High frequency of HLA B62 in fulminant type 1 diabetes with the drug-induced hypersensitivity syndrome

CONTEXT

Fulminant type 1 diabetes (FT1D) is a subtype of type 1 diabetes characterized by an extremely abrupt onset. FT1D cases associated with the drug-induced hypersensitivity syndrome (DIHS) have recently been reported.

OBJECTIVE

The clinical characteristics of FT1D associated with DIHS were investigated in this study.

METHODS

Case reports of FT1D associated with DIHS in Japanese subjects were collected and analyzed by means of a questionnaire to the authors. A nationwide questionnaire survey was administered to dermatology specialists, concerning the frequency of FT1D associated with DIHS.

RESULTS

In 15 case reports, the mean age at onset of FT1D was 53.4 yr and the mean time for its development from the onset of DIHS was 39.9 d. A higher frequency of human leukocyte antigen (HLA) B62, but not of HLA DR was found in FT1D with DIHS than that for cases without DIHS (P < 0.001). The reactivation of herpes virus 6 and cytomegalovirus was detected in 11 and four cases, respectively. Among 746 patients with DIHS in the nationwide survey, four developed FT1D during a 3-yr period. The frequency of FT1D in DIHS (0.54%) was much higher than that in the general Japanese population (0.010%).

CONCLUSIONS

The clinical characteristics of FT1D with DIHS were similar to those without DIHS except for the high frequency of HLA B62, which may be involved in the pathogenesis of FT1D with DIHS. Because the frequency was much higher than that in the general Japanese population, FT1D should be kept in mind when DIHS develops.

HLA-B*2704, an Allotype Associated with Ankylosing Spondylitis, Is Critically Dependent on Transporter Associated with Antigen Processing and Relatively Independent of Tapasin and Immunoproteasome for Maturation, Surface Expression, and T Cell Recognition: Relationship to B*2705 and B*2706

B*2704 is strongly associated to ankylosing spondylitis in Asian populations. It differs from the main HLA-B27 allotype, B*2705, in three amino acid changes. We analyzed the influence of tapasin, TAP, and immunoproteasome induction on maturation, surface expression, and T cell allorecognition of B*2704 and compared some of these features with B*2705 and B*2706, allotypes not associated to disease. In the tapasin-deficient .220 cell line, this chaperone significantly influenced the extent of folding of B*2704 and B*2705, but not their egress from the endoplasmic reticulum. In contrast, B*2706 showed faster folding and no accumulation in the endoplasmic reticulum in the absence of tapasin. Surface expression of B*2704 was more tapasin dependent than B*2705. However, expression of free H chain decreased in the presence of this chaperone for B*2705 but not B*2704, suggesting that more suboptimal ligands were loaded on B*2705 in the absence of tapasin. Despite its influence on surface expression, tapasin had little effect on allorecognition of B*2704. Both surface expression and T cell recognition of B*2704 were critically dependent on TAP, as established with TAP-deficient and TAP-proficient T2 cells. Both immunoproteasome and surface levels of B*2704 were induced by IFN-gamma, but this had little effect on allorecognition. Thus, except for the differential effects of tapasin on surface expression, the tapasin, TAP, and immunoproteasome dependency of B*2704 for maturation, surface expression, and T cell recognition are similar to B*2705, indicating that basic immunological features are shared by the two major HLA-B27 allotypes associated to ankylosing spondylitis in human populations.

HLA B44 is associated with decreased severity of autoimmune lymphoproliferative syndrome in patients with CD95 defects (ALPS type Ia)

Autoimmune lymphoproliferative syndrome (ALPS) is a disorder of lymphocyte apoptosis characterized by non-malignant lymphadenopathy and splenomegaly, expansion of T cells without either CD4 or CD8 surface markers, and increased incidence of autoimmune diseases and lymphoma. Most patients with ALPS have dominant, heterozygous mutations in tumor necrosis factor receptor superfamily member 6 (TNFRSF6), which encodes CD95, also known as Fas, a mediator of apoptosis. Penetrance and range of disease manifestations in ALPS are highly variable, even among family members who share the same dominant TNFRSF6 mutation. To evaluate HLA as a candidate modifier locus, we typed HLA A, B (including subtypes), and DQB alleles in 356 individuals from 63 unrelated families with defined TNFRSF6 mutations associated with ALPS. We also developed a quantitative severity score and performed statistical analysis. Among the healthier, mutation-bearing individuals, transmission of HLA B44 was significantly overrepresented (nominal P<0.0074) as compared to transmission in patients with severe clinical features of ALPS. The B44 allele may exert a protective role in ALPS.

