Class I HLA folding and antigen presentation in beta 2-microglobulin-defective Daudi cells

Diversity in the HLA-I Recognition of HLA-F Monoclonal Antibodies: HLA-F or HLA-Ib Monospecific, HLA-E or HLA-G Bispecific Antibodies with or without HLA-Ia Reactivity

Previous investigators have used various anti-HLA-F monoclonal antibodies (mAbs) to demonstrate that the tissue distribution of HLA-F is highly restricted. Notably, these mAbs differed in their immunodiagnostic capabilities. Specifically, mAbs Fpep1.1 and FG1 detected HLA-F intracellularly in B cells but not on the cell surface, whereas mAb 3D11 detected HLA-F on the cell surface. The presence of HLA-F on T cells was recognized by mAb FG1 but not by mAb Fpep1.1. mAb 3D11 detected HLA-F on the cell surface of activated B cells and on peripheral blood lymphocytes, but not on the normal cells. Importantly, mAb 3D11 revealed that HLA-F exists as a heavy chain (HC) monomer, rather than as an HC associated with B2m. Although these mAbs are believed to be specific to HLA-F, their monospecificity has not been formally established, which is critical for immunodiagnostic and therapeutic purposes. Previously, we investigated the diversity of HLA class I reactivities of anti-HLA-E mAbs using HLA-I coated multiplex bead assays on a Luminex platform. We reported that more than 80% of the HLA-E mAbs were cross-reactive with other HLA-I molecules, with exceptionally few truly HLA-E-monospecific mAbs. In the present investigation, we generated IgG mAbs against HCs of HLA-F in Balb/C mice and examined the cross-reactivity of anti-HLA-F mAbs with other HLA-I alleles using a multiplex bead assay on the Luminex platform. Beads coated with an array of HLA homo- and heterodimers of different HLA-Ia (HLA-A, HLA-B, and HLA-C) and Ib (HLA-E, HLA-F, and HLA-G) alleles were used to examine the binding of the anti-HLA-F mAbs. Only two mAbs were HLA-F monospecific, and five were HLA-Ib restricted. Several anti-HLA-F mAbs cross-reacted with HLA-E (n = 4), HLA-G (n = 3), HLA-Ia alleles (n = 9), HLA-G and HLA-Ia (n = 2), and HLA-Ib and HLA-Ia (n = 6). This monospecificity and polyreactivity were corroborated by the presence of HLA-F monospecific and HLA-I-shared sequences. This study emphasizes the need to monitor the mono-specificity of HLA-F for reliable immunodiagnostics and passive immunotherapy.

Cell Surface B2m-Free Human Leukocyte Antigen (HLA) Monomers and Dimers: Are They Neo-HLA Class and Proto-HLA?

Cell surface HLA-I molecules (Face-1) consist of a polypeptide heavy chain (HC) with two groove domains (G domain) and one constant domain (C-domain) as well as a light chain, B2-microglobulin (B2m). However, HCs can also independently emerge unfolded on the cell surface without peptides as B2m-free HC monomers (Face-2), B2m-free HC homodimers (Face 3), and B2m-free HC heterodimers (Face-4). The transport of these HLA variants from ER to the cell surface was confirmed by antiviral antibiotics that arrest the release of newly synthesized proteins from the ER. Face-2 occurs at low levels on the normal cell surface of the lung, bronchi, epidermis, esophagus, breast, stomach, ilium, colorectum, gall bladder, urinary bladder, seminal vesicles ovarian epithelia, endometrium, thymus, spleen, and lymphocytes. They are upregulated on immune cells upon activation by proinflammatory cytokines, anti-CD3 antibodies, antibiotics (e.g., ionomycin), phytohemagglutinin, retinoic acid, and phorbol myristate acetate. Their density on the cell surface remains high as long as the cells remain in an activated state. After activation-induced upregulation, the Face-2 molecules undergo homo- and hetero-dimerization (Face-3 and Face-4). Alterations in the redox environment promote dimerization. Heterodimerization can occur among and between the alleles of different haplotypes. The glycosylation of these variants differ from that of Face-1, and they may occur with bound exogenous peptides. Spontaneous arthritis occurs in HLA-B27+ mice lacking B2m (HLA-B27+ B2m-/-) but not in HLA-B27+ B2m+/- mice. The mice with HLA-B27 in Face-2 spontaneous configuration develop symptoms such as changes in nails and joints, hair loss, and swelling in paws, leading to ankyloses. Anti-HC-specific mAbs delay disease development. Some HLA-I polyreactive mAbs (MEM series) used for immunostaining confirm the existence of B2m-free variants in several cancer cells. The upregulation of Face-2 in human cancers occurs concomitantly with the downregulation of intact HLAs (Face-1). The HLA monomeric and dimeric variants interact with inhibitory and activating ligands (e.g., KIR), growth factors, cytokines, and neurotransmitters. Similarities in the amino acid sequences of the HLA-I variants and HLA-II β-chain suggest that Face-2 could be the progenitor of both HLA classes. These findings may support the recognition of these variants as a neo-HLA class and proto-HLA.

