Immunogenetics

Swarbrick, Peter; Schwaiger, Franz-Werner; Epplen, Jorg; Buchan, Glen; Griffin, J.; Crawford, Allan

doi: 10.1007/BF00164981pmid: 7797262

The expressed major histocompatibility complex (Mhc) class II DRB genes of 50 unrelated deer were examined by reverse transcription polymerase chain reaction, cloning, and sequencing of DRB exon 2. Deer, like other mammals, have at least one highly polymorphic Mhc class II DRB gene. Thirty-four different sequences were identified. Most of the variation in amino acid composition occurred at positions that have been shown to form the peptide binding site (PBS). Eighteen deer-specific substitutions were found, 11 of these occurred in the PBS. Significantly higher rates of replacement substitutions than silent substitutions were found in the deer sequences, indicating strong positive selection pressure for diversity in DRB sequences. Between one and four DRB sequences were found per deer. Inheritance of these sequences in pedigrees showed Mendelian segregation with up to two expressed DRB genes per haplotype. Sheep are the only other ruminant in which the presence of more than one expressed DRB gene has been demonstrated. Phylogenetic trees were constructed in an attempt to assign the deer DRB sequences to specific loci, but no clear segregation of the DRB sequences for different loci was found. It would seem likely that sequence exchange between the loci has occurred. As has been shown in other species, the α-helix and β-sheet regions of exon 2 appeared to have different evolutionary histories.

Moss, Paul; Bell, John

doi: 10.1007/BF00164982pmid: 7797263

Although the three-dimensional structure of the T-cell receptor (TCR) has not yet been determined, several groups have proposed that the outline structure of the TCR will closely resemble that of immunoglobulin (Ig). Hyper-variable regions can be identified within the TCR variable (V) domains, and by analogy to similar regions in the Ig molecule which together form the antigen combining site these have been termed the complementarity determining regions (CDR) 1, 2, and 3. By far the greatest extent of variability occurs at CDR3 and this has led to the proposal that CDR3 is involved in interaction with the peptide bound within the cleft of a major histocompatibility complex (MHC) molecule. We have cloned and sequenced the CDR3 region of several hundred human TCRA and TCRB transcripts from different T-cell populations and studied the amino acid usage in this region. Results show that the average lenght of the CDR3 region is 10 amino acids with less variation in length than is seen for the Ig heavy chain. There is no difference in CDR3 length between fetal and adult T cells or between CD4 and CD8 populations. The pattern of amino acid usage in the CDR3 region is dissimilar between TCRA and TCRB transcripts. In particular there is a predominance of charged and polar residues in the region of the TCRA transcript thought to interact with peptide. These data provide information on the general pattern of CDR3 length and composition for both TCRA and TCRB.

Garber, Theodore; Butler, Lesley; Trachtenberg, Elizabeth; Erlich, Henry; Rickards, Olga; Stefano, Gianfranco; Watkins, David

doi: 10.1007/BF00164983pmid: 7797264

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.

Woodward, Elaine; Monaco, John

doi: 10.1007/BF00164984pmid: 7797265

The proteasome subunit DELTA is unusually closely related to the major histocompatibility complex (MHC)-linked proteasome subunit, LMP2. The sequence of a mouse cDNA for DELTA confirms that this 22 100 M r proteasome subunit is highly conserved across species. Sequence analysis of the mouse gene encoding DELTA, designated Lmp19, indicates that it consists of six exons and five introns, similar to the Lmp2 gene. The 5′ upstream region lacks a TATA regulatory sequence, which is also absent from proteasome genes isolated from Drosophila. BXD recombinant inbred (RI) mice were used to map the potential chromosomal location of Lmp19, and revealed that the DELTA subunit has related sequences present on two different mouse chromosomes, chromosomes 1 and 11. Typing of 89 progeny from a C57BL/6J X Mus spretus DNA backcross panel (BSS) confirmed the chromosome 1 assignment. Southern hybridization with a polymerase chain reaction-generated Lmp19 intron 2-specific probe indicates that the Lmp19 genomic clone corresponds to the sequence on chromosome 11, and further suggests that the chromosome 1 copy represents a processed pseudogene (Lmp19-ps1).

Gonzalez-Gay, Miguel; Zanelli, Eric; Krco, Christopher; Nabozny, Gerald; Hanson, Julie; Griffiths, Marie; Luthra, Harvinder; David, Chella

doi: 10.1007/BF00164985pmid: 7797266

Collagen-induced arthritis (CIA) is an animal model of auto immune polyarthritis, sharing similarities with rheumatoid arthritis (RA). Paradoxally, susceptibility to mouse CIA is controlled by the H2A loci (DQ homologous) while RA is linked to HLA.DR genes (H2E homologous). We recently showed that the Eβd molecule prevents CIA development in susceptible H2 q mice. We addressed the question of whether H2Eb polymorphism will influence CIA incidence as HLA.DRB1 polymorphism does in RA. In F1 mice, only H2Ebd and H2Ebs molecules showed protection. Using recombinant B10.RDD (Eb d/b) mice, we found that CIA protection was mediated by the first domain of the Eβd molecule. Using peptides covering the third hypervariable region of the Eβ chain, we found a perfect correlation between presentation of Eβ peptides by the H2Aq molecule and protection on CIA. Therefore, the mechanism by which H2Eb protects against CIA seems to rely on the affinity of Eβ peptides for the H2Aq molecule.

