Lymphocytes in ASCT and HIV Figure 2. CD8+ T cell maturation patterns lymphocytes in ASCT recipients (ASCT), in HIV-infected patients (HIV) and healthy controls (HC). The percentage of na¨ıve CD8+ T cells (CD45RA+CCR7+) (A), central memory (CD45RA2CCR7+) (B), effector memory (CD45RA2CCR72) (C) and effector cells (CD45RA+CCR72) (D) were compared in the groups. Higher levels of na¨ıve CD8+ T-cells were observed in ASCT recipients compared to HIV+ patients. Whereas in HIV positive patients effector memory CD8+ T cells were the predominant memory phenotype, in ASCT recipients significantly higher levels of CD45RA+CCR72 effector CD8+ cells were evidenced. Each central bar represents the median value and each box corresponds to the 25th through 75th percentile (interquartile) range. doi:10.1371/journal.pone.0003616.g002 between CM/EM, EM/TD, CM/TD CD4+ subpopulations in ASCT patients, thus confirming the skewed representation of repopulating memory CD4+ T cells. In stark contrast, the CD45RA2CCR72CD8+ and CD45RA+CCR72CD8+ ratio was significantly higher in HIV+ patients compared to ASCT recipients, who displayed values similar to healthy controls (ASCT 1.83, HIV 5.77, HC 0.97, p,0.05 for HIV versus ASCT and HC). This observation underlines the over-representation of pre-terminally differentiated CD8+ T cells and the simultaneously lower levels of terminally differentiated CD8+ T cells in HIV population (Fig. 3). Cytokine CD4+ production is impaired in both ASCT recipients and HIV-infected patients To determine whether the relevant phenotypic characteristics are associated with selective defects in cytokine production in ASCT recipients compared to HIV-infected subjects, we tested the capacity of CD4+ T cells to produce IL-2 and IFN-c in response to superantigen stimulation (fig. 4A). Profound impairment in IL-2 and IFN-c production after SEB stimulation was found in both group of patients with respect to age-matched healthy controls (IL- 2+/CD4+ ASCT 1.18%, HIV 0.4%, HC 5.28%, p,0.05 for HC versus ASCT and HIV; IFN-c+/CD4+ ASCT 0.96%, HIV 1.2%, HC 2.59%, p = ns).These observations suggest that CD4+ T cells activated via T-cell receptor stimulation are dramatically weak- ened in their capacity to produce IL-2 and IFN-c, both in ASCT recipients and in HIV disease. Cytokine CD8+ production is observed in ASCT recipients but not in HIV-infected patients In ASCT recipients, cytokine expression analysis for CD8+ T- cells produced a very different picture with respect to the HIV population (fig. 4B). Compared to HIV-infected patients, in fact, ASCT recipients showed significantly higher levels of TNF-a and IFN-c producing CD8+ T cells (2.27% versus 0.3% and 2.00% versus 0.35% respectively, p,0.05). Moreover, differences were detected in cytokine production after SEB stimulation: CD8+ lymphocytes from ASCT recipients displayed significantly higher production of TNFa than those of HIV-infected patients (2.27% versus 0.45%, p,0.05) reaching levels similar to healthy controls PLoS ONE | www.plosone.org 4 October 2008 | Volume 3 | Issue 10 | e3616