Structural engineering of chimeric antigen receptors targeting HLA-restricted neoantigens

Chimeric antigen receptor (CAR) T cells have emerged as a promising class of therapeutic agents, generating remarkable responses in the clinic for a subset of human cancers. One major challenge precluding the wider implementation of CAR therapy is the paucity of tumor-specific antigens. Here, we describe the development of a CAR targeting the tumor-specific isocitrate dehydrogenase 2 (IDH2) with R140Q mutation presented on the cell surface in complex with a common human leukocyte antigen allele, HLA-B*07:02. Engineering of the hinge domain of the CAR, as well as crystal structure-guided optimization of the IDH2^R140Q-HLA-B*07:02-targeting moiety, enhances the sensitivity and specificity of CARs to enable targeting of this HLA-restricted neoantigen. This approach thus holds promise for the development and optimization of immunotherapies specific to other cancer driver mutations that are difficult to target by conventional means.

Chimeric antigen receptor T cells in the clinic currently target cell-type-specific extracellular antigens on malignant cells. Here, authors engineer tumor-specific chimeric antigen receptor T cells that target human leukocyte antigen-presented neoantigens derived from mutant intracellular proteins.

Targeting loss of heterozygosity for cancer-specific immunotherapy

Developing therapeutic agents with potent antitumor activity that spare normal tissues remains a significant challenge. Clonal loss of heterozygosity (LOH) is a widespread and irreversible genetic alteration that is exquisitely specific to cancer cells. We hypothesized that LOH events can be therapeutically targeted by "inverting" the loss of an allele in cancer cells into an activating signal. Here we describe a proof-of-concept approach utilizing engineered T cells approximating NOT-gate Boolean logic to target counterexpressed antigens resulting from LOH events in cancer. The NOT gate comprises a chimeric antigen receptor (CAR) targeting the allele of human leukocyte antigen (HLA) that is retained in the cancer cells and an inhibitory CAR (iCAR) targeting the HLA allele that is lost in the cancer cells. We demonstrate that engineered T cells incorporating such NOT-gate logic can be activated in a genetically predictable manner in vitro and in mice to kill relevant cancer cells. This therapeutic approach, termed NASCAR (Neoplasm-targeting Allele-Sensing CAR), could, in theory, be extended to LOH of other polymorphic genes that result in altered cell surface antigens in cancers.

Nomograms based on SUVmax of 18F-FDG PET/CT and clinical parameters for predicting progression-free and overall survival in patients with newly diagnosed extranodal natural killer/T-cell lymphoma

BACKGROUND

The prognostic value of 18F-FDG PET/CT in extranodal natural killer/T-cell lymphoma (ENKTL) is not well established. We aimed to develop nomograms for individualized estimates of progression-free survival (PFS) and overall survival (OS) in patients with ENKTL using 18F-FDG PET/CT parameters and clinical parameters.