Dangel, Andrew; Baker, Bradley; Mendoza, Anna; Yu, C.

doi: 10.1007/BF00164986pmid: 7797267

The complement component C4 genes of Old World primates exhibit a long/short dichotomous size variation, except that chimpanzee and gorilla only contain short C4 genes. In human it has been shown that the long C4 gene is attributed to the integration of an endogenous retrovirus, HERV-K(C4), into intron 9. This 6.36 kilobase retroviral element is absent in short C4 genes. Here it is shown that the homologous endogenous retrovirus, ERV-K(C4), is present precisely at the same position in the long C4 gene of orangutan and African green monkey. Determination of the short C4 gene intron 9 sequences from human, three apes, two Old World monkeys, and a New World monkey allowed the establishment of consistent phylogenetic trees for primates, which favors a chimpanzee-gorilla clade. The 5′ long terminal repeats (LTR) and 3′ LTR of ERV-K(C4) in long C4 genes of human, orangutan, and African green monkey have similar sequence divergence values of 9.1%–10.5%. These values are more than five-fold higher than the sequence divergence of the homologous intron 9 sequences between the long and short C4 genes in higher primates. The latter is probably a result of homogenization or concerted evolution. We suggest that the 5′ LTR and 3′ LTR of an endogenous retrovirus can serve as a reliable reference point or a molecular clock for studies of gene duplication and gene evolution. This is because the 5′/3′ LTR sequences were identical at the time of retroviral integration and evolved independently of each other afterwards. Our data provides strong evidence for the short C4 gene being the ancestral form in primates, trans-species evolution, and the “slow-down” phenomenon of the sequence divergence in great apes.

Breiteneder, Heimo; Scheiner, Otto; Hajek, Roswitha; Hulla, Wolfgang; Hüttinger, Robert; Fischer, Gottfried; Kraft, Dietrich; Ebner, Christof

doi: 10.1007/BF00164987pmid: 7797268

T-cell clones (TCC) were raised from the peripheral blood of patients suffering from tree pollen allergy. All TCC were restricted by HLA-DR molecules. In order to investigate possible intervention targets in Type I allergic diseases, we examined T-cell receptor (TCR) α and β chain nucleotide sequences of five allergen-reactive human CD4+ TCC specific for a C-terminal epitope (BV 144) of Bet v 1, the major birch pollen allergen. Proliferation assays using synthetic peptides revealed the 10-mer LRAVESYLLA as minimal epitope for three TCC; two TCC also displayed reactivity with the nonapeptide LRAVESYLL. Two TCC expressed TCRBV2S3, all other BV144-specific TCC used diverse TCRAV and TCRBV gene segments. Moreover, the junctional regions encoding the third complementary determining regions (CDR3) of the TCR showed a striking heterogeneity in length and amino acid composition. Nevertheless, all TCC showed an arginine residue in the N-terminal region of their TCRBV CDR3 loops. Therefore, therapeutical strategies aimed at the clonal deletion of allergen-specific T-cell clones, providing help for IgE synthesis, will not be feasible. Our results cast a doubt on the theory that the CDR3 exclusively provides the primary contact with the peptide bound in the major histocompatibility (MHC) groove, and suggest additional interaction with MHC class II.

Kingsmore, Stephen; Souryal, Carolyn; Watson, Mark; Patel, Dhavalkumar; Seldin, Michael

doi: 10.1007/BF00164988pmid: 7797269

By virtue of sequence similarity, the genes encoding CD2, CD48, CD58, and Ly-9 have been assigned to a distinct subset within the immunoglobulin superfamily. Previous gene mapping studies in human and mouse have suggested that CD2, CD48, and CD58 arose by gene duplication. Here we show the gene encoding Ly-9 to be located adjacent to CD48 and the Na,K-ATPase α2 subunit gene on human and mouse chromosome 1. The proximity in human and mouse genomes of the genes encoding CD2, CD58, and the Na,K-ATPase α1 subunit, and of the Ly-9, CD48, and the Na,K-ATPase α2 subunit genes may be explained by the occurence of two, successive duplication events during vertebrate evolution, and suggest that Ly-9 may also participate in adhesion reactions between T lymphocytes and accessory cells by homophilic interaction.

Wang, Chyung-Ru; Lambracht, Doris; Wonigeit, Kurt; Howard, Jonathan; Fischer Lindahl, Kirsten

doi: 10.1007/BF00164989pmid: 7797270

Wittzell, Håkan; Schantz, Torbjörn; Zoorob, Rima; Auffray, Charles

doi: 10.1007/BF00164990pmid: 7797271