Fionnuala Williams

Frequency of cytokine polymorphisms in populations from Western Europe, Africa, Asia, the Middle East and South America

PCR-SSOP identification procedures for IL-2, IL-6, IL-10, TNF-alpha and TNF-beta cytokine polymorphisms have been developed. Application of the procedures to a range of diverse geographically distributed populations has identified ethnic differences within the groups studied. Five populations were investigated, Northern Ireland, South African Zulu, Omani, Singapore Chinese and Mexican Mestizos.

Analysis of the distribution of HLA-B alleles in populations from five continents

A two stage PCR-SSOP typing procedure, that permitted HLA-B allele assignment, was applied to DNA samples obtained from six diverse populations -Brazilian, Mexican (Series and Mestizos), Cuban (Caucasoid and Mulatto), South African Zulu, Omani, and Singapore Chinese. HLA-B allele frequencies and HLA-A/B two locus haplotype frequencies were compiled for each population.

The silent KIR3DP1 gene (CD158c) is transcribed and might encode a secreted receptor in a minority of humans, in whom the KIR3DP1, KIR2DL4 and KIR3DL1/KIR3DS1 genes are duplicated.

Killer‐cell Ig‐like receptors (KIR) are structurally and functionally diverse, and enable human NK cells to survey the expression of individual HLA class I molecules, often altered in infections and tumors. Multiple events of non‐reciprocal recombination have contributed to the rapid diversification of KIR. We show that ∼4.5% of the individuals of a Caucasoid population bear a recombinant allele of KIR3DP1, officially designed KIR3DP1*004, that associates tightly with gene duplications of KIR3DP1, KIR2DL4 and KIR3DL1/KIR3DS1. The KIR3DP1 gene is normally silent, but the recombinant allele carries a novel promoter sequence and, as a consequence, is transcribed in all tested individuals. Messenger RNA of KIR3DP1*004 is made up of six exons; of these, exons 1–5 are similar to, and spliced like, those encoding the leader peptide and Ig‐domains of KIR3D. By contrast, exon 6 is homologous to no other human KIR sequence, but only to possible homologs in chimpanzees and rhesus macaques, and encodes a short hydrophilic tail. The putative KIR3DP1*004 product, like those of the related genes LAIR‐2 and LILRA3/ILT6/LIR4, is predicted to be secreted to the extracellular medium rather than anchored to the cell membrane.

Study of age-association with cytokine gene polymorphisms in an aged Irish population

The release of cytokines is of crucial importance in the regulation of the type and magnitude of the immune response in the elderly. A number of studies have shown different levels of cytokine production in the elderly. In the present study, a range of polymorphisms were chosen within the genes of cytokines (IL-2, IL-6, IL-8, IL-10, IL-12 and IFN-gamma) that have been observed at different levels within the elderly and analysed for age-association. No association was observed for the polymorphic cytokine markers and the healthy aged Irish population (or with respect to gender) examined in this study. These findings would suggest that polymorphism of cytokine genes may not play as crucial a role in healthy ageing as previously believed.

Association of killer cell immunoglobulin-like receptor genes with Hodgkin's lymphoma in a familial study.

Background Epstein-Barr virus (EBV) is the major environmental factor associated with Hodgkins lymphoma (HL), a common lymphoma in young adults. Natural killer (NK) cells are key actors of the innate immune response against viruses. The regulation of NK cell function involves activating and inhibitory Killer cell Immunoglobulin-like receptors (KIRs), which are expressed in variable numbers on NK cells. Various viral and virus-related malignant disorders have been associated with the presence/absence of certain KIR genes in case/control studies. We investigated the role of the KIR cluster in HL in a family-based association study. Methodology We included 90 families with 90 HL index cases (age 16–35 years) and 255 first-degree relatives (parents and siblings). We developed a procedure for reconstructing full genotypic information (number of gene copies) at each KIR locus from the standard KIR gene content. Out of the 90 collected families, 84 were informative and suitable for further analysis. An association study was then carried out with specific family-based analysis methods on these 84 families. Principal Findings Five KIR genes in strong linkage disequilibrium were found significantly associated with HL. Refined haplotype analysis showed that the association was supported by a dominant protective effect of KIR3DS1 and/or KIR2DS1, both of which are activating receptors. The odds ratios for developing HL in subjects with at least one copy of KIR3DS1 or KIR2DS1 with respect to subjects with neither of these genes were 0.44[95% confidence interval 0.23–0.85] and 0.42[0.21–0.85], respectively. No significant association was found in a tentative replication case/control study of 68 HL cases (age 18–71 years). In the familial study, the protective effect of KIR3DS1/KIR2DS1 tended to be stronger in HL patients with detectable EBV in blood or tumour cells. Conclusions This work defines a template for family-based association studies based on full genotypic information for the KIR cluster, and provides the first evidence that activating KIRs can have a protective role in HL.