METHODS

A total of 171 patients with newly diagnosed ENKTL undergoing 18F-FDG PET/CT scanning were retrospectively analyzed. Nomograms were constructed according to multivariate Cox proportional hazards regression. The predictive and discriminatory capacities of the nomograms were then measured using the concordance index (C-index), calibration plots, and Kaplan-Meier curves. The C-index, the area under receiver operating characteristic (ROC) curve (AUC), and decision curve analysis (DCA) were used to contrast the predictive and discriminatory capacities of the nomograms against with the International Prognostic Index (IPI) and Korean Prognostic Index (KPI).

RESULTS

Multivariate analysis demonstrated that pretreatment SUVmax≥9.5, disease stage II and III-IV, elevated lactate dehydrogenase (LDH), and elevated β2-microglobulin (β2-MG) had the strongest association with unfavorable PFS and OS. In addition, hemoglobin (Hb) < 120 g/L had a tendency to be associated with PFS. Both nomogram models incorporated SUVmax, Ann Arbor stage, LDH, and β2-MG. The PFS nomogram also included Hb. The nomograms showed good prediction accuracies, with the C-indexes for PFS and OS were 0.729 and 0.736, respectively. The calibration plots for 3-year and 5-year PFS/OS reported good consistency between predicted and observed probabilities for survival time. The PFS and OS were significantly different according to tertiles of nomogram scores (p < 0.001). The C-index and AUCs of the nomograms were higher than that of IPI and KPI. Moreover, DCA showed that the predictive accuracy of the nomograms for PFS and OS were both higher than that of IPI and KPI.

CONCLUSIONS

This study established nomograms that incorporate pretreatment SUVmax and clinical parameters, which could be effective tools for individualized prognostication of both PFS and OS in patients with newly diagnosed ENKTL.

Exhaustion of tumour-infiltrating T-cell receptor repertoire diversity is an age-dependent indicator of immunological fitness independently predictive of clinical outcome in Burkitt lymphoma

Burkitt lymphoma (BL) is an aggressive B-cell-malignancy derived from germinal-centre B-cells. Curative therapy traditionally requires intensive immunochemotherapy. Recently, immuno-oncological approaches, modulating the T-cell tumour response, were approved for the treatment of a variety of malignancies. The architecture of the tumour-infiltrating T-cell receptor (TCR) repertoire in BL remains insufficiently characterized. We therefore performed a large-scale, next-generation sequencing study of the complimentary-determining region (CDR)-3 region of the TCRβ chain repertoire in a large cohort of all epidemiological subtypes of BL (n = 82) and diffuse large B-cell lymphoma (DLBCL; n = 34). Molecular data were subsequently assessed for correlation with clinical outcome. Our investigations revealed an age-dependent immunoprofile in BL as in DLBCL. Moreover, we found several public clonotypes in numerous patients suggestive of shared tumour neoantigen selection exclusive to BL and distinct from DLBCL regardless of Epstein-Barr virus and/or human immunodeficiency virus status. Compared with baseline, longitudinal analysis unveiled significant repertoire restrictions upon relapse (P = 0·0437) while productive TCR repertoire clonality proved to be a useful indicator of both overall and progression-free-survival [OS: P = 0·0001; hazard ratio (HR): 6·220; confidence interval (CI): 2·263-11·78; PFS: P = 0·0025; HR: 3·086; CI: 1·555-7·030]. Multivariate analysis confirmed its independence from established prognosticators, including age at diagnosis and comorbidities. Our findings establish the clinical relevance of the architecture and clonality of the TCR repertoire and its age-determined dynamics in BL.

Adenosine-Induced NLRP11 in B Lymphoblasts Suppresses Human CD4+ T Helper Cell Responses