Two HLA-B14 subtypes (B*1402 and B*1403) differentially associated with ankylosing spondylitis differ substantially in peptide specificity but have limited peptide and T-cell epitope sharing with HLA-B27

The peptide specificity of HLA-B*1403, an allotype associated with ankylosing spondylitis (Lopez-Larrea, C., Mijiyawa, M., Gonzalez, S., Fernandez-Morera, J. L., Blanco-Gelaz, M. A., Martinez-Borra, J., and Lopez-Vazquez, A. (2002) Arthritis Rheum. 46, 2968-2971) was compared with those of the non-associated B*1402 and the prototypic disease-associated B*2705 allotypes. Although differing by a single residue (L156R), B*1402 and B*1403 shared only 32-35% of their peptide repertoires. Subtype-related differences observed in multiple peptide positions, including P3 and P7, were largely explained by a direct effect of the L156R change on peptide specificity. The HLA-B14 subtypes shared only approximately 3% of their peptide repertoires with B*2705. This was due to distinct residue usage at most positions, as revealed by statistical comparison of B*1402, B*1403, and B*2705-bound nonamers. Nevertheless, shared ligands between B*2705 and B*1403 were formally identified, although ligands common to B*2705 and B*1403, but absent from B*1402, were not found. Alloreactive T-cells were used as a tool to analyze epitope sharing among B*1402, B*1403, and B*2705. The percentage of cross-reactive T-cell clones closely paralleled peptide overlap, suggesting that shared ligands tend to maintain their antigenic features when bound to the different allotypes. Our results indicate that B*1403 and B*2705 can present common peptides. However, both the disparity of their peptide repertoires and the lack of binding features shared by these two allotypes, but not B*1402, argue against, although do not exclude, a mechanism of spondyloarthritis mediated by specific ligands of B*2705 and B*1403.

New evidence that the MHC influences odor perception in humans: a study with 58 Southern Brazilian students

Increasing evidence suggests a correlation between mate choice, odor preference, and genetic similarity at the Major Histocompatibility Complex (MHC) in a variety of animals, including our species. The MHC is a highly polymorphic group of genes that play an important role in the immunological self/nonself recognition. Its products have been reported to take part on the variety of compounds and reactions that together build an individual's body odor. It has been suggested, therefore, that animals use body odor as a guide to identify possible mates as MHC-similar or MHC-dissimilar from their own genotype. Preference for a MHC-dissimilar partner enhances MHC heterozygosity of an individual's offspring. The possible adaptive advantages are clear: it is a mechanism of avoiding inbreeding and MHC-heterozygous offspring may have enhanced immunocompetence. The aim of this study was to search, in our species, new evidence on the correlation between specificities at HLA-A and HLA-B and assessments of pleasantness regarding specific body odors. HLA is the name for the human MHC. Four olfactory sessions were performed with 58 young Southern Brazilian students, in order to investigate whether assessments of pleasantness of body odors from individuals correlate to a person's HLA phenotype. Body odors were collected via sweat and urine from all participants. Women smelled and scored all male odor samples and men did the same with all female samples. We found a significant correlation only when female smellers evaluated male sweat odors.

A mutation in the HLA-B*2705-restricted NP383-391 epitope affects the human influenza A virus-specific cytotoxic T-lymphocyte response in vitro

Viruses can exploit a variety of strategies to evade immune surveillance by cytotoxic T lymphocytes (CTL), including the acquisition of mutations in or adjacent to CTL epitopes. Recently, an amino acid substitution (R384G) in an HLA-B*2705-restricted CTL epitope in the influenza A virus nucleoprotein (nucleoprotein containing residues 383 to 391 [NP(383-391)]; SRYWAIRTR, where R is the residue that was mutated) was associated with escape from CTL-mediated immunity. The effect of this mutation on the in vitro influenza A virus-specific CTL response was studied. To this end, two influenza A viruses, one with and one without the NP(383-391) epitope, were constructed by reverse genetics and designated influenza viruses A/NL/94-384R and A/NL/94-384G, respectively. The absence of the HLA-B*2705-restricted CTL epitope in influenza virus A/NL/94-384G was confirmed by using (51)Cr release assays with a T-cell clone specific for the NP(383-391) epitope. In addition, peripheral blood mononuclear cells (PBMC) stimulated with influenza virus A/NL/94-384G failed to recognize HLA-B*2705-positive target cells pulsed with the original NP(383-391) peptide. The proportion of virus-specific CD8+ gamma interferon (IFN-gamma)-positive T cells in in vitro-stimulated PBMC was determined by intracellular IFN-gamma staining after restimulation with virus-infected autologous B-lymphoblastoid cell lines and C1R cell lines expressing only HLA-B*2705. The proportion of virus-specific CD8+ T cells was lower in PBMC stimulated in vitro with influenza virus A/NL/94-384G obtained from several HLA-B*2705-positive donors than in PBMC stimulated with influenza virus A/NL/94-384R. This finding indicated that amino acid variations in CTL epitopes can affect the virus-specific CTL response and that the NP(383-391) epitope is the most important HLA-B*2705-restricted epitope in the nucleoprotein of influenza A viruses.

