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Impact of blood processing variations on natural killer cell frequency, activation, chemokine receptor expression and function.

ABSTRACT: Understanding the role of natural killer (NK) cells in human disease pathogenesis is crucial and necessitates study of patient samples directly ex vivo. Manipulation of whole blood by density gradient centrifugation or delays in sample processing due to shipping, however, may lead to artifactual changes in immune response measures. Here, we assessed the impact of density gradient centrifugation and delayed processing of both whole blood and peripheral blood mononuclear cells (PBMC) at multiple timepoints (2-24 h) on flow cytometric measures of NK cell frequency, activation status, chemokine receptor expression, and effector functions. We found that density gradient centrifugation activated the NK cells and modified the chemokine receptor expression. Delays in processing beyond 8h activated NK cells in PBMC but not in whole blood. Likewise, processing delays decreased chemokine receptor (CCR4 and CCR7) expression in both PBMC and whole blood. Finally, delays in processing PBMC were associated with a decreased ability of NK cells to degranulate (as measured by CD107a expression) or secrete cytokines (IFN-? and TNF-?). In summary, our findings suggest that density gradient centrifugation and delayed processing of PBMC can alter measures of clinically relevant NK cell characteristics including effector functions; and therefore should be taken into account in designing clinical research studies.

SUBMITTER: Naranbhai V

PROVIDER: S-EPMC3051017 | biostudies-literature | 2011 Mar

REPOSITORIES: biostudies-literature

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Impact of blood processing variations on natural killer cell frequency, activation, chemokine receptor expression and function.

Naranbhai Vivek V Bartman Pat P Ndlovu Dudu D Ramkalawon Pamela P Ndung'u Thumbi T Wilson Douglas D Altfeld Marcus M Carr William H WH

Journal of immunological methods 20110119 1-2

Understanding the role of natural killer (NK) cells in human disease pathogenesis is crucial and necessitates study of patient samples directly ex vivo. Manipulation of whole blood by density gradient centrifugation or delays in sample processing due to shipping, however, may lead to artifactual changes in immune response measures. Here, we assessed the impact of density gradient centrifugation and delayed processing of both whole blood and peripheral blood mononuclear cells (PBMC) at multiple t ...[more]

PMID: 21255578

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Project description:Recent reports suggest that Natural Killer (NK) cells may modulate pathogenesis of primary HIV-1 infection. However, HIV dysregulates NK-cell responses. We dissected this bi-directional relationship to understand how HIV impacts NK-cell responses during primary HIV-1 infection.Paired samples from 41 high-risk, initially HIV-uninfected CAPRISA004 participants were analysed prior to HIV acquisition, and during viraemic primary HIV-1 infection. At the time of sampling post-infection five women were seronegative, 11 women were serodiscordant, and 25 women were seropositive by HIV-1 rapid immunoassay. Flow cytometry was used to measure NK and T-cell activation, NK-cell receptor expression, cytotoxic and cytokine-secretory functions, and trafficking marker expression (CCR7, ?(4)?(7)). Non-parametric statistical tests were used. Both NK cells and T-cells were significantly activated following HIV acquisition (p?=?0.03 and p<0.0001, respectively), but correlation between NK-cell and T-cell activation was uncoupled following infection (pre-infection r?=?0.68;p<0.0001; post-infection, during primary infection r?=?0.074;p?=?0.09). Nonetheless, during primary infection NK-cell and T-cell activation correlated with HIV viral load (r?=?0.32'p?=?0.04 and r?=?0.35;p?=?0.02, respectively). The frequency of Killer Immunoglobulin-like Receptor-expressing (KIR(pos)) NK cells increased following HIV acquisition (p?=?0.006), and KIR(pos) NK cells were less activated than KIR(neg) NK cells amongst individuals sampled while seronegative or serodiscordant (p?=?0.001;p<0.0001 respectively). During HIV-1 infection, cytotoxic NK cell responses evaluated after IL-2 stimulation alone, or after co-culture with 721 cells, were impaired (p?=?0.006 and p?=?0.002, respectively). However, NK-cell IFN-y secretory function was not significantly altered. The frequency of CCR7+ NK cells was elevated during primary infection, particularly at early time-points (p<0.0001).Analyses of immune cells before and after HIV infection revealed an increase in both NK-cell activation and KIR expression, but reduced cytotoxicity during acute infection. The increase in frequency of NK cells able to traffic to lymph nodes following HIV infection suggests that these cells may play a role in events in secondary lymphoid tissue.

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Impact of blood processing variations on natural killer cell frequency, activation, chemokine receptor expression and function.

Publications

Impact of blood processing variations on natural killer cell frequency, activation, chemokine receptor expression and function.

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