Complexity among constituents of the HLA-B*1501 peptide motif

 Analysis of peptides derived from HLA class I molecules indicates that thousands of unique peptides are bound by a single molecular type, and sequence examination of the pooled constituents yields a motif which collectively defines the peptides bound by a given class I molecule. Motifs resulting from pooled sequencing are then used to infer whether particular viral and tumor protein fragments might serve as class I-presented peptide therapeutics. Still undetermined from a pooled motif is the breadth or range of peptides in the population which are brought together to form the pooled motif, and it is therefore not yet known how representative of the population a pooled motif is. By employing hollow fiber bioreactors for large-scale production of HLA class I molecules, sufficient peptides are produced to investigate individual subsets of peptides comprising a motif. Edman sequencing and mass spectrometric analysis of peptides eluted from HLA-B^*1501 reveal that many peptide sequences fail to align with either the N- or C-terminal anchors predicted for the B^*1501 peptide motif through whole pool sequencing. These analyses further reveal auxiliary anchors not previously detected and peptides significantly larger and smaller than the predicted nonamer, ranging from 6 to 12 amino acids in length. These results demonstrate that constituents of the B^*1501 peptide pool vary markedly in comparison with one another and therefore in comparison with previously established B^*1501 motifs, and such complexity indicates that many of the peptide ligands presented to CTL cannot be predicted using class I consensus motifs as search criteria. Received: 7 October 1997 / Revised: 10 December 1997     

Binding of nonamer peptides to three HLA-B51 molecules which differ by a single amino acid substitution in the A-pocket

The interaction between 9-mer peptides and HLA-B51 molecules was investigated by quantitative peptide binding assay using RMA-S cell expressing human β2-microglobulin and HLA-B51 molecules. Of 147 chemically synthesized 9-mer peptides possessing two anchor residues corresponding to the motif of HLA-B^*5101 binding self-peptides, 27 paptides bound to HLA-B^*5101 molecules. Pro and Ala at position 2 as well as Ile at position 9 were confirmed to be main anchor residues, while Gly at position 2 as well as Val, Leu, and Met at position 9 were weak anchor residues for HLA-B^*5101. The A-pocket is suspected to have a critical role in peptide binding to MHC class I molecules because this pocket corresponds to the N-terminus of peptides and has a strong hydrogen bond formed by conserved Tyr residues. Further analysis of peptide binding to HLA-B^*5102 and B^*5103 molecules showed that a single amino acid substitution of Tyor for His at residue 171(B^*5102) and that of Gly for Trp at residue 167 (B^*5103) has a minimum effect in HLA-B51-peptide binding. Since previous studies showed that some HLA-B51 alloreactive CTL clones failed to kill the cells expressing HLA-B^*5102 or HLA-B^*5103, these results imply that the structural change of the A-pocket among HLA-B51 subtypes causes a critical conformational change of the epitope for TCR recognition rather than influences the interaction between peptides and MHC class I molecules.     

Residue 116 determines the C-terminal anchor residue of HLA-B*3501 and -B*5101 binding peptides but does not explain the general affinity difference

 HLA-B^*3501 and -B^*5101 molecules, which belong to the HLA-B5 cross-reactive group, bind peptides carrying similar anchor residues at P2 and the C-terminus, but differences are observed in the preference for a Tyr residue at the C-terminus and the affinity of peptides. A recent study of HLA-B^*3501 crystal structure suggested that residue 116 on the floor of the F-pocket determines a preference for anchor residues at the C-terminus. In order to evaluate the role of the residue 116 in the peptide binding to both HLA-B^*3501 and HLA-B^*5101 molecules, we generated HLA-B^*3501 mutant molecules carrying Tyr at residue 116 (B^*3501–116Y) and tested the binding of a panel of nonamer peptides to the B^*3501–116Y molecules by a stabilization assay with RMA-S transfectants expressing the mutant molecules. The substitution of Tyr for Ser at residue 116 markedly reduced the affinity of nonamer peptides carrying Tyr at P9, while it enhanced that of nonamer peptides carrying Ile and Leu at P9. On the other hand, the affinity of peptides carrying aliphatic hydrophobic residues at P9 to B^*3501–116Y molecules was much higher than that to HLA-B^*3501 and HLA-B^*5101 molecules. These results indicate that residue 116 is critical for the structural difference of the F-pocket between HLA-B^*3501 and HLA-B^*5101 which determines the C-terminal anchor residues, while leaving other residues which differ between HLA-B^*3501 and HLA-B^*5101 may be responsible for the low peptide binding property of the latter. Received: 18 April 1997 / Revised: 18 September 1997     

