Genetic predetermination of quantitative expression of HLA antigens in platelets and mononuclear leukocytes

In view of the potential functional importance of quantitative expression of HLA antigens, a series of studies were conducted to determine the relative quantities of specific HLA-A and -B antigens expressed in MNLs and platelets of HLA-phenotyped family members and unrelated individuals. An mAb that reacts with a well-defined monomorphic epitope in the α₃ domain of the heavy chains of HLA molecules was developed and used to quantify each HLA-A or -B antigen on western blots of IEF gels. The results of these studies demonstrated that the relative quantities of HLA-A and -B antigens in platelets and MNLs of an individual did not change over time. Further studies showed that the relative quantities of HLA-A and -B antigens for haplotypes shared among the first-degree relatives were always the same and followed Mendelian inheritance. In contrast, the relative quantities of HLA-A and -B antigens for a haplotype shared by unrelated individuals varied significantly. All these findings support the hypothesis that the quantitative expression of HLA antigens is genetically predetermined and may play important roles in determining disease susceptibility and severity. Human Immunology 38, 243–250 (1993)     

Peptides derived from the whole sequence of BCR-ABL bind to several class I molecules allowing specific induction of human cytotoxic T lymphocytes

Chronic myeloid leukemia (CML) is characterized cytogenetically by a t(9;22) translocation which generates a hybrid bcr-abl gene, encoding a p210^bcr-abl fusion protein. The induction in vitro of leukemia-specific T cells reactive with p210^bcr-abl is a strategy developed for an immunological therapeutic approach in CML. Peptides from the junction region of this chimeric protein have been considered as potential targets for a cytotoxic response against leukemic cells. However, only a few peptides encompassing the two p210^bcr-abl breakpoints have been shown to bind to the most common HLA class I molecules, which limits the number of patients who could benefit from this approach. We assume that the presence of chimeric BCR-ABL protein in leukemic cells may affect processing and delivery of peptides, possibly giving rise to new epitopes at the cell surface. We selected 162 peptides from the whole sequence of this protein, including 14 peptides of the b2a2 and b3a2 junctions, which had an anchor motif for a common HLA class I molecule. We tested their ability to bind to eight HLA class I molecules (HLA-A1, -A2, -A3, -A11, -B7, -B8, -B27, -B44). We identified 48 peptides from outside the junction region, with intermediate or strong binding capacities to these HLA class I molecules contrasting with only six junction peptides with a moderate binding capacity to HLA-A3/A11, -B8, or -B44 molecules. Moreover, cytotoxic T lymphocyte lines specific for various peptides outside the junction were generated from peripheral blood mononuclear cells of HLA-A2 or -B7 healthy donors and from one CML patient. These results contribute to evaluation of immunity to the BCR-ABL chimeric protein. Further studies are required to investigate whether such epitopes are correctly processed and presented by leukemic cells.     

Human mumps virus-specific cytotoxic T lymphocytes: quantitative analysis of HLA restriction

To obtain quantitative information about the use of HLA antigens as restriction element by antiviral cytotoxic T lymphocytes (CTL), we have analyzed precursors of human mumps virus-specific CTL by limiting dilution. CTL generated by restimulation of peripheral blood T lymphocytes with autologous mumps virus (MV)-infected stimulator cells were restricted by autologous HLA class I antigens, and derived from the T4-8+ population. They were specific for MV and did not lyse autologous target cells infected with other viruses. Frequencies of MV-specific CTL precursors ranged from 1/500 to 1/8000. HLA restriction was analyzed by split-well analysis of individual CTL colonies. CTL recognizing HLA-A or B antigens were unequally distributed: HLA-B7, -B13, and -B27 were found to function as predominant, in some cases as exclusive, restriction elements, whereas other antigens such as HLA-A24 were never or rarely used. In several combinations, there was no evidence for antigenic variants of HLA molecules as reason for the failure to be recognized. The proportion of CTL precursors recognizing HLA-A2 and -B8 seemed to be dependent on the presence or absence of "dominant" restriction elements. We conclude that CTL precursors recognizing certain virus-HLA combinations are preferentially expanded during an infection, but that low responsiveness to a given combination is not necessarily absolute.     

