scholarly journals A Micropolymorphism Altering the Residue Triad 97/114/156 Determines the Relative Levels of Tapasin Independence and Distinct Peptide Profiles for HLA-A*24 Allotypes

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Soumya Badrinath ◽  
Heike Kunze-Schumacher ◽  
Rainer Blasczyk ◽  
Trevor Huyton ◽  
Christina Bade-Doeding
Keyword(s):  
Significant Risk ◽  
Hla Class I ◽  
Surface Expression ◽  
Class I ◽  
Cell Surface Expression ◽  
Hematopoietic Stem ◽  
Hla Class I Molecules ◽  
Peptide Loading ◽  
Peptide Profiles ◽  
Distinct Peptide

While many HLA class I molecules interact directly with the peptide loading complex (PLC) for conventional loading of peptides certain class I molecules are able to present peptides in a way that circumvents the PLC components. We investigated micropolymorphisms at position 156 of HLA-A*24 allotypes and their effects on PLC dependence for assembly and peptide binding specificities. HLA-A*24:06156Trpand HLA-A*24:13156Leushowed high levels of cell surface expression while HLA-A*24:02156Glnwas expressed at low levels in tapasin deficient cells. Peptides presented by these allelic variants showed distinct differences in features and repertoire. Immunoprecipitation experiments demonstrated all the HLA-A*24/156 variants to associate at similar levels with tapasin when present. Structurally, HLA-A*24:02 contains the residue triad Met97/His114/Gln156 and a Trp156 or Leu156 polymorphism provides tapasin independence by stabilizing these triad residues, thus generating an energetically stable and a more peptide receptive environment. Micropolymorphisms at position 156 can influence the generic peptide loading pathway for HLA-A*24 by altering their tapasin dependence for peptide selection. The trade-off for this tapasin independence could be the presentation of unusual ligands by these alleles, imposing significant risk following hematopoietic stem cell transplantation (HSCT).

scholarly journals Variations in HLA-B cell surface expression, half-life and extracellular antigen receptivity

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Brogan Yarzabek ◽  
Anita J Zaitouna ◽  
Eli Olson ◽  
Gayathri N Silva ◽  
Jie Geng ◽  
...  
Keyword(s):  
Cell Surface ◽  
Half Life ◽  
Antigen Processing ◽  
Human Lymphocytes ◽  
Hla Class I ◽  
Surface Expression ◽  
Class I ◽  
Cell Surface Expression ◽  
Specific Expression ◽  
Hla Class I Molecules

The highly polymorphic human leukocyte antigen (HLA) class I molecules present peptide antigens to CD8+ T cells, inducing immunity against infections and cancers. Quality control mediated by peptide loading complex (PLC) components is expected to ensure the cell surface expression of stable peptide-HLA class I complexes. This is exemplified by HLA-B*08:01 in primary human lymphocytes, with both expression level and half-life at the high end of the measured HLA-B expression and stability hierarchies. Conversely, low expression on lymphocytes is measured for three HLA-B allotypes that bind peptides with proline at position 2, which are disfavored by the transporter associated with antigen processing. Surprisingly, these lymphocyte-specific expression and stability differences become reversed or altered in monocytes, which display larger intracellular pools of HLA class I than lymphocytes. Together, the findings indicate that allele and cell-dependent variations in antigen acquisition pathways influence HLA-B surface expression levels, half-lives and receptivity to exogenous antigens.

Analysis of natural killer cells in TAP2-deficient patients: expression of functional triggering receptors and evidence for the existence of inhibitory receptor(s) that prevent lysis of normal autologous cells

Blood ◽  
2002 ◽  
Vol 99 (5) ◽  
pp. 1723-1729 ◽  
Author(s):  
Massimo Vitale ◽  
Jacques Zimmer ◽  
Roberta Castriconi ◽  
Daniel Hanau ◽  
Lionel Donato ◽  
...  
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Antigen Processing ◽  
Nk Cell ◽  
Hla Class I ◽  
Surface Expression ◽  
Class I ◽  
Inhibitory Receptor ◽  
Surface Receptors ◽  
Hla Class I Molecules