Frequency of HLA-B alleles in a caucasoid population determined by a two-stage PCR-SSOP typing strategy

High resolution PCR-SSOP typing methods for HLA-B identification have been established and applied to a Northern Ireland population, using large enough numbers to give dependable allele frequencies. The six systems, which operate independently of each other, are intended for use as secondary typing systems following HLA-B identification with a medium resolution PCR-SSOP technique.

Multiple copies of KIR 3DL/S1 and KIR 2DL4 genes identified in a number of individuals

Multiple copies of the killer immunoglobulin-like receptor gene, 3DL/S1, have been identified in certain individuals. Additionally, allele determination of the killer immunoglobulin-like receptor gene (KIR), 2DL4, has identified three alleles of this gene present in these same individuals. This event has been confirmed by isolating three distinct KIR2DL4 allele clones in each individual, which sequenced as the alleles identified by the allele identification technique. It is our assumption that an unequal crossover event has occurred between differing KIR haplotypes resulting in the duplication of the 2DL4, 3DS1/3DL1 genes on the newly formed haplotype(s).

Molecular diversity of the HLA-C gene identified in a caucasian population

A DNA typing procedure, based on a two stage polymerase chain reaction-sequence-specific oligonucleotide probe (PCR-SSOP) typing strategy, has been developed and applied to DNA from 1000 healthy individuals from the Northern Ireland region. The two-stage procedure involves human leukocyte antigen (HLA-C) identification through the use of a medium resolution PCR-SSOP system, followed by four secondary group specific PCR-SSOP systems, to enable allele resolution. The PCR-SSOP systems were designed for the identification of HLA-Cw alleles with possible discrimination within exons 2 and 3 of the HLA-C gene, i.e., HLA-Cw*01-Cw*16. PCR-SSP tests were designed for the resolution of HLA-Cw*17 and -Cw*18 alleles. The systems can also be used independently of each other if selective allele resolution is required. HLA-Cw allele frequencies occurring within the Northern Ireland population have been compiled, along with estimations of HLA-B/Cw haplotype frequencies.

Molecular typing of HLA class I and class II antigens in Indian kala-azar patients

Summary HLA has been shown to be associated with many diseases. To find out whether host genetic factors like the HLA are involved in susceptibility to kala‐azar (visceral leishmaniasis) in India, we formulated an association study with genetically related controls. All samples were typed by PCR SSOP (sequence specific oligonucleotide probes) for HLA class I (A and B) and class II (DR) antigens. The test of association we used was the transmission disequilibrium test (TDT). No significant evidence for association with any of the three HLA loci was obtained.

Immunogenetics and Life-Span

The major histocompatibility complex (MHC) is located in the region 9p216pter on the short arm of chromosome 6 and encompasses approx 4000 kilobases of genomic DNA. Contained within this complex are numerous genes with immune-related functions: notably the class I and class II human leukocyte antigens (HLA), tumor necrosis factor A and B, the complement genes, and genes that orchestrate the transport (TAP) and processing (LMP) of antigens for presentation. The HLA class I (HLA-A, HLA-B, HLA-C) and HLA class II (HLA-DR, HLA-DQ, HLA-DP) cell surface glycoproteins present antigenic peptides to CD8(+) and CD4(+) T cells, respectively, and play a central role in mediating the immune response. The HLA class I and class II genes display extreme degrees of polymorphism, making the MHC region the most polymorphic and densely populated area of the human genome. It is now well established that certain HLA specificities are strongly associated with numerous diseases, especially those with an autoimmune dimension, and confer resistance/susceptibility to certain infectious diseases. The possibility that HLA identity may have a genetic role in longevity in humans has long been suspected, spurred on by the importance of the HLA antigens in the immune response and data from studies in mice indicating that genes in the MHC region are associated with a significant effect on life-span. The results to date from these studies are confusing and contradictory, with no consistent association found as yet (1).