Minor histocompatibility antigens – big in tumour therapy

Technical advances combined with the deciphering of the human genome have facilitated the identification of the molecular nature of human minor histocompatibility (H) antigens. To date, it is believed that minor H antigens result from just any polymorphic protein, regardless of their functional properties. A closer look at the first series of autosomally encoded human minor H proteins reveals a striking functional relationship. Here, we propose that T cells generated after HLA-identical stem cell transplantation (SCT) for malignancies are likely to be directed towards peptides derived from minor H proteins involved in tumourigenesis. This novel insight has important consequences in the search for, and the use of, minor H antigens as immunotherapeutics in stem-cell-based immunotherapy of haematological malignancies and solid tumours.

HLA class I-restricted recognition of an HIV-derived epitope peptide by a human T cell receptor alpha chain having a Vdelta1 variable segment

A subset of human peripheral alpha beta T cells have been shown to express TCR alpha chains containing Vdelta1 segments, although what antigens the Vdelta1(+) alpha beta T cells recognize via these TCR is not known yet. We eventually established a human CD8 T cell clone that expressed alpha beta TCR and Vdelta1 antigens. Corroboratively, a unique in-frame Vdelta1. 1JalphaCalpha transcript was found in the clone. The clone showed cytotoxic activity and IFN-gamma production towards cells expressing HLA-B*3501 pulsed with an HIV Pol-derived epitope peptide (IPLTEEAEL). By flow-cytometric analysis ex vivo using an HLA-B*3501 tetramer, a fraction of Vdelta1(+)CD8(+)tetramer(+) cells was found in peripheral lymphocytes of an HIV-infected patient, indicating the existence of HLA-restricted and HIV-specific Vdelta1(+) CD8 T cells in vivo. Moreover, retrovirus-mediated transfer of the TCR-encoding genes into TCR-negative hybridoma cells showed that the transduced cells were stained by the tetramer and were activated in response to the Pol peptide, further confirming the ligand specificity of the TCR. Together, these results clearly demonstrate that Vdelta1(+) alpha beta TCR are restricted to engaging peptide antigens in the context of classical MHC class I molecules, highlighting the difference in the ligand specificity between Vdelta1(+) alpha beta TCR and Vdelta1(+) gamma delta TCR.

Behçet's disease

Behçet's disease is characterized by recurrent aphthous stomatitis, uveitis, genital ulcers, and skin lesions. The role of the HLA-B*51 gene has been confirmed in recent years, although its contribution to the overall genetic susceptibility to Behçet's disease was estimated to be only 19%. The production of a variety of cytokines by T cells activated with multiple antigens has been shown to play a pivotal role in the activation of neutrophils. As regards the treatment, anti-tumor necrosis factor alpha therapy has been shown to be effective for mucocutaneous symptoms as well as for sight-threatening panuveitis, although a randomized, controlled trial is required.

[Role of HLA phenotype in the formation of chronic hepatitis C virus infection]

Clinical, biochemical and immunological parameters depending on HLA-phenotypic features were examined in 107 patients aged 18-78 years with chronic hepatitis C virus (HCV) infection. Clinical and biochemical manifestations (asthenic, pain and cytolytic syndromes, hepatomegalia, hyperbilirubinemia, hypoprothrombin- and proteinemia), observed in hepatitis C, were more pronounced in patients having HLA-A30, B35, B41, Cw2, A1-B35, A9-B8. The carriers of B8 and B35 antigens were found to have inadequate immune response in HCV infection, manifested by progressive chronic process in the liver and the development of cirrhosis in patients with such specificity.

