assay, we measured sHLA II levels in the peripheral blood of patients with A1ATD with or without co-existing chronic obstructive pulmonary disease (COPD), with COPD only, and in a control group. Mean (±SD) sHLA II plasma levels were 110 ± 200 pg/mL in patients with A1ATD and COPD (Group 1), 10 ± 30 pg/mL in patients with COPD without A1ATD (Group 2), 70 ± 90 pg/mL in patients with A1ATD without COPD (Group 3), and 10 ± 30 pg/mL in healthy donors (Group 4). Soluble HLA II plasma levels were significantly higher in Group 1 (P = .001) and Group 3 (P = .002) versus Group 4. Our preliminary results suggest that leukocytic elastase and probably other proteinases solubilize HLA proteins from cell membranes. This mechanism would operate in inflammation with elevated leukocytic elastase levels but more so with inflammation and A1ATD, where elastase would be insufficiently inhibited. If this mechanism is verified, plasma sHLA levels could potentially be used to measure cell damage due to proteinases and, therefore, for monitoring the therapeutic efficacy of alpha-1 antitrypsin (A1AT) augmentation therapy.

Tumor escape mechanisms: potential role of soluble HLA antigens and NK cells activating ligands

The crucial role played by human leukocyte antigen (HLA) antigens and natural killer (NK)-cell-activating ligands in the interactions of malignant cells with components of the host's immune system has stimulated interest in the characterization of their expression by malignant cells. Convincing evidence generated by the immunohistochemical staining of surgically removed malignant lesions with monoclonal antibodies recognizing HLA antigens and NK-cell-activating ligands indicates that the surface expression of these molecules is frequently altered on malignant cells. These changes appear to have clinical significance because in some types of malignant disease they are associated with the histopathological characteristics of the lesions as well as with disease-free interval and survival. These associations have been suggested to reflect the effect of HLA antigen and NK-cell-activating ligand abnormalities on the interactions of tumor cells with antigen-specific cytotoxic T lymphocytes (CTL) and with NK cells. Nevertheless, there are examples in which disease progresses in the face of appropriate HLA antigen and/or NK-cell-activating ligand as well as tumor antigen expression by malignant cells and of functional antigen-specific CTL in the investigated patient. In such scenarios, it is likely that the tumor microenvironment is unfavorable for CTL and NK cell activity and contributes to tumor immune escape. Many distinct escape mechanisms have been shown to protect malignant cells from immune recognition and destruction in the tumor microenvironment. In this article, following the description of the structural and functional characteristics of soluble HLA antigens and NK-cell-activating ligands, we will review changes in their serum level in malignant disease and discuss their potential role in the escape mechanisms used by tumor cells to avoid recognition and destruction.

Serum levels of soluble HLA and IL-2R molecules in patients with urogenital chlamydia infection

Cellular immunity plays a central role in immune response to chlamydial infection, and soluble forms of immune cell membrane antigens take part in the regulation of immune response. Using an immunoenzymatic method, we determined serum levels of soluble HLA molecules (sHLA-I and sHLA-DR) and soluble CD25 molecules (sCD25) in patients with genital chlamydial infection. Specimens from patients with nonspecific inflammation of the urogenital tract were studied and healthy volunteers served as controls. We revealed that serum levels of sHLA-DR and sCD25 increased 3.5- and 2.3-fold, respectively, during chlamydial infection, while the levels of sHLA-I were not changed. Nonspecific inflammation of the urogenital tract was characterized by a 1.5-fold increase in sHLA-I, a 1.6-fold decrease in sCD25, and no changes of sHLA-DR levels in comparison with healthy volunteers. We concluded that Th1 immune responses might dominate during genital chlamydial infection contrary to the state of nonspecific inflammation of urogenital tract.

