Differences between naive and memory T cell phenotype in Malawian and UK adolescents: a role for Cytomegalovirus?

Background: Differences in degree of environmental exposure to antigens in early life have been hypothesized to lead to differences in immune status in individuals from different populations, which may have implications for immune responses in later years.Methods: 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.Results: HIV-negative Malawian adolescents were shown to have a lower percentage of naive T cells (CD45RO-CD62L(hi)CD11a(lo)), 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 naive T cells and an increased percentage of CD28- memory T cells in the periphery. No differences in the proportions of naive and memory T cell populations were observed in cord blood samples from the two sites.Conclusion: 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

Telomere erosion in memory T cells induced by telomerase inhibition at the site of antigenic challenge in vivo

This work was funded by grants from the Biotechnology and Biological Sciences Research Council Experimental Research on Aging Initiative, Research Into Aging, The Sir Jules Thorne Research Trust, and The Hayward Foundation and Dermatrust

Modelling the Influence of Foot-and-Mouth Disease Vaccine Antigen Stability and Dose on the Bovine Immune Response

Foot and mouth disease virus causes a livestock disease of significant global socio-economic importance. Advances in its control and eradication depend critically on improvements in vaccine efficacy, which can be best achieved by better understanding the complex within-host immunodynamic response to inoculation. We present a detailed and empirically parametrised dynamical mathematical model of the hypothesised immune response in cattle, and explore its behaviour with reference to a variety of experimental observations relating to foot and mouth immunology. The model system is able to qualitatively account for the observed responses during in-vivo experiments, and we use it to gain insight into the incompletely understood effect of single and repeat inoculations of differing dosage using vaccine formulations of different structural stability

Is T-cell memory maintained by crossreactive stimulation?

Whether or not T- and B-cell memory is antigen driven remains unresolved. Recent studies indicate that, in humans, naive and memory T cells can be distinguished by their expression of different CD45 isoforms. Extensive phenotypic analysis of naive and memory T cells shows that the latter express greater amounts of several adhesion molecules as well as low levels of several antigens indicative of activation. These features suggest to Peter Beverley that memory T cells may be more readily activated and that memory may be maintained by crossreactive restimulation. © 1990

Interferon, β-2-microglobulin and immunoselection in the pathway to malignancy. A blinkered view from Nag's Head Yard

Recent clinical studies suggest that benign tumour cells express MHC class-I antigens while malignant cells with the same tissue origin do not. Interferons induce normal cells to increase the expression of class-I antigens but Arnold Sanderson and Peter Beverley argue here that malignant cells may not respond in this way. As a result, they may lack the antigens that would make them vulnerable to immune mechanisms dependent on T cells which recognize class-I self-MHC antigens. © 1983

Immunological intervention with monoclonal antibodies

A recent workshop held in the Bavarian alps considered the possibilities for immunological intervention with monoclonal antibodies. While at present the benefits of most attempts to use monoclonal antibodies in vivo in man are uncertain, in vitro and animal experiments have yielded enough positive results to encourage further efforts. Immediate dramatic effects are not to be expected because as one participant noted, we are still at an early stage in the use of monoclonal antibodies as therapeutic agents