A single CTL clone can recognize a naturally processed HIV-1 epitope presented by two different HLA class I molecules

Although it is known that a single peptide can be recognized by CTL restricted to two MHC class I alleles, there is no direct evidence for presentation of a single peptide by two MHC class I molecules. Furthermore, it is unclear whether such peptides are presented to the same T cell or to different T cells. Our previous study suggested that CTL recognition of the human immunodeficiency virus-1 (HIV-1) Pol HIV-B35-SF2-24 epitope (IPLTEEAEL) occurs via both HLA-B35 and HLA-B51 restriction. Here we provide the first direct evidence that a single CTL clone can recognize this peptide presented by both HLA-B35 and HLA-B51. Furthermore, we directly purified this peptide eluted from both HLA-B*3501 and HLA-B*5101 molecules isolated from target cells infected with HIV-1 recombinant vaccinia virus. These results demonstrate that HIV-B35-SF2-24 is a naturally processed peptide which is presented by both HLA-B*3501 and HLA-B*5101. TCR analysis of one CTL clone suggested that it is a single clone. B*3501-SF2-24-tetrameric complexes inhibited both HLA-B*3501- and HLA-B*5101-restricted recognition of this clone, suggesting that the TCR of this clone cross-recognize the structure of both HLA class I-peptide complexes.

Major histocompatibility complex phenotypes influence serum testosterone concentration

OBJECTIVES

(a) To confirm our earlier observation that the phenotype HLA-DR4,7 occurs with higher frequency in male patients with rheumatoid arthritis (RA) than in female patients. (b) To test the hypothesis that DR7 is associated with low normal serum testosterone (Te) levels in healthy males; this might explain the increased frequency of DR4,7 in male patients since there appears to be a relationship between low serum Te and RA. (c) To characterize the association between HLA alleles and serum Te concentration in healthy males.

METHODS

An additional 82 Newfoundland (NF) RA patients were HLA-DR typed and, combined with our earlier data and data from the 11th International Histocompatibility Workshop, gave HLA-DR and sex information on 373 RA patients. Ninety-four healthy NF males were typed for HLA, the microsatellite marker TNFa (located close to the tumour necrosis factor alpha gene) and complement factor B (BF). An additional 38 males were included, selected partly based on their HLA-B type.

RESULTS

We confirmed our earlier finding of a higher frequency of HLA-DR4,7 in male RA patients compared with female RA patients (P<0.01). Contrary to our expectations we found that DR7 was associated with higher than mean values of Te as were B5, B27, DR1, TNFa7 and BF F positivity. Conversely, low Te concentrations were found in men with B15, DR2, DR5, TNFa5 and who were BF F negative. In 28 male 'early-onset' RA patients we did not find an increased frequency of HLA alleles associated with low Te levels as compared with the frequency in 41 'late-onset' patients, suggesting that if low Te level is a risk factor and is present before onset of RA then the level cannot be explained by an association between Te level and major histocompatibility complex (MHC) phenotype.

CONCLUSION

This study indicates that a man's MHC phenotype may influence his serum Te concentration, but the relationship of this, if any, to the pathogenesis of RA remains an area of speculation.

Polymorphism in the alpha 1 helix of the HLA-B heavy chain can have an overriding influence on peptide-binding specificity

Previously, we reported overlap in the repertoires of peptides endogenously bound by a group of HLA-B allotypes related to HLA-B7. Extending such analysis to four members of the B17 family and seven members of the B15 family shows that allotypes that share sequence identity in the alpha 1 helix of the class I heavy chain possess markedly similar peptide-binding specificities. Members of the B17 family share a preference for peptides with serine, threonine, or alanine at position 2 and aromatic residues at the carboxyl terminus. Strikingly, the presence of a segment of the B17 alpha 1 helix in B*1516 and B*1517 confers the B17-like peptide-binding motif. The strong influence of natural variation in the alpha 1 helix is exemplified by the differences in peptide-binding specificity of B15 allotypes related by conversion events that replaced segments of the alpha 1 helix. In contrast, evolutionary changes that are confined to the alpha 2 domain confer less dramatic change. They do not perturb the primary anchors of the peptide-binding motif but can modulate the specificity through development and diversification of secondary anchors. Our results, in combination with those obtained previously for other HLA-B allotypes, suggest a general trend whereby polymorphism in the alpha 1 helix is the overriding influence on peptide-binding specificity of HLA-B allotypes, while amino acid substitutions in the alpha 2 domain play a more modulatory role.