HLA-B alleles of the Cayapa of Ecuador: new B39 and B15 alleles

Recent data suggest that HLA-B locus alleles can evolve quickly in native South American populations. To investigate further this phenomenon of new HLA-B variants among Amerindians, we studied samples from another South American tribe, the Cayapa from Ecuador. We selected individuals for HLA-B molecular typing based upon their HLA class II typing results. Three new variants of HLA-B39 and one new variant of HLA-B15 were found in the Cayapa: HLA-B ^*3905, HLA-B^*3906, HLA-B^*3907, and HLA-B ^*1522. A total of thirteen new HLA-B alleles have now been found in the four South American tribes studied. Each of these four tribes studied, including the Cayapa, had novel alleles that were not found in any of the other tribes, suggesting that many of these new HLA-B alleles may have evolved since the Paleo-Indians originally populated South America. Each of these 13 new alleles contained predicted amino acid replacements that were located in the peptide binding site. These amino acid replacements may affect the sequence motif of the bound peptides, suggesting that these new alleles have been maintained by selection. New allelic variants have been found for all common HLA-B locus antigenic groups present in South American tribes with the exception of B48. In spite of its high frequency in South American tribes, no evidence for variants of B48 has been found in all the Amerindians studied, suggesting that B48 may have unique characteristics among the B locus alleles.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers U14756 (HLA-B ^*1522), U15683 (HLA-B ^*3905), U15639 (HLA-B ^*3906), and U15640 (HLA-B ^*3907)The names listed for these sequences were officially assigned by the WHO nomenclature Committee in September 1994, B ^*3905, and November 1994, B ^*1522, B^*3906, and B ^*3907. This follows the agreed policy that, subject to the conditions stated in the most recent Nomenclature Report (Bodmer et al. 1994), names will be assigned to the new sequences as they are identified. Lists of such new names will be published in the following WHO Nomenclature Report.     

Polymorphic sites away from the Bw4 epitope that affect interaction of Bw4+ HLA-B with KIR3DL1

KIR3DL1 is a polymorphic, inhibitory NK cell receptor specific for the Bw4 epitope carried by subsets of HLA-A and HLA-B allotypes. The Bw4 epitope of HLA-B*5101 and HLA-B*1513 is determined by the NIALR sequence motif at positions 77, 80, 81, 82, and 83 in the alpha(1) helix. Mutation of these positions to the residues present in the alternative and nonfunctional Bw6 motif showed that the functional activity of the Bw4 epitopes of B*5101 and B*1513 is retained after substitution at positions 77, 80, and 81, but lost after substitution of position 83. Mutation of leucine to arginine at position 82 led to loss of function for B*5101 but not for B*1513. Further mutagenesis, in which B*1513 residues were replaced by their B*5101 counterparts, showed that polymorphisms in all three extracellular domains contribute to this functional difference. Prominent were positions 67 in the alpha(1) domain, 116 in the alpha(2) domain, and 194 in the alpha(3) domain. Lesser contributions were made by additional positions in the alpha(2) domain. These positions are not part of the Bw4 epitope and include residues shaping the B and F pockets that determine the sequence and conformation of the peptides bound by HLA class I molecules. This analysis shows how polymorphism at sites throughout the HLA class I molecule can influence the interaction of the Bw4 epitope with KIR3DL1. This influence is likely mediated by changes in the peptides bound, which alter the conformation of the Bw4 epitope.     