NLRP11 is a member of the PYD domain-containing, nucleotide-binding oligomerization-domain (NOD-) like receptor (NLR) family. The true stimulus of NLRP11 is still unclear to date, so the current study is built upon NLRP11 induction via adenosine stimulation and that activation can shape adaptive immune responses in a caspase-1-independent manner. We examined the regulation and mechanism of adenosine responsiveness via NLRP11 in human Daudi Burkitt's B lymphoma cells and their effects on human peripheral CD4⁺ T lymphocytes from healthy individuals. NLRP11 was significantly upregulated after induction with adenosine at both the mRNA and protein levels, which led to the interaction of endogenous NLRP11 with the ASC adaptor protein; however, this interaction did not result in the activation of the caspase-1 enzyme. Furthermore, cocultures of NLRP11-expressing Burkitt's lymphoma cells and naïve human peripheral CD4⁺ T lymphocytes had reduced IFN-γ and IL-17A production, whereas IL-13 and IL-10 cytokines did not change. Interestingly, IFN-γ and IL-17A were recovered after transfection of Burkitt's lymphoma cells with siRNAs targeting NLRP11. Concomitant with NLRP11 upregulation, we also exhibited that adenosine A_2B receptor signaling induced two phosphorylated downstream effectors, pErk1/2 and pAkt (Ser473), but not pAkt (Thr308). Taken together, our data indicate that adenosine is a negative regulator of Th1 and Th17 responses via NLRP11 in an inflammasome-independent manner.

Endocytic Recycling of MHC Class I Molecules in Non-professional Antigen Presenting and Dendritic Cells

Major histocompatibility complex class I (MHC I) molecules are glycoproteins that display peptide epitopes at the cell surface of nucleated cells for recognition by CD8⁺ T cells. Like other cell surface receptors, MHC class I molecules are continuously removed from the surface followed by intracellular degradation or recycling to the cell surface, in a process likely involving active quality control the mechanism of which remains unknown. The molecular players and pathways involved in internalization and recycling have previously been studied in model cell lines such as HeLa. However, dendritic cells (DCs), which rely on a specialized endocytic machinery that confers them the unique ability to “cross”-present antigens acquired by internalization, may use distinct MHC I recycling pathways and quality control mechanisms. By providing MHC I molecules cross-presenting antigens, these pathways may play an important role in one of the key functions of DCs, priming of T cell responses against pathogens and tumors. In this review, we will focus on endocytic recycling of MHC I molecules in various experimental conditions and cell types. We discuss the organization of the recycling pathway in model cell lines compared to DCs, highlighting the differences in the recycling rates and pathways of MHC I molecules between various cell types, and their putative functional consequences. Reviewing the literature, we find that conclusive evidence for significant recycling of MHC I molecules in primary DCs has yet to be demonstrated. We conclude that endocytic trafficking of MHC class I in DCs remains poorly understood and should be further studied because of its likely role in antigen cross-presentation.

Monitoring native HLA-I trimer specific antibodies in Luminex multiplex single antigen bead assay: Evaluation of beadsets from different manufacturers

Luminex single antigen bead (SAB) assay utilizes beadsets coated with a set of cloned and purified HLA molecules, for monitoring serum anti-HLA antibodies. Particularly, the level of serum IgG against native HLA-I trimers (heavy chain (HC) and β2-microglobulin (β2m) with a peptide), expressed in allograft tissues is correlated with graft failure. In addition to native trimeric HLAI, the beadsets may carry HC only or the dimeric variants, peptide-free HC with β2m and β2m-free HC with or without peptides. Currently, three different HLA-I coated beadsets have been produced commercially. The HLA antigen density on one beadset was reported to be approximately 50% of that present on another beadset as evidenced by the binding of an anti-HLA-I mAb W6/32. To date, no efforts have been made to compare the relative distribution of HLA-I variants in these three beadsets. In this study, using monoclonal antibodies (W6/32, HC-10 and TFL-006) that can distinguish the structural variants based on their epitope specificities, the nature of the variants in the three beadsets were comparatively evaluated. One beadset (Beadset A, see Materials and methods for Brand and Manufacturer's names) (W6/32+/HC-10+/TFL-006+) carried at least three variants, while beadset B (W6/32+/HC-10+/TFL-006-) carried two (peptide-associated and peptide-free β2m-HC) and the beadset C (W6/32+/HC-10-/TFL-006-) carried exclusively the HLA-I trimer suggesting its usefulness for specific monitoring native HLA-I trimer antibodies. Because of the salient differences in the variants coated on the different beadsets, it would be warranted to investigate, if these differences are clinically relevant for monitoring serum anti-HLA antibodies in sensitized patients waiting for donor organs and in allograft recipients (274).