Human histocompatibility leukocyte antigen (HLA)-G molecules inhibit NKAT3 expressing natural killer cells

The crucial immunological function of the classical human major histocompatibility complex (MHC) class I molecules, human histocompatibility leukocyte antigen (HLA)-A, -B, and -C, is the presentation of peptides to T cells. A secondary function is the inhibition of natural killer (NK) cells, mediated by binding of class I molecules to NK receptors. In contrast, the function of the nonclassical human MHC class I molecules, HLA-E, -F, and -G, is still a mystery. The specific expression of HLA-G in placental trophoblast suggests an important role for this molecule in the immunological interaction between mother and child. The fetus, semiallograft by its genotype, escapes maternal allorecognition by downregulation of HLA-A and HLA-B molecules at this interface. It has been suggested that the maternal NK recognition of this downregulation is balanced by the expression of HLA-G, thus preventing damage to the placenta. Here, we describe the partial inhibition of NK lysis of the MHC class I negative cell line LCL721.221 upon HLA-G transfection. We present three NK lines that are inhibited via the interaction of their NKAT3 receptor with HLA-G and with HLA-Bw4 molecules. Inhibition can be blocked by the anti-NKAT3 antibody 5.133. In conclusion, NK inhibition by HLA-G via NKAT3 may contribute to the survival of the fetal semiallograft in the mother during pregnancy.

Killer cell inhibitory receptor recognition of human leukocyte antigen (HLA) class I blocks formation of a pp36/PLC-gamma signaling complex in human natural killer (NK) cells

The killer cell inhibitory receptors (KIR) of human natural killer (NK) cells recognize human leukocyte antigen class I molecules and inhibit NK cell cytotoxicity through their interaction with protein tyrosine phosphatases (PTP). Here, we report that KIR recognition of class I ligands inhibits distal signaling events and ultimately NK cell cytotoxicity by blocking the association of an adaptor protein (pp36) with phospholipase C-gamma in NK cells. In addition, we demonstrate that pp36 can serve as a substrate in vitro for the KIR-associated PTP, PTP-1C (also called SHP-1), and that recognition of class I partially disrupts tyrosine phosphorylation of NK cell proteins, providing evidence for KIR-induced phosphatase activity.

Role of HLA-B*5101 binding nonamer peptides in formation of the HLA-Bw4 public epitope

HLA-Bw4 is one of two HLA-B public epitopes which are discriminated by specific alloantisera and mAb. It is believed that the 77-83 of HLA-B molecules form the Bw4 epitope recognized by specific antibodies. This epitope is also recognized by NKB1 receptors on NK cells. We investigated the role of a peptide bound to HLA-B molecules on the formation of the Bw4 epitope recognized by two HLA-Bw4-specific mAb, TU109 and TU48, which recognized the difference of the Bw4 epitope among HLA-B52, -B52 and -B53. Recognition of the HLA-B*5101-peptide complex by these mAb was examined using a panel of HLA-B*5101 binding nonamer peptides. The sequence of HLA-B*5101 binding peptides has a minimum influence on the binding of TU48 mAb to HLA-B*5101 molecules. In contrast, the binding of TU109 mAb to HLA-B*5101 molecules was critically influenced by the sequence of a peptide bound to HLA-B*5101 molecules. TU109 mAb did not recognize HLA-B*5101 binding peptides carrying small or negatively charged residues at P8. The results were confirmed by a panel of mutant peptides at P8. Taken together, these results indicate that a positively charged or neutralized side chain of P8 is critical for the epitope formation of Bw4 recognized by this mAb.

HLA B44-restricted cytotoxic T lymphocyte responses to the peptides of HCV nucleoprotein residues 81-100 in patients with chronic hepatitis C

Human leukocyte antigen B44-restricted cytotoxic T lymphocytes (CTLs) recognize an epitope in hepatitis C virus (HCV) nucleoprotein residues 81-100. CTLs that recognize two wild-type peptides 81-100 of HCV genotypes 1b/II and 2a/III were generated from peripheral blood lymphocytes of each of three patients studied. Although CTLs that recognize a wild-type peptide 81-100 of HCV genotypes 1a/I and 2b/IV were not generated from any patient, CTLs that recognize peptide 81-100 of a rare HCV isolate of type 1a/I were generated from two patients. The results suggest that HLA B44-restricted CTLs recognize most, if not all, HCV isolates of types 1b/II and 2a/III and rare variants of type 1a/I and that the wild-type HCV isolates of genotypes 1a/I and 2b/IV may be less immunogenic for HLA B44-restricted CTLs.

