Physiological ageing is accompanied by decline in immune system function and immune alteration during ageing increases susceptibility to infections. We retrospectively analysed the data for complete blood count (CBC) and lymphocyte subsets from infant to elderly age groups to determine changes during ageing. Data from dual-platform flow cytometry and CBC were analysed to determine the percentage (%) and absolute cell counts (Abs) of peripheral blood lymphocyte subsets (CD3, CD4, CD8, CD19 and CD56+16+ cells) in infants (1 month to 1 year), children (1 year to 6 years), adolescents (12 years to 18 years), adults (21 years to 50) and elderly (70 years to 92 years). Differences in plasma cytokine levels in adults and elderly were also analysed using Randox system. Comparisons among age groups from infants through adults revealed progressive declines in the percentage of total lymphocytes and absolute numbers of T and B cells. The NK cells declined from infancy to adulthood but increased in elderly participants. The percentages of T cells increased with age from infant to adulthood and then declined. Pro-inflammatory cytokines, TNF-a and IL-6, were higher in elderly people compared to adults. The elderly group had significantly higher levels of monocyte chemoattractant protein-1 (MCP-1) and lower levels of epidermal growth factor (EGF) compared to adults. Our findings confirm and extend earlier reports on age-related changes in lymphocyte subpopulations and data generated from this study is useful for clinicians and researchers, patient management in various age groups for the interpretation of disease-related changes, as well as therapy-dependent alterations.

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BackgroundThe influence of tobacco smoking on the immune system of HIV infected individuals is largely unknown. We investigated the impact of tobacco smoking on immune activation, microbial translocation, immune exhaustion and T-cell function in HIV infected individuals.MethodHIV infected smokers and non-smokers (n = 25 each) with documented viral suppression on combination antiretroviral therapy and HIV uninfected smokers and non-smokers (n = 15 each) were enrolled. Markers of immune activation (CD38 and HLA-DR) and immune exhaustion (PD1, Tim3 and CTLA4) were analyzed in peripheral blood mononuclear cells (PBMCs) by flow cytometry. Plasma markers of microbial translocation (soluble-CD14 - sCD14 and lipopolysaccharide - LPS) were measured. Antigen specific functions of CD4+ and CD8+ T-cells were measured, by flow cytometry, in PBMCs after 6 hours stimulation with Cytomegalovirus, Epstein-Barr virus and Influenza Virus (CEF) peptide pool.ResultsCompared to non-smokers, smokers of HIV infected and uninfected groups showed significantly higher CD4+ and CD8+ T-cell activation with increased frequencies of CD38+HLA-DR+ cells with a higher magnitude in HIV infected smokers. Expressions of immune exhaustion markers (PD1, Tim3 and CTLA4) either alone or in combinations were significantly higher in smokers, especially on CD4+ T-cells. Compared to HIV uninfected non-smokers, microbial translocation (sCD14 and LPS) was higher in smokers of both groups and directly correlated with CD4+ and CD8+ T-cell activation. Antigen specific T-cell function showed significantly lower cytokine response of CD4+ and CD8+ T-cells to CEF peptide-pool stimulation in smokers of both HIV infected and uninfected groups.ConclusionsOur results suggest that smoking and HIV infection independently influence T-cell immune activation and function and together they present the worst immune profile. Since smoking is widespread among HIV infected individuals, studies are warranted to further evaluate the cumulative effect of smoking on impairment of the immune system and accelerated disease progression.

Natural killer (NK) cells are not only important in first line defence against viral and bacterial infections, but also in immune surveillance of malignant cells and thus NK cell cytotoxicity is primary indicator of immune function. Although chromium release assay is recognized as ‘gold standard’ for measuring NK cell activity, it has disadvantages like use of radioactive compounds, poor loading and high spontaneous release. It is difficult to perform this assay in clinical laboratory because of difficulties with disposal of radioactive waste and standardization problems. We describe a flow cytometry‐based assay for the measurement of NK cell activity by incorporating fluorescent dye, DiO, into membranes of target cells. NK cell activity was measured at baseline, 1 and 4 weeks follow‐up in 20 normal healthy individuals on a dietary supplement immunomodulator to enhance NK cell function. Mean baseline NK cell activity percentage (21.5; SD = 9.3) increased significantly to a maximum level at 1 week (31.3%; SD = 7.9; P = 0.007) and then returned to baseline level at 4 weeks (21.5; SD = 8.3). An important feature of flow cytometry‐based assays is its ability to discriminate effector cells from target cells, and potential for explaining molecular interactions underlying target cell lysis. Under clinical settings, this assay will be of interest for frequently monitoring immunological status of patients on treatment for various diseases that affect their immune status. The assay is easy to perform without using radioactive material and thus could become a tool for monitoring pathogenesis and immune reconstitution.

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