Studies on IgE, IgG1 and IgG4 response patterns to Glycans and their implications on allergies in a selection of Ghanaian school children from urban high, urban low and rural areas

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November, 2016
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Recent findings indicate many individuals in developing countries as not manifesting hypersensitivity reactions upon sensitization, due partly to the presence of cross-reactive Immunoglobulin E antibodies (IgEs) which recognize oligosaccharide epitopes with α3–fucose and β2-xylose core modifications; or galactose–α–1,3–galactose (α-gal). IgE, IgG1 and IgG4 response profiles were studied in a selection of pupils from urban and rural areas to printed glycan epitopes to compare glycan-associated antibody responses at different socio-economic levels in the Greater Accra Region, testing the hypothesis that cross-reactive antibody activity was more prevalent in the rural than urban areas. Out of an initial urban-rural recruitment of 2,331 participants who provided urine, stool, and blood samples, 20 each from an urban high (UH), urban low (UL), and rural (R) school, were randomly selected and their serum samples processed via a synthetic glycan microarray. With the ImmunoCAP, IgE titres in the 60 Ghanaian samples to a panel of allergens including bromelain, and α-gal were measured. For comparison, IgE, IgG1, and IgG4 response patterns to glycans were characterized for a selection of Europeans (N = 5) via the glycan microarray. Results indicated an area-associated trend, with higher IgE responses observed in the R than the urban areas towards α3-fucosylated N-glycans. Also, strong associations between S. haematobium positivity and IgE signal intensities to β2-xylose were observed. Glycan recognition patterns were similar for IgE and IgG1 across the 128 printed glycans, but differed for IgG4 which showed no clear pattern. High IgE and IgG1 signal responses were observed for the selected European subjects to be directed against core structures with either an α3-fucose, a β2-xylose, or both. IgG4 signal intensities were at threshold magnitudes, and did not yield any discernible pattern.
A Thesis submitted to the Department of Clinical Microbiology, School of Medical Sciences, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Clinical Microbiology, School of Medical Sciences.