Saliva soluble HLA as a potential marker of response to interferon-beta 1a in multiple sclerosis: a preliminary study

Objective

Potential surrogate markers of disease activity, including response to therapy, are particularly important in a neurological disorder such as multiple sclerosis (MS) which often has a fluctuating course. Based upon previous studies in our laboratory, we hypothesized that measurement of soluble HLA (sHLA) molecules class II in saliva of MS patients can serve as marker of therapeutic response to high dose interferon beta-1a.

Methods

We measured the expression patterns of sHLA-II in saliva in 17 patients with relapsing/remitting MS and compared the results to clinical course and brain MRI. For comparison purposes we also assayed the saliva sHLA-II levels in 53 normal control subjects. Solid phase ELISA was used for measurement of sHLA-I and sHLA-II concentrations at baseline and after three and six months of treatment with high dose interferon beta-1a (IFN β-1a).

Results

The mean saliva sHLA-ll levels in MS patients was significantly higher than normal controls (354 ± 42 unit/mL vs. 222 ± 18 unit/mL, t= 8.16, p < 0.003). Comparison of saliva sHLA-II values before and after treatment with IFN β-1a revealed a consistent increase in mean concentration. The increase in saliva sHLA-II values (354 ± 42 unit/mL at baseline versus 821 ± 86 unit/mL at 3 months and 776 ± 63 unit/mL at 6 months, in unit/mL, p < 0.001 for both comparisons) was associated with a stable clinical course and a decline of the number of contrast-enhancing lesions on brain MRI. Comparison of the volume of T2-weighted lesions and the number of black holes on T1-weighted images did not reveal any significant changes (during pre-treatment versus post-treatment month 6) or any correlations with saliva sHLA-II levels. Saliva sHLA-I levels were not detectable.

Conclusion

Serial measurement of saliva sHLA-II may serve as a potential marker of therapeutic response to IFN β-1a. Larger clinical studies involving more RRMS patients over longer periods of time are needed to further test the significance and value of saliva sHLA-II as an accurate marker of therapeutic response to beta-interferons.

Soluble HLA revisited

The goal of this editorial is to revisit soluble human leukocyte antigens (sHLA) and to highlight the findings reported by Albitar et al. in this issue on the relation between sHLA levels in Non-Hodgkin's Lymphoma (NHL) and Hodgkin's Disease (HD). We will review key aspects of sHLA including soluble HLA-G, which has received a lot of attention in recent publications. We will then address the role of sHLA in lymphoproliferative diseases and in solid organ tumors. Lastly, we will comment on the results of Albitar et al. and their relevance to clinical application in NHL.

Position-dependent repression and promotion of DQB1 intron 3 splicing by GGGG motifs

Alternative splicing of HLA-DQB1 exon 4 is allele-dependent and results in variable expression of soluble DQbeta. We have recently shown that differential inclusion of this exon in mature transcripts is largely due to intron 3 variants in the branch point sequence (BPS) and polypyrimidine tract. To identify additional regulatory cis-elements that contribute to haplotype-specific splicing of DQB1, we systematically examined the effect of guanosine (G) repeats on intron 3 removal. We found that the GGG or GGGG repeats generally improved splicing of DQB1 intron 3, except for those that were adjacent to the 5' splice site where they had the opposite effect. The most prominent splicing enhancement was conferred by GGGG motifs arranged in tandem upstream of the BPS. Replacement of a G-rich segment just 5' of the BPS with a series of random sequences markedly repressed splicing, whereas substitutions of a segment further upstream that lacked the G-rich elements and had the same size did not result in comparable splicing inhibition. Systematic mutagenesis of both suprabranch guanosine quadruplets (G(4)) revealed a key role of central G residues in splicing enhancement, whereas cytosines in these positions had the most prominent repressive effects. Together, these results show a significant role of tandem G(4)NG(4) structures in splicing of both complete and truncated DQB1 intron 3, support position dependency of G repeats in splicing promotion and inhibition, and identify positively and negatively acting sequences that contribute to the haplotype-specific DQB1 expression.