The role of HLA antigens as indicators of disease progression in psoriatic arthritis. Multivariate relative risk model

OBJECTIVE

To identify HLA markers for the development of severe disease in psoriatic arthritis (PsA).

METHODS

Patients with PsA who were followed up prospectively over a 14-year period were included. Clinical and laboratory assessments of both active inflammation and clinical damage were performed at 6-month intervals according to a standard protocol, which also included serologic HLA typing for class I and II antigens. Progression of damage was defined as transition into higher damage states, defined by the number of damaged joints. Both univariate and multivariate models were developed to identify predictors for progression of damage.

RESULTS

Univariate analysis revealed that the HLA antigens B27, B39, and DQw3 were associated with disease progression, while HLA-DR7 was "protective." The best multivariate model identified the HLA antigens B27, when DR7 was present, and DQw3, when DR7 was not present, as predicting disease progression across all transitions, while HLA-B39 was associated with progression in early disease. The addition of these HLA indicators to a model containing clinical variables resulted in a significant improvement in fit.

CONCLUSION

The HLA antigens associated with PsA, B27 and B39, are risk factors for disease progression, as is the HLA class II antigen DQw3. In combination with clinical measures of disease, these HLA variables are the dominant predictors of progression.

Effects of proinflammatory cytokines on cultivated primary human hepatocytes. Fluorometric measurement of intercellular adhesion molecule-1 and human leukocyte antigen-A, -B, -C, and -DR expression

Expression of adhesion molecules and human leukocyte antigens on the surface of hepatocytes (HC) may play an important role in the immune reaction in different types of infectious and noninfectious hepatitis, liver graft rejection, and autoimmune liver diseases. The aim of this study was to evaluate the influence of the proinflammatory cytokines IFN-alpha, IFN-gamma, and IL-1 alpha on the expression of intercellular adhesion molecule-1 (ICAM-1) and HLA-A, -B, -C, and -DR on highly purified primary human HC in cell culture. Expression was assessed by semiquantitative measurement of HC in cell culture by means of computer-aided fluorometry after immunofluorescent labeling. Avidin-biotin-immunoperoxidase staining was applied on parallel cultures to evaluate cell purity (> 99%) and to confirm the results obtained by fluorometry. ICAM-1 was expressed constitutively on untreated HC in vitro. Stimulation of HC with IFN-gamma and IL-1 alpha for 24 hr resulted in an increase of ICAM-1 expression. Cultured HC were moderately HLA-A, -B, and -C positive, but HLA-DR negative. Stimulation of HC with 500 U/ml IFN-gamma for 72 hr resulted in an increase of HLA-A, -B, -C, and -DR expression, whereas stimulation with 10 U/ml IL-1 alpha for 72 hr had no influence. By using 5000 U/ml IFN-alpha for 72 hr, we achieved an increase of HLA-A, -B, and -C expression; effects on the other tested antigens were not significant. In contrast to endothelial cells and transformed human hepatocytic cell lines, ICAM-1 on HC was changed more intensively by IFN-gamma than by IL-1 alpha. Furthermore, the results reveal differences in HLA and ICAM-1 expression between HC in vivo and in vitro.

Excessive function of peripheral blood neutrophils from patients with Behçet's disease and from HLA-B51 transgenic mice

OBJECTIVE

To elucidate the role played by HLA-B51 in the neutrophil hyperfunction of Behçet's disease, we determined the superoxide production by purified peripheral blood neutrophils from Behçet's disease patients, from HLA-B51 positive healthy individuals, and from HLA-B51 transgenic mice.

METHODS

Neutrophil function was evaluated by flow cytometric analysis, detecting the conversion of 2',7'-dichlorofluorescin diacetate into dichloroflurescein, induced by superoxide in the neutrophils.

RESULTS

A significant correlation between the neutrophil hyperfunction and the possession of HLA-B51 phenotype, regardless of the presence of the disease, was observed in humans. FMLP-stimulated neutrophils (without in vitro priming) from HLA-B51 transgenic mice, but not those from HLA-B35 transgenic mice or from nontransgenic mice, produced substantial amounts of superoxide.