Genetic and serological heterogeneity of the supertypic HLA-B locus specificities Bw4 and Bw6

Gene cloning and sequencing of theHLA-B locus split antigens B38 (B16.1) and B39 (B16.2) allowed localization of their subtypic as well as their public specificities HLA-Bw4 or-Bw6 to the α-helical region of the α 1 domain flanked by the amino acid positions 74–83. Comparison of their amino acid sequences with those of otherHLA-B-locus alleles established HLA-Bw6 to be distinguished by Ser at residue 77 and Asn at residue 80. In contrast, HLA-Bw4 is characterized by at least seven different patterns of amino acid exchanges at positions 77 and 80–83. Reactivity patterns of Bw4-or Bw6-specific monoclonal antibodies reveal two alloantigenic epitopes contributing to the HLA-Bw4 or-Bw6 specificity residing next to the region of highest diversity of the α 1 domain.     

Binding of 8-mer to 11-mer peptides carrying the anchor residues to slow assembling HLA class I molecules (HLA-B*5101)

 The binding of 303 8-mer to 11-mer peptides carrying the anchor residues at P2 and the C-terminus to HLA-B^*5101 molecules was examined by a stabilization assay in which peptides were incubated with RMA-S-B^*5101 cells at 26 °C for 3 h. Analysis of the binding of these peptides to HLA-B^*5101 molecules showed that Pro and Ala at P2, and Ile, Val, and Leu at the C-terminus functioned as anchor residues, while Gly at P2 and Met at the C-terminus were weak anchors. Pro was a stronger anchor residue than Ala at P2, while Ile was the strongest anchor at the C-terminus. Among 8-mer to 11-mer peptides, the 9-mer peptides showed the strongest binding to HLA-B^*5101 molecules. This is in contrast to our recent findings that 10-mer and 11-mer peptides bind to HLA-B^*3501 molecules as effectively as 9-mer peptides. Since both HLA class I molecules have the same B-pocket and the binding peptides carry the same anchor residues, it is assumed that the structure of the F-pocket may restrict the length of binding peptides. The ability of HLA-B^*5101 binding peptides to stabilize the HLA-B^*5101 molecules was markedly lower than that of HLA-B^*3501 binding peptides to stabilize the HLA-B^*3501 molecules. It is known that HLA-B^*5101 is a slow assembling molecule, while HLA-B^*3501 assembles rapidly. The results imply that the slow assembling of HLA-B^*5101 molecules results from the low affinity of peptides to HLA-B^*5101 molecules. Received: 14 August 1996 / Revised: 8 October 1996     

Refined peptide HLA-B*3501 binding motif reveals differences in 9-mer to 11-mer peptide binding

 HLA-B^*3501 is associated with subacute thyroiditis and fast progression of AIDS. An important prerequisite to investigate the T-cell recognition of HLA-B^*3501-restricted antigens is the characterization of peptide-HLA-B^*3501 interactions. In this study, peptide-HLA-B^*3501 interactions were determined in quantitative peptide binding assays. The results were statistically analyzed to evaluate the influence of both anchor and nonanchor positions and the predictability of peptide binding. The binding data demonstrated that all anchor residues at position 2 and the C-terminus found in 9-mers functioned equally as anchors in 10-mers and 11-mers. These minimum requirements of peptide binding were refined by assessing positive and negative effects of nonanchor residues. Aliphatic hydrophobic residues at positions 3, 5, and 8 of 10-mers and position 3 of 11-mers significantly enhanced HLA-B^*3501 binding. Similar effects rendered aromatic, bulky residues, acidic or polar residues of 11-mers at position 1 as well as at positions 4, 8, and 10, respectively. Negative effects were observed for residues carrying positively charged side-chains at position 7 of 11-mers. The refined HLA-B^*3501 peptide binding motifs enhanced the identification of potential T-cell epitopes. The disparity between positive effects at the middle and C-terminal part (positions 5 – 8 and 10) of 11-mers and shorter peptides supports the extrusion of 11-mer residues at positions 5, 6, and 7, away from the HLA-B^*3501 binding cleft. Received: 29 May 1996 / Revised: 5 August 1996     