Soluble HLA measurement in saliva and cerebrospinal fluid in Caucasian patients with multiple sclerosis: a preliminary study

Background

Measurement of soluble HLA in body fluids has a potential role in assessing disease activity in autoimmune disorders.

Methods

We applied a solid phase, enzyme-linked immunoassay to measure soluble HLA class I (sHLA-I) and class II (sHLA-II) molecules in the saliva and cerebrospinal fluid (CSF) in 13 untreated patients with relapsing-remitting form of multiple sclerosis (MS). For comparison purposes, we also studied saliva from 53 healthy subjects.

Results

Saliva from normal controls had detectable sHLA-I levels in 41 of 53 individuals studied, with values ranging from 9–100 ng/ml (mean = 41 ± 2.8 ng/ml). sHLA-I was undetectable in the saliva in 11 of 13 MS patients, and in none of the CSF specimens. In contrast, mean sHLA-II concentration in the saliva of MS patients was significantly increased compared to controls (386 ± 52 unit/ml vs. 222 ± 18.4 unit/ml, t = 8.68, P < 0.005). The mean CSF sHLA-II level (369 ± 16 unit/ml) was equivalent to the mean sHLA-II concentration measured in saliva (mean = 386 ± 52 unit/ml) (P = 0.7). In patients with brain magnetic resonance imaging (MRI) enhancing lesions (n = 5), reflective of more active disease, CSF sHLA-II averaged 356 ± 26 unit/ml compared to 380 ± 51 in saliva. Similarly, in patients with non-enhancing lesions (n = 8), CSF sHLA-II averaged 377 ± 18 unit/ml compared to 390 ± 77 unit/ml in saliva. Thus, the mean sHLA-II concentration in saliva and CSF was essentially equivalent for MS patients with or without enhancing plaques.

Conclusion

Our data suggest that the measurement of soluble HLA in saliva, specifically sHLA-II, correlates with the level found in the CSF. Therefore, if sHLA correlates with disease activity in MS, as has been proposed, saliva measurements provide a noninvasive correlate of CSF measurement.

Branch site haplotypes that control alternative splicing

We show that the allele-dependent expression of transcripts encoding soluble HLA-DQbeta chains is determined by branchpoint sequence (BPS) haplotypes in DQB1 intron 3. BPS RNAs associated with low inclusion of the transmembrane exon in mature transcripts showed impaired binding to splicing factor 1 (SF1), indicating that alternative splicing of DQB1 is controlled by differential BPS recognition early during spliceosome assembly. We also demonstrate that naturally occurring human BPS point mutations that alter splicing and lead to recognizable phenotypes cluster in BP and in position -2 relative to BP, implicating impaired SF1-BPS interactions in disease-associated BPS substitutions. Coding DNA variants produced smaller fluctuations of exon inclusion levels than random exonic substitutions, consistent with a selection against coding mutations that alter their own exonization. Finally, proximal splicing in this multi-allelic reporter system was promoted by at least seven SR proteins and repressed by hnRNPs F, H and I, supporting an extensive antagonism of factors balancing the splice site selection. These results provide the molecular basis for the haplotype-specific expression of soluble DQbeta, improve prediction of intronic point mutations and indicate how extraordinary, selection-driven DNA variability in HLA affects pre-mRNA splicing.

Mutation analysis of BrCA1, BrCA2, and p53 versus soluble HLA class I and class II in a case of familial endometriosis

OBJECTIVE

To investigate possible correlation(s) between mutations of BrCA1, BrCA2, and p53 genes versus soluble HLA expression in familial endometriosis.

DESIGN

Mutation analysis.

SETTING

University teaching departments and hospital.

PATIENT(S)

A family with seven women in two generations with familial endometriosis.

INTERVENTION(S)

Mutation analysis of BrCA1, BrCA2, and p53 genes.