CONCLUSION

The HLA-B51 molecule itself may be responsible, at least in part, for neutrophil hyperfunction in Behçet's disease.

NK3-specific natural killer cells are selectively inhibited by Bw4-positive HLA alleles with isoleucine 80

Natural killer (NK) cell clones have been previously described which are inhibited by HLA-C alleles with Asn77-Lys80 (NK1-specific cells) or by HLA-C alleles with Ser77-Asn80 (NK2-specific cells). In the present work, the generation of NK cells with HLA-B-related specificities was attempted by stimulation of a Bw4 homozygous responder by a Bw6 homozygous donor. Two NK clones were found, which were inhibited by HLA-Bw4 (but not by HLA-Bw6) allotypes and by some HLA-A allotypes that share the Bw4 public epitope. Inhibition of NK cell-mediated lysis strongly correlated with the presence of an Ile residue at position 80 of the protective allele. These NK cell clones define a new specificity termed NK3.

Impaired cytotoxic T lymphocyte recognition due to genetic variations in the main immunogenic region of the human immunodeficiency virus 1 NEF protein

Human immunodeficiency virus (HIV) induces strong responses from human histocompatibility leukocyte antigen (HLA) class I-restricted cytotoxic T lymphocytes (CTL). In a previous report we identified an immunodominant region (amino acids 73-144) in the NEF protein that was recognized by CD8+ class I-restricted CTL of most asymptomatic individuals. Analysis of the 73-144 region by peptide sensitization, experiments using overlapping peptides corresponding to the LAI isolate identified the peptide sequences located between residues 73 and 82 or 84 and 92 and the peptide sequence between residues 134 and 144 as cognate peptides for HLA-A11- and HLA-B18-restricted epitopes, respectively. This report describes the variable demonstrable reactivities of CTL obtained from HLA-A11 or HLA-B18 seropositive, asymptomatic patients who all had a response to the virus NEF protein, but who did not always recognize appropriate cognate peptides. The high mutation rate of HIV probably facilitates the selection of mutants that can avoid the cellular immune response. We therefore analyzed the variability of these epitopes restricted by HLA-A11 and HLA-B18. We sequenced several viral isolates from HLA-A11 and HLA-B18 donors who recognized certain HLA-peptide complexes and from those who did not. A CTL sensitization assay was used to show that some mutations led to a great reduction in CTL activity in vitro. This might be due to failure of the mutated epitope to bind major histocompatibility complex class I molecule. A simple assay was used to detect peptides that promoted the assembly of class I molecules. Some of these mutations at major anchor positions prevented HLA-A11/peptide binding, and consequently impaired recognition of the HLA-peptide complex by the T cell receptor.

ME1 epitope of HLA-B27 confers class I-mediated modulation of gram-negative bacterial invasion

We have previously demonstrated that the presence of the MHC class I molecule, HLA-B27, on the surface of transfected fibroblasts differentially alters Gram-negative bacterial invasion as compared with class I alleles that are not implicated in the seronegative spondyloarthropathies. We have now extended this analysis to show that fibroblasts transfected with HLA-B7, a cross-reactive allele with HLA-B27, also demonstrate a similar altered bacterial invasion phenotype. The decrease in the ability of the bacteria to penetrate the HLA-B27 and HLA-B7 transfectants is an invasion-mediated event, as demonstrated by differential invasion events using Escherichia coli transfected with the inv gene of Yersinia enterocolitica. The lysine at position 70, although unique to the HLA-B27 subtypes, is shown to be not involved in mediating the decrease in invasion. However, the ME1 epitope is the critical factor in determining allele-specific alteration in invasion on the basis of the following: 1) ME1 mAb preincubation reverses the decrease; 2) ME1-binding alleles act like HLA-B27; 3) a class I allele that is intermediate in ME1 binding (HLA-B14) also demonstrates a relative decrease in invasion; and 4) mutation at residue 67 (C-->Y) in HLA-B27, which eliminates the ME1 epitope, normalizes the decreased invasion seen in the native HLA-B27-transfected cells. Thus, the ME1 epitope relates to the disease susceptibility for reactive arthritis that is conferred by both HLA-B27 and cross-reactive group Ags.