Natural killer (NK) cells are characterized by the ability to kill cells that lack HLA class I molecules while sparing autologous normal (HLA class I+) cells. However, patients with transporter-associated antigen processing (TAP) deficiency, though displaying strong reductions of HLA class I surface expression, in most instances do not experience NK-mediated autoimmune phenomena. A possible mechanism by which TAP−/− NK cells avoid autoreactivity against autologous HLA class I–deficient cells could be based on either quantitative or qualitative defects of surface receptors involved in NK cell triggering. In this study we show that NK cells derived from 2 patients with TAP2−/− express normal levels of all known triggering receptors. As revealed by the analysis of polyclonal and clonal NK cells, these receptors display normal functional capabilities and allow the killing of a panel of NK-susceptible targets, including autologous B-LCLs. On the other hand, TAP2−/− NK cells were unable to kill either allogeneic (HLA class I+) or autologous (HLA class I− ) phytohemagglutinin (PHA) blasts even in the presence of anti-HLA class I monoclonal antibody. These data suggest that TAP2−/− NK cells express still unknown inhibitory receptor(s) capable of down-regulating the NK cell cytotoxicity on binding to surface ligand(s) expressed by T cell blasts. Functional analyses, both at the polyclonal and at the clonal level, are consistent with the concept that the putative inhibitory receptor is expressed by virtually all TAP2−/− NK cells, whereas it is present only in rare NK cells from healthy persons. Another possibility would be that TAP2−/− NK cells are missing a still unidentified triggering receptor involved in NK cell-mediated killing of PHA blasts.

scholarly journals Role of Interferon-Stimulated Gene Factor 3γ and Beta Interferon in HLA Class I Enhancement in Synovial Fibroblasts upon Infection with Chlamydia trachomatis

2002 ◽  
Vol 70 (11) ◽  
pp. 6140-6146 ◽  
Author(s):  
Jürgen Rödel ◽  
Heinz Vogelsang ◽  
Katrin Prager ◽  
Matthias Hartmann ◽  
Karl-Hermann Schmidt ◽  
...  
Keyword(s):  
Chlamydia Trachomatis ◽  
Flow Cytometric Analysis ◽  
Hla Class I ◽  
Synovial Fibroblasts ◽  
Host Cells ◽  
Class I ◽  
Cell Surface Expression ◽  
Beta Interferon ◽  
Enhanced Production ◽  
Hla Class I Molecules

ABSTRACT Chlamydia trachomatis infection can cause reactive arthritis that is associated with the persistence of chlamydial organisms in the joint. Fibroblasts of the synovial membrane represent host cells for Chlamydia during articular infection. In this study we investigated the expression of HLA class I molecules in synovial fibroblasts following infection with C. trachomatis D. The expression of HLA class I heavy chain (HLA-I) was up-regulated in infected cultures as shown by reverse transcription-PCR and immunoblotting. The increase in cell surface expression of HLA-I and β2 microglobulin on infected fibroblasts was demonstrated by flow cytometric analysis. Suppression of enhanced production of interferon-stimulated gene factor 3γ (ISGF3γ) in infected cell cultures by antisense oligonucleotide treatment reduced the level of HLA-I. Blocking antibodies to beta interferon (IFN-β) inhibited the Chlamydia-induced enhancement of both ISGF3γ and HLA-I. These findings show that the up-regulation of HLA-I in synovial fibroblasts infected with C. trachomatis is caused by the induction of IFN-β, which in turn stimulates the synthesis of ISGF3γ, a transcription factor participating in the regulation of the HLA-I gene. The IFN-β-mediated expression of HLA-I on Chlamydia-infected cells may be a regulatory factor in the immune response in chlamydial infections.

Association of a syndrome resembling Wegener's granulomatosis with low surface expression of HLA class-I molecules

The Lancet ◽  
1999 ◽  
Vol 354 (9190) ◽  
pp. 1598-1603 ◽  
Author(s):  
Hélène T Moins-Teisserenc ◽  
Stephan D Gadola ◽  
Marina Cella ◽  
P Rod Dunbar ◽  
Andrew Exley ◽  
...  
Keyword(s):  
Wegener’S Granulomatosis ◽  
Hla Class I ◽  
Surface Expression ◽  
Wegener's Granulomatosis ◽  
Class I ◽  
Hla Class I Molecules

scholarly journals Anchoring pockets in human histocompatibility complex leukocyte antigen (HLA) class I molecules: analysis of the conserved B ("45") pocket of HLA-B27.