MAIN OUTCOME MEASURE(S)

A point mutation of the BrCA1 gene appears to inhibit soluble HLA secretion.

RESULT(S)

Among the three genes examined, only the BrCA1 gene showed a T to A mutation at position 3232 that correlates with total abolishment of both class I and class II antigen release.

CONCLUSION(S)

A possible correlation between a BrCA1 mutation and soluble HLA expression appears to exist. The mutation is not stage dependent and seemingly influences the secretion of both class I and class II antigens that are totally absent from the serum of only one family member.

Human leukocyte antigen-A, -B, -C and -DR alleles and soluble human leukocyte antigen class I serum level in Ménière's disease

Previous studies have suggested that many human leukocyte antigen (HLA)-A, -B, -C and -DR alleles are associated with Ménière's disease (MD), an inner ear disorder with a proposed autoimmune etiopathogenesis. Despite some discrepancies many reports are in agreement with a hypothesis suggesting an influence of serologically detected HLA-C products in the susceptibility to the disease. To confirm these data we investigated the distribution of HLA-A, -B, -C and -DR antigens that well define the HLA polymorphism using DNA typing. Furthermore, as autoimmune factors have been claimed to play a role in MD, we investigated the serum level of soluble HLA class I (sHLA-I). Molecular typing of HLA class I and II was performed using polymerase chain reaction sequence-specific primers in 41 patients affected by MD, 34 patients affected by other inner ear diseases (OIDs) and 101 healthy subjects. An ELISA technique was employed to investigate the serum level of sHLA-I in 17 MD patients, 10 OID patients and 83 healthy subjects. The results showed a significantly increased frequency of the Cw*07 specificities in MD patients when compared to OID patients (63.4% vs 32.3%; p = 6.9 x 10(-3); relative risk [RR] = 3.6) and healthy subjects (63.4% vs 35.6%; p = 2.28 x 10(-3); RR = 3.1). The sHLA-I concentrations detected in sera did not differ significantly between MD patients (616 +/- 271 ng/ml), OID patients (570 +/- 307 ng/ml) and healthy subjects (518 +/- 340 ng/ml).

Soluble HLA-DR levels in serum are associated with therapy and genetic factors in rheumatoid arthritis

As rheumatoid arthritis (RA) is an HLA-DR associated autoimmune disease and soluble HLA-DR (sHLA-DR) molecules have the capacity to regulate the immune response, we studied the sHLA-DR levels in RA patients in view of therapy modalities and clinical and biologic parameters of disease activity. For this sHLA-DR concentrations from 87 RA patients were determined by a sensitive enzyme-linked immunoabsorbent assay (ELISA) format. There was a weak but significant correlation between sHLA-DR levels and disease activity (r 0.186 to 0.287, p < 0.004 to < 0.001). The mean serum sHLA were not significantly different between groups with or without corticosteroids, or undergoing therapy with different disease modifying antirheumatic drugs. However, patients treated with a combination of methotrexate and prednisolone have lower sHLA-DR (206 +/- 21 ng/ml, n = 34) compared with the mean value for all other samples (306 +/- 16, n = 217, p < 0.001). This corresponded with significantly lower EULAR pain and swelling scores, ESR and rheumatoid factor (RF) by latex fixation (p < 0.02 to 0.001) in the former, compared with the latter group. Furthermore, sHLA-DR was, respectively, 267 +/- 15 ng/ml (n = 182) in samples from patients treated with nonsteroidal anti-inflammatory drugs (NSAIDs), and 358 +/- 31 (n = 72) without NSAIDs (p < 0.01). Lower sHLA-DR with NSAIDs contrasted with significantly higher scores for pain, swelling, CRP, and RF by latex fixation and by Waaler-Rose test (p < 0.05 to 0.001). Comparison of subgroups with or without the shared epitope of RA disease (Q)R/KRAA within the HLA-DR beta1-chain confirmed significantly higher parameters of disease activity and sHLA-DR in the presence of this disease associated epitope in our patients. Different mechanisms appear to be involved in sHLA-DR production or release, as their level correlates positively with disease activity under combined therapy with corticosteroids and methotrexate, but decreases with higher disease activity in patients treated with NSAIDs.