HLA B44-restricted cytotoxic T lymphocytes recognizing an epitope on hepatitis C virus nucleocapsid protein

Cytotoxic T lymphocytes have been reported to be involved in the immune clearance of virus-infected cells and in the pathogenesis of viral infection. We studied the cytotoxic T lymphocyte response to the putative nucleocapsid protein of hepatitis C virus in patients with chronic hepatitis C. Cytotoxic T lymphocytes specific for hepatitis C virus nucleocapsid protein were generated from peripheral blood lymphocytes by means of repeated stimulation with a synthetic hepatitis C virus nucleocapsid protein peptide. The cytotoxic T lymphocytes were CD8 positive and recognized an epitope in hepatitis C virus nucleocapsid protein residues 81 to 100 in association with a human leukocyte antigen class I molecule, B44. The peptide-induced cytotoxic T lymphocytes recognized target cells synthesizing hepatitis C virus nucleocapsid protein endogenously, though less efficiently than peptide-pulsed target cells. The human leukocyte antigen B44-restricted cytotoxic T lymphocyte response was observed in three of five patients with chronic hepatitis C and a human leukocyte antigen B44 molecule but in neither of two hepatitis C virus-negative healthy individuals with human leukocyte antigen B44 molecules. The results demonstrate the presence of hepatitis C virus-specific cytotoxic T lymphocytes in the peripheral blood of patients with chronic hepatitis C and provide a strategy to study the role of cytotoxic T lymphocytes in the viral clearance and the pathogenesis of hepatitis C virus infection.

Differences in the expression of spondyloarthropathy: a comparison between ankylosing spondylitis and psoriatic arthritis

The aim of the study was to compare the spondyloarthropathy of ankylosing spondylitis (AS) to that of psoriatic arthritis (PsA). Forty patients with AS and 66 patients with PsA underwent a complete assessment according to a standard protocol, including radiographic evaluation and HLA typing. A logistic regression analysis was performed controlling for age, arthritis duration, and sex. A higher frequency of inflammatory neck and back pain and stiffness (p < 0.0002), limitation of back movements (p < 0.0006), grade 4 sacroiliitis (p = 0.007), and syndesmophytes (p = 0.005) was noted in AS, while peripheral arthritis was more common and more severe in patients with PsA (p = 0.002). A lower frequency of HLA B17 (p = 0.02), and a higher frequency of HLA B27 (p = 0.0001), and Cw2 (p < 0.01) was found in AS compared to PsA. Thus, there are clinical, radiologic, and genetic differences in disease expression of the SA of AS and PsA, supporting their classification as distinct entities.

Expression of epidermal-growth-factor receptor in the K562 cell line by transfection. Altered receptor biochemistry

The epidermal-growth-factor (EGF) receptor was expressed in the human erythroleukaemic cell line K562 by transfection of the receptor cDNA. EGF-receptor biochemistry appears altered in the K562 transfectants. Autophosphorylation of the K562 receptor is not stimulated substantially by EGF. Tyrosine kinase activity of the receptor is high in the absence of EGF, whereas receptor affinity for EGF is low. K562 cells are shown to lack mRNA for transforming growth factor alpha (TGF alpha). Therefore autocrine stimulation of the K562 receptor, at least by TGF alpha, does not explain the observed receptor biochemistry. The K562 receptor is phosphorylated at a single major site in intact cells, a threonine residue that may be Thr-669. Possible mechanisms of regulation of the EGF receptor in the K562 transfectants are discussed.

HLA-Bw54-DR4-DRw53-DQw4 haplotype controls nonresponsiveness to hepatitis-B surface antigen via CD8-positive suppressor T cells

We have previously reported that in nonresponders to hepatitis-B (HB) vaccine there was an HLA-linked immune suppression gene for hepatitis-B surface antigen (Is-HBsAg) controlling the nonresponsiveness to HBsAg, through HBsAg-specific suppressor T cells, and that the Is-HBsAg was in strong linkage disequilibrium with the HLA-Bw54-DR4-DRw53 haplotype (1). We have now done the HLA typing on an additional 6 nonresponders, and using the system of T-cell proliferative response to HBsAg we found that the Is-HBsAg controlled the nonresponsiveness to HBsAg through HBsAg-specific suppressor T cells in nonresponders to HB vaccine who have HLA-Bw54-DR4-DRw53-DQw4 haplotype. T- and B-cell recognition of HB vaccines might play an important role at 3 to 5 weeks after the last immunization. Use of an anti-HLA monoclonal antibody has shown that the HLA-DR molecule plays an important role in helper T-cell proliferation in nonresponders, although the role of HLA-DQ molecule in nonresponders was unclear.