Molecular analysis of HLA-B39 subtypes

Serological studies have suggested the presence of a new HLA-B39 subtype (B39.2) in the Japanese population. To identify the new HLA-B39 subtype and compare it with an other HLA-B39 subtype (B39.1), the genes encoding HLA-B39.1 (B ^* 39013) and B39.2 (B ^* 3902) have been cloned from Japanese. We have sequenced these genes and completed the sequence of HLA-B39.1 (B ^*39011 ) gene from a Caucasian that was partially sequenced. Comparison of the sequence data revealed that B ^* 3902 and B ^* 39013 differ by three nucleotide substitutions which result in a two amino acids change at residues 63 and 67, while one silent substitution at codon 312 is found between B ^* 39011 and B ^* 39013. These results suggest that B ^* 3902 has evolved from B ^* 39013 rather than B ^* 39011.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers M94051 (HLA-B^*39013), M94052 (HLA-B^*39011), and M94053 (HLA-B^*3902).     

Large-scale production of class I bound peptides: assigning a signature to HLA-B*1501

 A peptide-based vaccine must be bound and presented by major histocompatibility complex class I molecules to elicit a CD8⁺ T-cell response. Because class I HLA molecules are highly polymorphic, it has yet to be established how well a vaccine peptide that stimulates one individual’s CD8⁺ cytotoxic T lymphocytes will be presented by a second individual’s different class I molecules. Therefore, to facilitate precise comparisons of class I peptide binding overlaps, we uniquely combined hollow-fiber bioreactors and mass spectrometry to assign precise peptide binding signatures to individual class I HLA molecules. In applying this strategy to HLA-B^*1501, we isolated milligram quantities of B^*1501-bound peptides and mapped them using mass spectrometry. Repeated analyses consistently assign the same peptide binding signature to B^*1501; the degree of peptide binding overlap between any two class I molecules can thus be determined through comparison of their peptide signatures. Received: 3 October 1996 / Revised: 20 November 1996     

Crucial role of N-terminal residue of binding peptides in recognition of the monoclonal antibody specific for the peptide-HLA-B5, -B35 complex

 The monoclonal antibody (mAb) 4D12 specific for the HLA-B5, -B35 cross-reacting group (CREG) bound to a fraction of HLA-B^*3501 and HLA-B^*5101 molecules carrying self-peptides. Analysis of the binding of mAb 4D12 to HLA-B^*3501 and -B^*5101 molecules pulsed with chemically synthesized peptides revealed that this mAb recognizes a restricted number of peptides and that P1 of the bound peptides critically influences its binding. The 4D12 mAb bound only to HLA-B^*3501 molecules carrying peptides with Asn, Asp, Glu, Ser, and Val at P1. Analysis using an HLA-B^*3501 crystallographic model suggested that 4D12 may recognize the side chain of the P1 residue that is pointing to the solvent. On the other hand, 4D12 bound only to HLA-B^*5101 molecules carrying peptides with Asn or Asp at P1, suggesting that the 4D12 epitope formed by Glu, Ser, or Val at P1 and the A-pocket was changed by the substitution of His for Tyr at residue 171 of HLA-B^*3501 molecules. This was confirmed by testing the binding of mAb 4D12 to HLA-B^*3501 mutant molecules at residue 171 carrying these peptides. These results together suggest that the conformation of the A-pocket and its hydrogen bound network with the P1 residue is also critical for the binding of mAb 4D12. The present study shows the molecular basis of the specificity of 4D12 for the peptide-HLA class I complex. Received: 19 June 1997 / Revised: 27 August 1997     