The possible anti-inflammatory role of circulating human leukocyte antigen levels in women with endometriosis after treatment with danazol and leuprorelin acetate depot

BACKGROUND

Endometriosis is defined as an inflammatory condition of the female reproductive tract, a state often associated with infertility and miscarriage. Many exogenously administered factors (treatments) control the disease via as yet unknown pathways. Possible candidate molecules involved in these mechanisms could be the serum-soluble human leukocyte antigens (sHIA) that have been detected in a variety of human body fluids and that are associated with several diseases.

AIMS

We here examine how danazol and leuprorelin acetate depot treatments exert their anti-inflammatory action. It is plausible that subtle alterations mediated by these treatments and in relation to sHLA may explain the pathophysiology of endometriosis and provide insights towards new therapeutic protocols.

METHODS

Indirect enzyme-linked immunosorbent assay (ELISA), using specific monoclonal antibodies, determined serum-soluble class-I and class-II HLA levels. ELISA readings from treated women were compared with normal healthy subjects.

RESULTS

Serum-soluble class-I and class-II HLA levels are statistically significantly lower (P < 0.001) in women with endometriosis than in the control groups. However, danazol but not leuprorelin acetate depot administration augments soluble HLA class I and class II (P < 0.01 and P < 0.001, respectively) to normal levels during the treatment period, an increase that may account for the anti-inflammatory effect and the remission observed.

CONCLUSIONS

It is shown that one of the underlying causes of endometriosis may be the lack of both circulating class-I and class-II antigen levels. Danazol administration acts via an induced release of these antigens, whose presence correlates with the degree of the inflammatory alleviation obtained. We thus provide evidence that the inflammatory state of the disease appears to be associated with soluble HLA levels because, 3 months after ceasing therapy, the circulating antigens in the serum return to the same levels that correspond to the pathological condition.

Soluble HLA-DR antigen levels in serum correlate with rheumatoid arthritis disease activity and the presence of disease-associated epitopes

We investigated correlations between soluble HLA-DR (sHLA-DR) molecules and several clinical, biological and genetic parameters associated with rheumatoid arthritis (RA) disease activity. Serum sHLA-DR concentrations were determined in 146 samples from 89 RA patients by an ELISA format, using an antibody combination of mouse and rat monoclonal anti-human HLA-DR antibodies. The mean sHLA-DR serum level in RA patients was significantly increased with 277+/-19 ng/ml compared to 142+/-13 ng/ml of 80 healthy controls (P<0.001). In ascending order of significance, correlations were found between serum sHLA-DR and EULAR swelling and pain scores, Waaler-Rose, RA factor, ESR and CRP (P=0.025 to P<0.001). High sHLA-DR levels were defined above 374 ng/ml that was the 95% confidence interval of the controls. Thirty-seven blood samples (25%) in 31 RA patients were above this level. The EULAR pain and swelling scores, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and RA factor were higher (P=0.044 to P<0.001) at the moment of high sHLA-DR concentrations, compared to the lower concentrations. Higher disease activity was further found in groups of RA patients respectively heterozygous or homozygous for the disease-associated epitope (Q)R/KRAA within the HLA-DRB1 chain, compared to the group without this epitope (P<0.017 for part of the results). Likewise, sHLA-DR was respectively 169+/-17 (no disease associated epitope), 324+/-34 (heterozygous) and 442+/-69 ng/ml (homozygous for the disease-associated epitope on HLA-DRB1 alleles) (P<0.017). In conclusion, this study shows significant correlations between serum sHLA-DR levels and RA disease activity parameters, as well as increased sHLA-DR in patients with disease-associated epitope on HLA-DRB1 alleles.