1992 ◽  
Vol 175 (3) ◽  
pp. 809-820 ◽  
Author(s):  
S E Buxton ◽  
R J Benjamin ◽  
C Clayberger ◽  
P Parham ◽  
A M Krensky
Keyword(s):  
Critical Role ◽  
Peptide Binding ◽  
Hla Class I ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Amino Acid Side Chain ◽  
Hla B27 ◽  
Leukocyte Antigen ◽  
Functional Studies ◽  
Hla Class I Molecules

Dissection of the peptide binding grooves of seven subtypes of human histocompatibility leukocyte antigen (HLA)-B27 into the six specificity pockets defined by the 2.6-A structure of HLA-A*0201 revealed just one pocket, the B ("45") pocket, that is conserved among all the HLA-B27 subtypes. Functional studies of mutant HLA-B*2705 molecules with point substitutions in residues of the B pocket show that this structure, and the glutamine residue at position 45 in particular, plays a critical role in cell surface expression, peptide binding, and in the presentation of both exogenous and endogenous peptides by HLA-B*2705. We predict that the B pocket of HLA-B*2705 interacts with an amino acid side chain that anchors peptides in the binding groove, and that this peptide motif is present in most endogenously processed peptides that bind to all seven subtypes of HLA-B27.

scholarly journals Spectrum and Clinical Significance of HLA Class I Alleles and Their Somatic Mutations in Immune Aplastic Anemia

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3738-3738
Author(s):  
Yoshitaka Zaimoku ◽  
Sharon D. Adams ◽  
Bhavisha A Patel ◽  
Audrey Ai Chin Lee ◽  
Sachiko Kajigaya ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Surface ◽  
Aplastic Anemia ◽  
Clinical Significance ◽  
Somatic Mutations ◽  
Clonal Evolution ◽  
Hla Class I ◽  
Surface Expression ◽  
Class I ◽  
Cell Surface Expression

Clonal hematopoiesis associated with loss of HLA class I alleles due to somatic mutations and/or 6p loss of heterozygosity (LOH) is frequent in immune aplastic anemia (AA). HLA-B*40:02 is more likely to be involved in HLA loss in Japanese AA patients, suggesting a role for this allele in immune pathophysiology (Zaimoku Y et al, Blood 2017). Mutations in non-B*40:02 HLA class I alleles have been reported in a limited number of patients from the United States (Babushok D et al, Blood Adv 2017) and Japan (Mizumaki H et al, 60th ASH meeting), but their prevalence and clinical significance are not well characterized. We investigated somatic mutations of HLA class I alleles, HLA allele frequencies, and their correlations with outcomes of therapy in a total of 532 AA patients, aged 2 years or older, treated on various Hematology Branch protocols (clinicaltrials.gov NCTs 00001964, 00061360, 00195624, 00260689, 00944749, 01193283, and 01623167). HLA allele-lacking (HLA-) monocytes from cryopreserved peripheral blood mononuclear cells were screened by flow cytometry after staining with allele-specific monoclonal antibodies for HLA-A and/or HLA-B (HLA-flow) in 172 AA patients. HLA- monocytes accounting for 0.5% to 100% (median 9.5%) of total monocytes were detected in 49 (28%) of the 172 patients and in 59 (15%) of 382 alleles analyzed (Figure 1). Loss of cell surface expression was frequent for HLA-B14 (46%), B27 (33%), B49 (33%), A68 (26%), A2 (23%), B40 (21%), and B8 (21%). One percent to 60% (median, 8.9%) of glycosylphosphatidylinositol-linked protein-negative (GPI-) monocytes were also present in 43% (21 of 49) of the patients with HLA- monocytes, but GPI- clones had normal HLA cell surface expression. Deep sequencing of HLA-A, HLA-B and HLA-C on sorted HLA- and HLA+GPI+ monocytes was performed in 42 of the 48 patients from whom adequate cells were available. Somatic mutations and/or LOH corresponding to the lacking alleles were detected in all 42 cases (Figure 1): 9 had both somatic mutations and LOH, 20 had somatic mutations only, and 13 had LOH only. Among the 13 patients who showed only LOH in the absent allele, 6 had somatic mutations in other alleles of HLA+ monocytes that was not analyzable of HLA expression, and 2 had a breakpoint of LOH between HLA-A and HLA-C, leading to loss of a single HLA-A allele. Somatic mutations or LOH involving only one allele were present in 37 patients among 6 HLA-A alleles (in 02:01 [7 patients], 02:05 [1], 02:06 [3], 02:11 [1], 68:01 [2], 68:02 [2]) and 10 HLA-B alleles (07:02 [1], 08:01 [4], 14:01 [1], 14:02 [7], 27:05 [1], 35:02 [1], 35:05 [1], 40:01 [1], 40:02 [3], 45:01 [1]), but were not found in HLA-C alleles. HLA allele frequencies in AA patients, including 271 white Americans, 120 African-Americans, and 99 Hispanics and Latinos, were compared with ethnicity-matched individuals in bone marrow donor datasets of the National Marrow Donor Program, and underwent random-effects meta-analyses. HLA-B*07, B*14, and B*40 were overrepresented in AA, while A*02, A*68, and B*08 frequencies were similar to those of healthy donors (Figure 2). In 164 severe AA patients who were initially treated with horse antithymocyte globulin (hATG), cyclosporine, and eltrombopag between 2012 and 2018, 36 and 79 were positive and negative for HLA- monocytes, respectively, and 49 were not tested by HLA-flow. There was no significant difference in overall and complete response rates at six months among the three groups (Figure 3). Clonal evolution, defined as acquisition of abnormal bone marrow cytogenetics or morphology, especially high-risk evolution to chromosome 7 abnormalities, complex cytogenetics, or morphological MDS/AML, tended to be more frequent in patients with HLA- monocytes, compared to the other two groups, but the difference did not reach statistical significance. Clinical outcomes were also assessed according to the presence of specific HLA alleles in 400 severe AA patients who were treated with hATG-based initial immunosuppressive therapy from 2000 to 2018: there was no significant differences in probabilities of response and clonal evolution according to the alleles associated with somatic mutations. Our study revealed that somatic mutations in HLA genes in AA are broadly distributed, but some alleles are preferentially affected. Inconsistent with previous studies, we found that outcomes of therapy did not significantly correlate with HLA gene mutations or with distinct HLA alleles. Disclosures No relevant conflicts of interest to declare.