The peptide binding specificity of HLA-B27 subtypes

Five HLA-B27 subtypes, B^*2701, B^*2703, B^*2704, B^*2705, and B^*2706, were tested for direct binding with twenty-six synthetic nonapeptides carrying the primary anchor residue motifs (combination of amino residues at positions 2 and 9) relevant to B^*2705. The peptide sequences were derived from human HSP89, P53 and MBP. The alpha chains were immunospecifically isolated from LH (B ^* 2701), CH (B ^* 2703), WE1 (B ^* 2704), BTB (B ^* 2705), and LIE (B ^* 2706) cells and their peptide binding was measured by the HLA class I alpha chain refolding assay. The data obtained indicated that the B27 subtypes tested can bind a common set of peptides carrying several different anchor residue motifs. The motifs, R-K and R-R, reported for B^*2705 and a new motif H-R were accepted by B^*2703, B^*2704, and B^*2706, but not by B^*2701. However, other motifs, including known B^*2702 and/or B^*2705 motifs, R-H, R-L, R-A, and R-F, and a new motif found here, R-G, were apparently accepted by all B27 subtypes tested. The observed cross-peptide binding in the B27 subgroup is compatible with the so-called arthritogenic peptide hypothesis in the pathogenesis of ankylosing spondylitis.     

HLA class I binding of synthetic nonamer peptides carrying major anchor residue motifs of HLA-B27 (B*2705)-binding peptides

Eight nonamer peptides that comply with the major anchor residue motifs (the combination of amino acid residues at positions 2 and 9), R-K and R-R, of HLA-B27 (B^*2705)-binding peptides were synthesized and tested for their direct binding to HLA class I alpha chains by the HLA class I alpha chain refolding assay previously described. One was a known B27 (B^*2705)-binding heat shock protein peptide, HSP89 (201–209), and the other seven were derived from the sequence of wild-type P53, a human tumor suppressor protein. A total of 36 HLA class I allospecificities were tested. HSP89 (201–209) and two P53 peptides, P53 (362–370) and P53 (378–386), all possessing the motif R-K, bound strongly to B27 (B^*2705) alpha chains. A weak binding was seen for P53 (272–280) and P53 (334–342), both showing the motif R-R. Most of these B27-binding peptides were found to bind to A3 alpha chains as well. In addition, P53 (173–181) and P53 (334–342), both with the R-R motif, showed substantial binding with A31 alpha chains. All the peptides, carrying the motif R-K also showed weak binding with A31 alpha chains. The remaining two peptides, P53 (201–209) and P53 (282–290), with the motif R-R, did not show significant bininding with any of the alpha chains tested. This study demonstrates both the specificity of peptide binding to a given HLA allelic product and the occurence of cross-peptide-binding between the allelic products of different HLA loci. Correspondence to: N. Tanigaki.     

Position 45 influences the peptide binding motif of HLA-B*44:08

Position 45 represents a highly polymorphic residue within HLA class I alleles, which contacts the p2 position of bound peptides in 85% of the peptide–HLA structures analyzed, while the neighboring residues 41 and 46 are not involved in peptide binding. To investigate the influence of residue 45 at the functional level, we sequenced peptides eluted from recombinant HLA-B*44:08^{41Ala/45Met/46Ala} molecules and compared their features with known peptides from B*44:02^{41Thr/45Lys/46Glu}. While HLA-B*44:02 has an anchor motif of E at the p2 anchor position, HLA-B*44:08 exhibits Q and L as anchor motif. The 45^Met/Lys polymorphism contributes to the alteration in the peptide-binding motif and provides further evidence that mismatches at position 45 should be considered as nonpermissive in a transplantation setting.     