Technical Limitations of the C1q Single-Antigen Bead Assay to Detect Complement Binding HLA-Specific Antibodies

BACKGROUND

Solid-phase assays to distinguish complement binding from noncomplement binding HLA-specific antibodies have been introduced, but technical limitations may compromise their interpretation. We have examined the extent to which C1q-binding to HLA-class I single-antigen beads (SAB) is influenced by denatured HLA on SAB, antibody titre, and complement interference that causes a misleading low assessment of HLA-specific antibody levels.

METHODS

Sera from 25 highly sensitized patients were tested using Luminex IgG-SAB and C1q-SAB assays. Sera were tested undiluted, at 1:20 dilution to detect high-level IgG, and after ethylene diamine tetraacetic acid treatment to obviate complement interference. Conformational HLA and denatured HLA protein levels on SAB were determined using W6/32 and HC-10 monoclonal antibodies, respectively. Denatured HLA was expressed as HC-10 binding to untreated SAB as a percentage of maximal binding to acid-treated SAB.

RESULTS

For undiluted sera, Luminex mean fluorescence intensity (MFI) values for IgG-SAB and C1q-SAB correlated poorly (r = 0.42). ethylene diamine tetraacetic acid and serum dilution improved the correlation (r = 0.57 and 0.77, respectively). Increasing levels of denatured HLA interfered with the detection of C1q binding. Consequently, the correlation between IgG-SAB MFI and C1q-SAB MFI was lowest using undiluted sera and SAB with greater than 30% denatured HLA (r = 0.40) and highest using diluted sera and SAB with 30% or less denatured HLA (r = 0.86).

CONCLUSIONS

Antibody level, complement interference, and denatured HLA class I on SAB may all affect the clinical interpretation of the C1q-SAB assay. The C1q-SAB assay represents a substantial additional cost for routine clinical use, and we question its justification given the potential uncertainty about its interpretation.

Adenovirus expressing β2-microglobulin recovers HLA class I expression and antitumor immunity by increasing T-cell recognition

Optimal tumor cell surface expression of human leukocyte antigen (HLA) class I molecules is essential for the presentation of tumor-associated peptides to T-lymphocytes. However, a hallmark of many types of tumor is the loss or downregulation of HLA class I expression associated with ineffective tumor antigen presentation to T cells. Frequently, HLA loss can be caused by structural alterations in genes coding for HLA class I complex, including the light chain of the complex, β2-microglobulin (β2m). Its best-characterized function is to interact with HLA heavy chain and stabilize the complex leading to a formation of antigen-binding cleft recognized by T-cell receptor on CD8+ T cells. Our previous study demonstrated that alterations in the β2m gene are frequently associated with cancer immune escape leading to metastatic progression and resistance to immunotherapy. These types of defects require genetic transfer strategies to recover normal expression of HLA genes. Here we characterize a replication-deficient adenoviral vector carrying human β2m gene, which is efficient in recovering proper tumor cell surface HLA class I expression in β2m-negative tumor cells without compromising the antigen presentation machinery. Tumor cells transduced with β2m induced strong activation of T cells in a peptide-specific HLA-restricted manner. Gene therapy using recombinant adenoviral vectors encoding HLA genes increases tumor antigen presentation and represents a powerful tool for modulation of tumor cell immunogenicity by restoration of missing or altered HLA genes. It should be considered as part of cancer treatment in combination with immunotherapy.

