Prevalent role of TCR alpha-chain in the selection of the preimmune repertoire specific for a human tumor-associated self-antigen.

The specificity of recognition of pMHC complexes by T lymphocytes is determined by the V regions of the TCR alpha- and beta-chains. Recent experimental evidence has suggested that Ag-specific TCR repertoires may exhibit a more V alpha- than V beta-restricted usage. Whether V alpha usage is narrowed during immune responses to Ag or if, on the contrary, restricted V alpha usage is already defined at the early stages of TCR repertoire selection, however, has remained unexplored. Here, we analyzed V and CDR3 TCR regions of single circulating naive T cells specifically detected ex vivo and isolated with HLA-A2/melan-A peptide multimers. Similarly to what was previously observed for melan-A-specific Ag-experienced T cells, we found a relatively wide V beta usage, but a preferential V alpha 2.1 usage. Restricted V alpha 2.1 usage was also found among single CD8(+) A2/melan-A multimer(+) thymocytes, indicating that V alpha-restricted selection takes place in the thymus. V alpha 2.1 usage, however, was independent from functional avidity of Ag recognition. Thus, interaction of the pMHC complex with selected V alpha-chains contributes to set the broad Ag specificity, as underlined by preferential binding of A2/melan-A multimers to V alpha 2.1-bearing TCRs, whereas functional outcomes result from the sum of these with other interactions between pMHC complex and TCR

Prevalence of human immunodeficiency virus and hepatitis C virus among French prison inmates in 2010: a challenge for public health policy

International audienceWe evaluated prevalence of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) among prison inmates in France in 2010, in a cross-sectional single-day study based on a two-stage design. Sampling favoured larger establishments and included all types of prisons. Establishments were stratified by geographical region. Estimates were adjusted by post-stratification of the total population of inmates in France. From 60,975 inmates in all 188 prisons on the sampling day, 2,154 were selected from 27 prisons, and 1,876 questionnaires completed. HIV prevalence was estimated at 2.0% (95% confidence interval (CI): 0.9-4.2), 2.6% (95% CI: 0.7-8.8) in women and 2.0% (95% CI: 0.9-4.3) in men; 75% of inmates were receiving treatment for HIV. HCV prevalence was estimated at 4.8% (95% CI: 3.5-6.5) and was higher for women (11.8%; 95% CI: 8.5-16.1) than men (4.5%; 95% CI: 3.3-6.3). Almost half of HCV-infected inmates had chronic hepatitis C and 44% were receiving or had received treatment. HIV and HCV prevalence was six times higher than in the general population, and 2.5% of inmates had viraemic hepatitis C. The moment of incarceration provides an ideal opportunity for testing and treating, limiting spread of HCV and improving patients' prognosis