Assembly and intracellular trafficking of HLA-B*3501 and HLA-B*3503

Residue 116 of major histocompatibility complex (MHC) class I heavy chains is an important determinant of assembly, that can influence rates of ER-Golgi trafficking, binding to the transporter associated with antigen processing (TAP), tapasin dependence of assembly, and the efficiency and specificity of peptide binding. Here, we investigated assembly and peptide-binding differences between HLA-B*3501(S116) and HLA-B*3503(F116), two alleles differing only at position 116 of the MHC class I heavy chain, that are associated respectively with normal or rapid AIDS progression. A reduced intracellular maturation rate was observed for HLA-B*3503 in HIV-infected and uninfected cells, which correlated with enhanced binding of HLA-B*3503 to TAP. No significant differences in the intrinsic efficiency of in vitro peptide binding by HLA-B*3501 and HLA-B*3503 were measurable with several common peptides or peptide libraries, and both allotypes were relatively tapasin-independent for their assembly. However, thermostability differences between the two allotypes were measurable in a CD4⁺ T cell line. These findings suggest that compared to HLA-B*3501, a reduced intracellular peptide repertoire for HLA-B*3503 could contribute to its slower intracellular trafficking and stronger association with rapid AIDS progression.     

Generation of the HLA-B35, -B5, -B16, and B15 groups of alleles studied by intron 1 and 2 sequence analysis

 HLA-B is the most polymorphic of the major histocompatibility complex classical class I loci. This polymorphism is mainly in exons 2 and 3, which code for the molecule’s α1 and α2 domains and include the antigenic peptide binding site. Recent studies have indicated that not only exons but also the intron 2 region may be involved in the generation of certain HLA-B alleles such as B ^* 3906 and B ^* 1522. To study the degree of intron 2 participation and the mechanisms that generate polymorphism at the HLA-B locus, intron 1 and 2 sequences from the HLA-B35, -B5, -B16 and -B15 groups of alleles were obtained. A group-specific intronic polymorphism was found: namely, B ^* 5301 shows intron 1 and 2 sequences identical to those found in all B35 alleles studied. On the other hand, B ^* 5101 and B ^* 52012 show the same intron 1 and 2 sequences and their intron 1 is the same as that found in the B35 group. This suggests that B5 and B35 groups of alleles may have arisen from a common ancestor. All known B16 alleles show the same introns 1 and 2, with the exception of B ^* 39061 and B ^* 39062, and all B15 alleles also bear the same introns 1 and 2, with the exception of B ^* 1522. Variability at intron 1 is more restricted than at intron 2, and the use of intron 1 for HLA-B allele phylogenetic analysis is better for grouping alleles of a postulated common origin. In conclusion, there is a remarkable conservation of intronic sequences within related HLA-B alleles, which probably reflects a common origin and perhaps a selective force avoiding DNA changes. Intronic sequences are also potentially useful to design DNA typing strategies. Received: 11 March 1997 / Revised: 29 May 1997     

CD8+ T Cell Cross-Reactivity Profiles and HIV-1 Immune Escape towards an HLA-B35-Restricted Immunodominant Nef Epitope

Antigen cross-reactivity is an inbuilt feature of the T cell compartment. However, little is known about the flexibility of T cell recognition in the context of genetically variable pathogens such as HIV-1. In this study, we used a combinatorial library containing 24 billion octamer peptides to characterize the cross-reactivity profiles of CD8⁺ T cells specific for the immunodominant HIV-1 subtype B Nef epitope VY8 (VPLRPMTY) presented by HLA-B^*35∶01. In conjunction, we examined naturally occurring antigenic variations within the VY8 epitope. Sequence analysis of plasma viral RNA isolated from 336 HIV-1-infected individuals revealed variability at position (P) 3 and P8 of VY8; Phe at P8, but not Val at P3, was identified as an HLA-B^*35∶01-associated polymorphism. VY8-specific T cells generated from several different HIV-1-infected patients showed unique and clonotype-dependent cross-reactivity footprints. Nonetheless, all T cells recognized both the index Leu and mutant Val at P3 equally well. In contrast, competitive titration assays revealed that the Tyr to Phe substitution at P8 reduced T cell recognition by 50–130 fold despite intact peptide binding to HLA-B^*35∶01. These findings explain the preferential selection of Phe at the C-terminus of VY8 in HLA-B^*35∶01⁺ individuals and demonstrate that HIV-1 can exploit the limitations of T cell recognition in vivo.     