scholarly journals Impaired intracellular transport and cell surface expression of nonpolymorphic HLA-E: evidence for inefficient peptide binding.

1992 ◽  
Vol 176 (4) ◽  
pp. 1083-1090 ◽  
Author(s):  
M Ulbrecht ◽  
J Kellermann ◽  
J P Johnson ◽  
E H Weiss
Keyword(s):  
Cell Surface ◽  
Intracellular Transport ◽  
Hla Class I ◽  
Surface Expression ◽  
Myeloma Cell ◽  
Peptide Ligands ◽  
Class I ◽  
Cell Surface Expression ◽  
Trimolecular Complex ◽  
Beta 2 Microglobulin

The assembly of the classical, polymorphic major histocompatibility complex class I molecules in the endoplasmic reticulum requires the presence of peptide ligands and beta 2-microglobulin (beta 2m). Formation of this trimolecular complex is a prerequisite for efficient transport to the cell surface, where presented peptides are scanned by T lymphocytes. The function of the other class I molecules is in dispute. The human, nonclassical class I gene, HLA-E, was found to be ubiquitously transcribed, whereas cell surface expression was difficult to detect upon transfection. Pulse chase experiments revealed that the HLA-E heavy chain in transfectants, obtained with the murine myeloma cell line P3X63-Ag8.653 (X63), displays a significant reduction in oligosaccharide maturation and intracellular transport compared with HLA-B27 in corresponding transfectants. The accordingly low HLA-E cell surface expression could be significantly enhanced by either reducing the culture temperature or by supplementing the medium with human beta 2m, suggesting inefficient binding of endogenous peptides to HLA-E. To analyze whether HLA-E binds peptides and to identify the corresponding ligands, fractions of acid-extracted material from HLA-E/X63 transfectants were separated by reverse phase HPLC and were tested for their ability to enhance HLA-E cell surface expression. Two fractions specifically increased the HLA class I expression on the HLA-E transfectant clone.

Sign in / Sign up

Export Citation Format

Share Document