Evaluation of individual specificities of class I HLA on platelets by a newly developed monoclonal antibody

In order to quantify each specific HLA-A or-B antigen on platelets, a monoclonal antibody against HLA heavy chains was developed and designated as 2F2 monoclonal antibody. This monoclonal antibody reacted on Western blot with platelet HLA from each 10 individuals with different HLA phenotypes and precipitated all ³⁵S-methionine-labeled HLA-A and -B antigens from three different Epstein-Barr Virus-transformed lymphoblastoid cell lines. The results indicate that the 2F2 monoclonal antibody recognizes an epitope shared by different HLA-A and -B antigens. The quantitative variation of specific HLA antigens on platelets was then studied in nine different donors by isoelectric-focusing gel electrophoresis and immunoblot using the 2F2 monoclonal antibody. The results of our studies showed that the shared HLA antigens such as A2, B35, and B62, varied three- to fivefold among different individuals and individual HLA-A or -B antigen was not equally expressed on a person's platelets. The relative quantities of specific HLA-A and -B antigens on lymphocytes were also noted to be the same as those on platelets. The finding suggests that differential expression of HLA specificities may not be restricted to platelets but is a more general phenomenon including other nucleated cells.     

HLA class I association with progression to end-stage renal disease in patients from Zulia,Venezuela

The aim of this study was to determine HLA associations with progression to end-stage renal disease (ESRD) in the mixed Zulian population in Venezuela, regardless of other factors. A retrospective study to determine HLA Class I association was performed on 188 patients with ESRD due to different types of glomerulonephritis, and 202 healthy controls. Patients and control groups were serologically typed by Terasaki microlymphocytotoxicity technique using commercial Class I plates including 26 HLA-A and 48 HLA-B specificities. The antigens positively associated to the ESRD were: HLA-B38, B51, B53 and B62. Negatively associated antigens were: HLA-A9, B12, B17, B40 and B48. The haplotypes positively associated were: HLA-A2-B51, A2-B53, A23-B38 and A68-B38. The negatively associated haplotypes were: HLA-A2-B12, A2-B48, A9-B35 and A28-B40. The high Odds ratio observed and its statistical corroboration reflect the strength of the described association between HLA antigens and ESRD. Further molecular studies should clarify types and subtypes of the HLA class I alleles involved in the progression to ESRD.     

Allotyping for HLA class I using plasma as antigen source

Immunoadsorption of soluble HLA class I antigens onto immunobeads, one-dimensional iso-electric focusing of these proteins and subsequent immunoblotting allows a biochemical identification of HLA class I allotypes. The distinct protein bands can be clearly attributed to particular HLA antigens and are comparable to those observed after detergent solubilization of membrane-bound HLA antigens. Segregation analysis showed that the biochemically detected pattern of soluble class I gene products followed Mendelian inheritance. However, antigens such as HLA-A1, -A2, -B8, and -B51 were not always clearly detectable, a phenomenon attributable to either different plasma concentrations of these HLA antigens or variable affinity of the monoclonal antibody used to capture class I antigens. These results show that in principle allotyping of HLA class I using plasma as the antigen source is feasible, but with the limitation that some antigens may not be easily detected in some individuals.     

HLA Histocompatibility Antigens in a Polynesian Population — Cook Islanders of Mauke

Polynesians living on the island of Mauke in the Cook Island group were typed for HLA-A and -B locus antigens. The Mauke population has restricted HLA polymorphism, with five A-locus antigens and four B-locus antigens accounting for a majority of the HLA phenotypes. Although some differences in antigen frequency were found when Mauke Islanders were compared with Polynesians from Easter Island and Samoa, the Mauke Islanders were closer in their HLA antigenic profile to polynesians than to Melanesians.     

Lymphocytes modulated by β interferon express new non-HLA-A,B,C class I antigens

Peripheral blood lymphocytes were cultured with recombinant β interferon (INF-lymph). Three days in culture and 5 × 10⁴ units/ml produced the best modulatory effect. Platelet absorbed alloantisera previously shown to contain non-HLA-A,B,C class I antibodies were tested with the INF-lymph. The serologic reactivity could be blocked by turkey sera to human B₂-microglobulin but not by turkey anti-Ia-like. Absorption studies with INF-lymph obtained from donors expressing different HLA antigens indicated that the serologic reactivity is not due to HLA. Fourteen sera appeared to cluster in three groups, only one of which was found to be associated with HLA (HLA-A1). Antigenic modulation of INF-lymph obtained from HLA-A1⁺ individuals with HLA-A1 typing alloantisera eliminated subsequent lysis mediated by HLA-A1 alloantibodies and complement but not lysis with platelet absorbed antibodies included in the cluster associated with HLA-A1. These findings suggest independence from HLA-A1 and coexpression of HLA-A1 and A1-associated class I antigens. Family studies indicated that the reactivities segregated with HLA thus mapping it to chromosome VI. Similar to what we have described with PHA, β interferon modulates lymphocytes and induces the expression of new class I differentiation antigens probably analogous to the murine Qa-T1a antigens.     