Rhesus macaque KIR bind human MHC class I with broad specificity and recognize HLA-C more effectively than HLA-A and HLA-B

Human killer cell immunoglobulin-like receptors (KIR) recognize A3/11, Bw4, C1, and C2 epitopes carried by mutually exclusive subsets of human leukocyte antigen (HLA)-A, -B, and -C allotypes. Chimpanzee and orangutan have counterparts to HLA-A, -B, and -C, and KIR that recognize the A3/11, Bw4, C1, and C2 epitopes, either individually or in combination. Because rhesus macaque has counterparts of HLA-A and -B, but not HLA-C, we expected that rhesus KIR would better recognize HLA-A and -B, than HLA-C. Comparison of the interactions of nine rhesus KIR3D with 95 HLA isoforms, showed the KIR have broad specificity for HLA-A, -B, and -C, but vary in avidity. Considering both the strength and breadth of reaction, HLA-C was the major target for rhesus KIR, followed by HLA-B, then HLA-A. Strong reactions with HLA-A were restricted to the minority of allotypes carrying the Bw4 epitope, whereas strong reactions with HLA-B partitioned between allotypes having and lacking Bw4. Contrasting to HLA-A and -B, every HLA-C allotype bound to the nine rhesus KIR. Sequence comparison of high- and low-binding HLA allotypes revealed the importance of polymorphism in the helix of the α₁ domain and the peptide-binding pockets. At peptide position 9, nonpolar residues favor binding to rhesus KIR, whereas charged residues do not. Contrary to expectation, rhesus KIR bind more effectively to HLA-C, than to HLA-A and -B. This property is consistent with major histocompatibility complex (MHC)-C having evolved in hominids to be a generally superior ligand for KIR than MHC-A and MHC-B.     

A new HLA-B44 subtype,B*4406, differing in exon 2

The name B ^*4406 was officially assigned by the WHO Nomenclature Committee in February 1995. This follows the agreed policy that, subject to the conditions stated in the most recent Nomenclature Report (Bodmer et al. 1994), names will be assigned to new sequences as they are identified. Lists of such new names will be published in the following WHO Nomenclature Report. The nucleotide sequences reported in this Papers have been submitted to the EMBL nucleotide sequence database and have been assigned the accession numbers X83400 (HLA-B promoter region), X83401 (exon 1), X83402 (exon 2), and X83403 (exon 3)     

Immunofixation for C2 typing: C2 allotypes in Spaniards in relation to HLA,Bf and C4

Summary C2 typing is performed by immunofixation with anti-C2 antiserum instead of by a hemolytic overlay. This method gives sharp band definition, is less cumbersome than the hemolytic overlay, gel files are easily made, and it also enables one to describe putative new nonhemolytic variants. C2 allele frequencies were studied in a sample of the normal Spanish population and were found to be similar to other Caucasoids. HLA-Bw62,-Cw3, and-DR4 were significantly associated with C2 B. Concordantly, the only C2^*B extended HLA haplotype found in family material was Bw62-Cw3-Bw6-(DR4)-Bf^*S-C2^*B-C4A^*3 B^*2-(GLO^*1). C4A^*4 B^*2 and C4A^*4 B^*4 are not found within the same haplotype together with C2^*B and Bw62 or Bw22 respectively, nor do other C2^*B haplotypes occur with common HLA-B alleles. These results may favour the hypothesis that the Bw62-C2^*B haplotype is produced by one mutation arising in the Bw62-C2^*C haplotype and that subsequent crossovers can explain other C2^*B haplotypes (including Bw22-C2^*B).