The biochemistry and immunology of non-canonical forms of HLA-B27

HLA-B27 (B27) is strongly associated with the spondyloarthritides. B27 is expressed at the cell surface of antigen presenting cells (APC) both as canonical β2m-associated and non-canonical β2m-free heavy chain (FHC) forms which include B27 dimers (termed B272). B27 FHC forms arise in an endosomal compartment from recycling β2m-associated B27. Formation of cell surface FHC dimers is critically dependent on an unpaired reactive cysteine 67 in the α1 helix of the class I heavy chain. HLA-B27 also form redox-inducible β2m-associated dimers on exosomes and apoptosing cells. By contrast with cell surface expressed cysteine 67-dependent heavy chain dimers these dimers are dependent on a cytoplasmic cysteine 325 for their formation. HLA-B27 binds to immunoregulatory receptors including members of the Killer cell Immunoglobulin-like (KIR) and Leukocyte Immunoglobulin-like receptor family. B27 FHC bind to different but overlapping sets of these immunoreceptors compared to classical β2m-associated HLA-B27. B27 FHC bind more strongly to KIR3DL2 and LILRB2 immune receptor than other β2m-associated HLA-class I ligands. Genetic studies have implicated genes which control production of the important proinflammatory cytokine IL-17 in the pathogenesis of spondyloarthritis. Cell surface HLA-B27 FHC binding to these immune receptors or acting through other mechanisms could impact on the pathogenesis of spondyloarthritis by promoting immune cell production of IL-17. Here we review the literature on these non-canonical forms of HLA-B27 and the immune receptors they bind to and discuss the possible relevance of these interactions to the pathogenesis of spondyloarthropathy.

The arthritis-associated HLA-B*27:05 allele forms more cell surface B27 dimer and free heavy chain ligands for KIR3DL2 than HLA-B*27:09

Objectives. HLA-B*27:05 is associated with AS whereas HLA-B*27:09 is not associated. We hypothesized that different interactions with KIR immune receptors could contribute to the difference in disease association between HLA-B*27:05 and HLAB*27:09. Thus, the objective of this study was to compare the formation of β2m-free heavy chain (FHC) including B27 dimers (B272) by HLA-B*27:05 and HLA-B*27:09 and their binding to KIR immunoreceptors.

Methods. We studied the formation of HLA-B*27:05 and HLA-B*27:09 heterotrimers and FHC forms including dimers in vitro and in transfected cells. We investigated HLA-B*27:05 and HLA-B*27:09 binding to KIR3DL1, KIR3DL2 and LILRB2 by FACS staining with class I tetramers and by quantifying interactions with KIR3DL2CD3ε-reporter cells and KIR3DL2-expressing NK cells. We also measured KIR expression on peripheral blood NK and CD4 T cells from 18 HLA-B*27:05 AS patients, 8 HLA-B27 negative and 12 HLA-B*27:05+ and HLA-B*27:09+ healthy controls by FACS staining.

Results. HLA-B*27:09 formed less B27₂ and FHC than HLA-B*27:05. HLA-B*27:05-expressing cells stimulated KIR3DL2CD3ε-reporter T cells more effectively. Cells expressing HLA-B*27:05 promoted KIR3DL2+ NK cell survival more strongly than HLA-B*27:09. HLA-B*27:05 and HLA-B*27:09 dimer tetramers stained KIR3DL1, KIR3DL2 and LILRB2 equivalently. Increased proportions of NK and CD4 T cells expressed KIR3DL2 in HLA-B*27:05+ AS patients compared with HLA-B*27:05+, HLA-B*27:09+ and HLA-B27− healthy controls.

Conclusion. Differences in the formation of FHC ligands for KIR3DL2 by HLA-B*27:05 and HLA-B*27:09 could contribute to the differential association of these alleles with AS.

KIR3DL2 binds to HLA-B27 dimers and free H chains more strongly than other HLA class I and promotes the expansion of T cells in ankylosing spondylitis