Detection of HLA antigens on blood platelets and lymphocytes by means of monoclonal antibodies in an ELISA technique

The expression of HLA-A and -B antigens on peripheral blood lymphocytes and blood platelets was measured using monoclonal antibodies in a semi-quantitative ELISA technique. Reactively of monoclonal anti-HLA-A2 and anti-HLA-B7, with lymphocytes as well as platelets, was in agreement with the presence of these antigens as detected by conventional HLA typing of lymphocytes. When the actual amount of HLA antigens was measured, a gene-dose effect was seen: cells from HLA-B7-homozygous individuals bound more monoclonal anti-HLA-B7 antibodies compared to their HLA-B7-heterozygous siblings. At the same time, cells of different donors showed only very small differences in binding of monoclonal antibody against an HLA-"backbone" determinant. Relative to total HLA-A, -B and -C expression, the amounts of HLA-A2 on lymphocytes and platelets were similar. On the other hand, the expression of HLA-B7 on platelets was diminished compared to that on peripheral blood lymphocytes.     

Tissue Typing of Cells in Culture. IV. Cell Surface Antigens of Tumor Cell Lines, not Obviously Belonging to the HLA-System

Studies on the HLA pattern of several human tumor cell lines by the mixed hemadsorption test and also studies on the discriminative patterns formed by a collection of sera on a number of cell lines and diploid cells have been reported elsewhere. It was noted during these studies that some sera reacted in a fashion indicating that they did not represent any of the HLA-A or -B series and probably not the HLA-C series either. The corresponding antigenic determinants were tentatively designated Ek-1 to Ek-11. The pattern of these antigens among the cell lines is given in a table and it seems apparent that the Ek-series considerably increases the cell identification potential of the typing results. So far, five of the sera determining the Ek-antigens have failed to be blocked by anti-beta-2-microglobulin, indicating that the antigens do not belong to the HLA-A, B or C series. Preparatory work for HLA-D typing is under way.     

The HLA-DR phenotype of the responder is predictive of humoral response against HLA class I antigens

Recent studies suggest that the immunogenicity of an human leukocyte antigen (HLA) incompatibility should be considered in the context of the HLA phenotype of the recipient. The HLA-DR phenotype of the responder is thought to be predictive for the strength of the alloimmune response. In order to analyze the humoral response against HLA class I antigens in the context of the HLA-DR phenotype of the responder, we selected all HLA-DR homozygous Dutch patients that were present on the Eurotransplant waiting list between 1967 and 2000 (n=1,317 patients). By logistic regression it was determined whether antibody production against a specific HLA class I antigen is associated with a particular HLA-DR antigen in the patient. Furthermore, it was analyzed whether a patient, expressing a particular HLA-DR antigen, preferentially produces antibodies against particular HLA class I antigens. The results demonstrate that patients, homozygous for a certain HLA-DR antigen, cannot be considered high or low responders when analyzing the antibody response in terms of panel reactive antibody (PRA) value. However, a correlation can be found between the HLA-DR phenotype of the patient and the specific antibody response against HLA class I antigens. For example, antibodies against HLA-A10, -A11, -A19, and -B35 are produced more frequently by HLA-DR6 positive individuals, whereas antibodies against HLA-A3, -B5, -B7, -B8, and -B12 are produced more frequently by HLA-DR4 positive individuals. These data confirm that the HLA-DR phenotype of the responder plays a determinative role in the immunogenicity of mismatched HLA antigens. The results indicate that selection of HLA class I mismatches of the donor in the context of the HLA-DR phenotype of the responder might reduce the incidence of humoral graft rejection and minimize the sensitization grade of retransplant candidates.     

