Showing papers by "Anthony Nolan published in 1998"

Mutation detection and typing of polymorphic loci through double-strand conformation analysis.

Abstract: Variations, such as nucleotide substitutions, deletions and insertions, within genes can affect the function of the gene product and in some cases be deleterious. Screening for known allelic variation is important for determining disease and gene associations1. Techniques which target specific mutations such as restriction enzyme polymorphism and oligonucleotide probe or PCR primer reactivity are useful for the detection of specific mutations, but these techniques are not generally effective for the identification of new mutations. Approaches for measuring changes in DNA conformation have been developed, based on the principle that DNA fragments which differ in nucleotide composition exhibit different mobilities after separation by polyacrylamide gel electrophoresis (PAGE; refs 2,3). Here we describe a conformation-based mutation detection system, double-strand conformation analysis (DSCA), which provides a simple means to detect genetic variants and to type complex polymorphic loci. We demonstrate the application of DSCA to detect genetic polymorphisms such as a single-nucleotide difference within DNA fragments of up to 979 base pairs in length. We present the application of DSCA in detecting four different mutations in the cystic fibrosis gene (CFTR) and 131 different alleles encoded by HLA class I genes.

Hepatitis B third-generation vaccines: improved response and conventional vaccine non-response--evidence for genetic basis in humans

Abstract: The lack of response to hepatitis B vaccination remains a problem for those individuals directly at risk of hepatitis B infection, particularly those who work in the health care industry. The factors associated with non-response to hepatitis B vaccination have been investigated in 86 non-responder health care workers who had received multiple 'S' vaccinations without sustained production of anti-HBs. This group received a recently developed hepatitis B vaccine, Hepagene, which included proteins derived from the envelope region of HBV, not present in currently licensed vaccines. The pre-S1 and pre-S2 proteins were included in Hepagene in order to circumvent anti-HBs non-responsiveness which had previously been demonstrated in the inbred mouse model. The inclusion of these additional proteins in Hepagene enabled some seroconverion, from non-responder to responder; however, a proportion of the vaccinees remained non-responders and the reasons for this have been investigated here, with reference to HLA alleles and the demographic predisposition. Here the mechanisms that underlie hepatitis B vaccine non-response have considered the distribution of HLA alleles, age, sex, height and weight in addition to the T-cell responses to Hepagene derived antigens.

Fetal natural killer cell function is suppressed.

Abstract: Previous studies have reported reduced natural killer (NK) cell activity in cord blood (CB) compared with adult blood mononuclear cell populations. Using a non-radioactive killing assay, we have verified these findings suggesting that either the fetal NK cell function is suppressed or that these cells are functionally immature. We have shown that CB NK cells are functional, since activating them with cytokines known to activate adult NK cells [interleukin-2 (IL-2), IL-12 and IL-15] increased activation. However, resting the cells, which enhanced adult NK cell activity (P < 0.01), had no effect on fetal NK cells (P = 0.2). These results suggested that fetal NK cells have the capacity to kill, but this is suppressed in vitro. This hypothesis was strengthened by our observation that eight of nine CB mononuclear cell populations had their NK activity restored by freeze-thawing, whereas four of five adult peripheral blood mononuclear cells had a reduced killing ability on freeze-thawing. Freeze-thawing removes a population of cells that suppresses CB NK cell function. To determine which was the case we performed extensive phenotypic analysis of the CB populations pre- and post-freezing and found that the percentage of the CD3- CD56+ population within CB increased significantly (P < 0.0005 by paired t-test) with freezing, whereas freeze-thawing had no effect on this population within a normal adult peripheral blood mononuclear cell population. Our data suggest that within CB there is a population of cells, as yet undefined, which may be inhibiting NK cell function. This report therefore shows clear differences between NK cells within the adult periphery and in CB, and may lead to a better understanding of events occurring in vivo.