The human leukocyte Ag HLA-B27 (B27) is strongly associated with the spondyloarthritides. B27 can be expressed at the cell surface of APC as both classical β2-microglobulin-associated B27 and B27 free H chain forms (FHC), including disulfide-bonded H chain homodimers (termed B27(2)). B27 FHC forms, but not classical B27, bind to KIR3DL2. HLA-A3, which is not associated with spondyloarthritis (SpA), is also a ligand for KIR3DL2. In this study, we show that B27(2) and B27 FHC bind more strongly to KIR3DL2 than other HLA-class I, including HLA-A3. B27(2) tetramers bound KIR3DL2-transfected cells more strongly than HLA-A3. KIR3DL2Fc bound to HLA-B27-transfected cells more strongly than to cells transfected with other HLA-class I. KIR3DL2Fc pulled down multimeric, dimeric, and monomeric FHC from HLA-B27-expressing cell lines. Binding to B27(2) and B27 FHC stimulated greater KIR3DL2 phosphorylation than HLA-A3. B27(2) and B27 FHC stimulated KIR3DL2CD3ε-transduced T cell IL-2 production to a greater extent than control HLA-class I. KIR3DL2 binding to B27 inhibited NK IFN-γ secretion and promoted greater survival of KIR3DL2(+) CD4 T and NK cells than binding to other HLA-class I. KIR3DL2(+) T cells from B27(+) SpA patients proliferated more in response to Ag presented by syngeneic APC than the same T cell subset from healthy and disease controls. Our results suggest that expansion of KIR3DL2-expressing leukocytes observed in B27(+) SpA may be explained by the stronger interaction of KIR3DL2 with B27 FHC.

Serum beta2-microglobin is a predictor of prognosis in patients with upper aerodigestive tract NK/T-cell lymphoma

Upper aerodigestive tract natural killer (NK)/T-cell lymphoma (UNKTL) is the most common type of extranodal NK/T-cell lymphoma, nasal type. Serum beta2-microglobulin (β2-M) was found to be a predictor in some subtypes of B-cell lymphoma. However, its prognostic significance in NK/T-cell lymphoma has never been explored. We retrospectively analyzed 82 patients newly diagnosed as UNKTL. Serum β2-M was detected prior to treatment in this series. Various statistical analyses were performed to evaluate the significance of the relevant clinical parameters. High serum β2-M level was calculated as ≥2.5 mg/L by the median value. The number of patients with serum β2-M ≥2.5 mg/L at diagnosis was 39 (47.6%) and 43 patients (52.4%) with β2-M <2.5 mg/L. Patients with high serum β2-M level at diagnosis seemed to have more adverse clinical features: B symptoms (p=0.007) and elevated LDH level (p<0.001), and high KPI score (p=0.002). Serum β2-M ≥2.5 mg/L was significantly associated with poor overall survival (5-year OS, 35.2% vs 73.6%; p=0.001) and progression-free survival (5-year PFS, 27.5% vs 55.9%; p=0.028). For patients with early stage, serum β2-M at diagnosis could also help to distinguish those with favorable outcomes from those with poor outcomes. In multivariate analysis, high serum β2-M level remained its prognostic impact on survival (OS: p=0.002; PFS: p=0.039), independent of the International Prognostic Index score. Our study suggested high serum β2-M was a novel predictor of prognosis in patients with UNKTL. A simply and regular way might be established to identify UNKTL patients of different risks at diagnosis.

Towards a systems understanding of MHC class I and MHC class II antigen presentation

The molecular details of antigen processing and presentation by MHC class I and class II molecules have been studied extensively for almost three decades. Although the basic principles of these processes were laid out approximately 10 years ago, the recent years have revealed many details and provided new insights into their control and specificity. MHC molecules use various biochemical reactions to achieve successful presentation of antigenic fragments to the immune system. Here we present a timely evaluation of the biology of antigen presentation and a survey of issues that are considered unresolved. The continuing flow of new details into our understanding of the biology of MHC class I and class II antigen presentation builds a system involving several cell biological processes, which is discussed in this Review.

Towards a systems understanding of MHC class I and MHC class II antigen presentation

The molecular details of antigen processing and presentation by MHC class I and class II molecules have been studied extensively for almost three decades. Although the basic principles of these processes were laid out approximately 10 years ago, the recent years have revealed many details and provided new insights into their control and specificity. MHC molecules use various biochemical reactions to achieve successful presentation of antigenic fragments to the immune system. Here we present a timely evaluation of the biology of antigen presentation and a survey of issues that are considered unresolved. The continuing flow of new details into our understanding of the biology of MHC class I and class II antigen presentation builds a system involving several cell biological processes, which is discussed in this Review.