The role of the human major histocompatibility complex in cytotoxic T-cell responses to virus-infected cells

The human major histocompatibility complex (HLA) has been demonstrated to play two roles in the generation and expression of cytotoxic T-lymphocyte responses to virusinfected cells: (1) cytotoxic T cells can only recognize viral antigens in conjunction with antigens encoded by HLA-A and -B genes; and (2) HLA-linked genes may control the capacity to generate T-cell responses to a given virus or to virus in conjunction with particular self HLA-A and -B antigens. Analysis of T-cell responses generatedin vivo to Epstein-Barr virus suggests that human T cells may recognize virus in conjunction with antigens other than the class I HLA polymorphic specificities.     

Structure, Function, and Biosynthesis of the Major Human Histocompatibility Antigens (HLA-A and HLA-B)

Summary
In summary, the complete primary structure of one HLA antigen (HLA-B7) has now been determined, and sufficient information is available about other HLA-A and -B and H-2 molecules to begin to assess the location of the variable regions within these molecules. It is these regions of the molecules which have evolved to give rise to the extensive polymorphism in human populations, and they most likely define functionally important regions of the molecule. Thus, this information may help us to elucidate the natural biological function of these molecules, as, for example, in the recognition of allogeneic or virally infected syngeneic cells by cytotoxic T cells. Some functional studies, using purified HLA-A and -B antigens inserted in liposomes, have been initiated, and studies of the biosynthesis of these antigens are of great interest in their own right. Further, using cDNA probes, they are being extended to permit us ultimately to underScand the organization of the genes on the sixth human chromosome which encode HLA-A and -B antigens. Finally, such probes may permit the rapid accumulation of sequence information, which would allow us to underScand more completely the structure of these extremely important cell surface molecules.     

Polymorphism of HLA-A, -B, -DRB1, -DQA1 and -DQB1 haplotypes in a Croatian population.

We describe for the first time extended haplotypes in a Croatian population. The present study gives the HLA-A, -B, -DRB1, -DQA1 and -DQB1 allele and haplotype frequencies in 105 families with at least two offspring. All individuals were studied by conventional serology for HLA class I antigens (A and B), while class II alleles (DRB1, DQA1, DQB1) were typed using the PCR-SSOP method. HLA genotyping was performed by segregation in all 105 families. For extended haplotype analysis, 420 independent parental haplotypes were included. Fourteen HLA-A, 18 HLA-B, 28 DRB1, 9 DQA1 and 11 DQB1 alleles were found in the studied population. Most of the DRB1 alleles in our population had an exclusive association with one specific DQA1-DQB1 combination. This strong linkage disequilibrium within the HLA class II region is often extended to the HLA-B locus. A total of 10 HLA-A, -B, -DRB1, -DQA1, -DQB1 haplotypes were observed with a frequency 相似文献   

The polymorphisms of intron1 sequences of HLA-A and -B

Human leucocyte antigen (HLA) class I antigens are highly polymorphic membrane glycoproteins present on most nucleated cells. The polymorphism region is mainly located in exons 2 and 3 of HLA class I genes, which is flanked by introns 1 and 3. Thus, the sequence information of introns 1 and 3 is important for the genotyping of HLA. However, the information about them has not been extensively reported by now. In this work, the intron 1 sequences of HLA-A and -B of 51 standard genomic DNAs provided by the 13th International Histocompatibility Work Group (IHWG) were cloned and sequenced. The polymorphism of the intron sequences were also analyzed by the software Clustal W 1.82. Some sequences were chosen to compare with the standard sequences published in National Center for Biotechnology Information (NCBI). The comparison showed that all the sequences matched exactly with the standard sequences. The knowledge of intron 1 sequences could be very important not only for developing DNA-based typing strategies for the HLA-A and -B alleles but also for establishing an understanding of the evolutionary mechanisms involved in the polymorphism generation of HLA class I alleles.     

Polymorphisms of HLA genes in Western Javanese (Indonesia): close affinities to Southeast Asian populations

