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The human T-cell antigen receptor (TCR) is the counter-receptor for the HLA/peptide complex displayed on the surface of antigen-presenting cells. It confers antigen specificity on T lymphocytes and therefore plays a central role in pathogen recognition and host response. The most frequently used form of the TCR is a heterodimer composed of variable α and β chains. We investigated allele frequencies for four variable-region gene segments of the β chain (2S1, 3S1, 8S3, and 15S1) in 146 Caucasians and 165 Africans. The results reveal significant unexpected differences between the two populations for allele frequencies, phenotypes, genotypes, and haplotypes. Among Caucasians, there are 43 phenotypes, whereas there are 31 among the Africans studied. There are 17 haplotypes in the Caucasian sample but only 10 in Africans. This loss of diversity is largely due to the high frequency of one haplotype in the African sample which represents 65% of the informative chromosomes. At least one copy of this haplotype is present in 90% of informative individuals. As a result, 29% of Africans are homozygous for the common haplotype. Less genetic diversity at TCRBV is unexpected, since Africans usually show greater genetic diversity than other ethnic groups. For example, there are approximately twice as many HLA haplotypes in Africans compared to Caucasians. Homozygosity is also unexpected because it reduces the number of TCR variants available to recognize HLA pathogen-derived peptide complexes. [ABSTRACT FROM AUTHOR]

Increased expression of epithelial cell-derived neutrophil-activating peptide (ENA-78) has been reported in several immune and inflammatory conditions suggesting its role in inflammatory response. We have identified two single nucleotide polymorphisms in the promoter and exon 2 of the ENA-78 gene by scanning the full length gene using DHPLC DNA fragment analysis and DNA sequencing. The polymorphism at position +398 (A/G from the first ATG codon) in exon 2 results in a synonymous substitution not resulting in an amino acid change. The promoter polymorphism was found at position -156 (C/G from the first ATG codon). An assay was designed for the detection of the polymorphisms using SNapshot ddNTP primer extension, followed by capillary electrophoresis (ABI 3100). Allele and genotype frequencies for the promoter -156 polymorphism are presented for 107 healthy Spanish and 54 UK Caucasians. Frequencies for the exon 2 polymorphism are also presented for 63 UK Caucasians. [ABSTRACT FROM AUTHOR]