%0 Journal Article
%T Differences between naive and memory T cell phenotype in Malawian and UK adolescents: a role for Cytomegalovirus?
%A Anne Ben-Smith
%A Patricia Gorak-Stolinska
%A Sian Floyd
%A Rosemary E Weir
%A Maeve K Lalor
%A Hazzie Mvula
%A Amelia C Crampin
%A Diana Wallace
%A Peter CL Beverley
%A Paul EM Fine
%A Hazel M Dockrell
%J BMC Infectious Diseases
%D 2008
%I BioMed Central
%R 10.1186/1471-2334-8-139
%X Venous blood from HIV-negative adolescents and blood from the umbilical cords of babies, born to HIV-negative women, post-delivery was collected and analysed using flow cytometry. T cell phenotype was determined from peripheral blood lymphocytes and cytomegalovirus (CMV) seropositivity was assessed by ELISA in adolescents.HIV-negative Malawian adolescents were shown to have a lower percentage of na£żve T cells (CD45RO-CD62Lhi CD11alo), a higher proportion of memory T cells and a higher percentage of CD28- memory (CD28-CD45RO+) T cells compared to age-matched UK adolescents. Malawian adolescents also had a lower percentage of central memory (CD45RA-CCR7+) T cells and a higher percentage of stable memory (CD45RA+CCR7-) T cells than UK adolescents. All of the adolescents tested in Malawi were seropositive for CMV (59/59), compared to 21/58 (36%) of UK adolescents. CMV seropositivity in the UK was associated with a reduced percentage of na£żve T cells and an increased percentage of CD28- memory T cells in the periphery. No differences in the proportions of na£żve and memory T cell populations were observed in cord blood samples from the two sites.It is likely that these differences between Malawian and UK adolescents reflect a greater natural exposure to various infections, including CMV, in the African environment and may imply differences in the ability of these populations to induce and maintain immunological memory to vaccines and natural infections.The immune system maintains both na£żve and memory T cells, so that individuals can mount an immune response to a variety of new antigens while keeping appropriate levels of memory T cells that recognise previously encountered pathogens. Na£żve and memory T cells can most simply be characterised by the reciprocal expression of the CD45RA or CD45RO isoforms [1,2]. In general, na£żve (CD45RA+/CD45RO-) T cells represent the most homogeneous pool of T cells as they lack most effector functions. These cells migrate through secondar
%U http://www.biomedcentral.com/1471-2334/8/139