Identification of human leukocyte antigen (HLA) antigens that are known as the highest polymorphic genes has become a valuable tool for tissue transplantation, platelet transfusion, disease susceptibility or resistance, and forensic and anthropological studies. In the present study, the allele and haplotype frequencies of HLA-A, HLA-B, and HLA-DRB1 were studied in 237 unrelated healthy Western Javanese (Indonesia) by the high-resolution polymerase chain reaction-Luminex method. A total of 18 A, 40 B, and 20 DRB1 alleles were identified. The most frequent HLA-A, -B, and -DRB1 alleles were HLA-A*2407 (21.6%), HLA-B*1502 (11.6%) and HLA-B*1513 (11.2%), and DRB1*1202 (37.8%), respectively. The most frequent two-locus haplotypes were HLA-A*2407-B*3505 (7%) and HLA-B*1513-DRB1*1202 (9.2%), and three-locus haplotypes were HLA-A*3401-B*1521-DRB1*150201 (4.6%), HLA-A*2407-B*3505-DRB1*1202 (4.3%), and HLA-A*330301-B*440302-DRB1*070101 (4.2%). HLA allele and haplotype frequencies in addition to phylogenetic tree and principal component analyses based on the four-digit sequence-level allele frequencies for HLA-A, HLA-B, and HLA-DRB1 showed that Western Javanese (Indonesia) was closest to Southeast Asian populations.     

HLA antigens and Graves' disease in Black South Africans

This study concerns the frequencies with which 36 HLA-A, -B and -C antigens occurred in 84 Black Africans with Graves' disease and in 311 Black controls. In the hyperthyroid patients significant reductions were found in the frequencies of HLA-B7 ( P <0.001, relative risk (RR) 0.33), HLA-Bw42 ( P <0.001, RR 0.32) and the HLA-B7-Bw42 crossreactive group (CREG) ( P <0.0001, RR 0.27), and in the frequencies of the phenotypic combinations HLA-A1, B7 ( P <0.001) and Aw30, B7-Bw42 ( P <0.001). HLA-B8 was increased in frequency ( P <0.01, RR 2.84). In patients without circulating antithyroglobulin or antimitichondrial antibodies the frequencies of HLA-A2 and B17 were increased when compared to those with antibodies or to the controls. In patients with and without clinically evident infiltrative ophthalmopathy the frequencies of HLA antigens were similar. In 62 Caucasian patients with Graves' disease, no antigens or phenotypic combinations occurred with increased or decreased frequency when compared to 278 controls.
Analysis of the frequencies of 9 HLA antigens and phenotypic combinations common in Caucasians but rare in Blacks revealed that only two antigens (A2 and B8) occurred with increased frequency in Black patients, suggesting that a contribution of Caucasian genes to the Black thyrotoxic subjects was unlikely.
Similarly, only one common Black antigen (A28) of 8 common antigens and phenotypic combinations, occurred in Caucasian patients with a frequency similar to that of Black controls. Thus it is unlikely that Black genes contributed to the lack of a significant increase of HLA antigens in the Caucasian thyrotoxic patients. The possession of HLA-B7-Bw42 CREG or related genes may be a protection against Graves' disease in Black Africans.     

Major histocompatibility complex (MHC) antigens polymorphism and alloimmunization study in thalassemia patients with febrile non-hemolytic transfusion reaction (FNHTR)

ObjectivesHLA alloimmunization is one of the most troublesome consequence of regular transfusion which is itself a mainstay measure to provide longevity to the thalassemia patients. Febrile non-hemolytic transfusion reaction (FNHTR) is one of the most common complication which might be related to the HLA alloimmunization. Here, we studied the HLA antigenic system and alloimmunization rate in the Iranian β-thalassemia patients who suffered from FNHTR compare to the β-thalassemia patients without FNHTR.Materials & methodsTotal of 60 β-thalassemia patients with FNHTR (case group) and 20 β-thalassemia patients without FNHTR (control group) randomly have been selected and enrolled in the study. All were tested for HLA-A and -B loci by PCR-SSP method and also for the presence of anti-lymphocyte antibodies by LIFT method. Comparisons between two groups were performed by Pearsonʼs χ2 test.ResultsTotally, a significant predominance was noted for two HLA alleles, HLA-A*24 (P = 0.029) and B*55 (P = 0.034) which have higher prevalence in control group. Although no significant association was found between the presence of anti-leukocyte antibodies and the development of FNHTR, the HLA-A*32 (P = 0.047) allele was considered as possible genetic markers in the susceptibility to the development of anti-leukocyte antibodies.ConclusionHere some evidences about the possible role of HLA polymorphism in susceptibility to FNHTR are provided. Those results indicated that HLA-A*24 and HLA-B*55 might play protective role on inducing FNHTR in β-thalassemia patients. Further studies which investigate the allele level of HLA-I alongside with specific reactivity of HLA-I antibodies might reveal more deep data about these phenomena.