Proportions of CD41 memory T cells are altered in individuals chronically infected with Schistosoma haematobium

Characterisation of protective helminth acquired immunity in humans or experimental models has focused on effector responses with little work conducted on memory responses. Here we show for the first time, that human helminth infection is associated with altered proportions of the CD41 memory T cells, with an associated alteration of TH1 responses. The reduced CD41memory T cell proportions are associated with a significantly lower ratio of schistosome-specific IgE/IgG4 (marker for resistance to infection/re-infection) in uninfected older people. Helminth infection does not affect the CD81memory T cell pool. Furthermore, we show for the first time in a helminth infection that the CD41 memory T cell proportions decline following curative anti-helminthic treatment despite increased CD41 memory cell replication. Reduced accumulation of the CD41 memory T cells in schistosome-infected people has implications for the development of natural or vaccine induced schistosome-specific protective immunity as well as for unrelated pathogens.,World Health Organisation (Grant no RPC264), the Wellcome Trust (Grant no WT082028MA) and by Thrasher Research Fund