P176Relationship between natural killer cells and platelet reactivity in patients with acute coronary syndrome

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Abstract

Purpose

Preliminary studies show that patients with Coronary Artery Disease (CAD) present reduced NK cell compartment and low cytotoxic NK activity. NK cell functions may be affected by inflammatory processes with consequent impairment of immunological response leading to progression of CAD. High levels of inflammation associated with enhanced platelet aggregation are typical of acute phases of coronary disease. Thus, we analyzed the relationship between thrombogenicity and NK cell distribution in patients with non-ST-elevation acute coronary syndrome (NSTEACS).

Methods

Peripheral blood samples were taken from 50 statin-naïve patients with NSTEACS and analyzed for the distribution of NK cells by Flow Cytometry (using anti-CD3, -CD8, -CD16 + 56, -CD57 monoclonal antibodies) and for platelet reactivity by the VerifyNow P2Y12 assay. Platelet reactivity was measured as residual ADP induced aggregation (PRU) after P2Y12 receptor blockade and as thrombin induced aggregation (Base PRU) which provides an estimation of total platelet reactivity.

Results

Overall, there were a significant positive correlation between PRU and Base PRU values (r = 0.38, p=.02) and inverse correlations between the absolute number of NK cells (CD3-CD16 + 56 + and CD8-CD57 + ) and PRU (p < 0.05) and Base PRU (p < 0.01). We divided the patient population into two groups: Low Reactivity (Base PRU < 305) and High Reactivity (Base PRU ≥ 305). NK cell frequencies were significantly lower in the High Reactivity than the Low Reactivity group (Figure 1).

Conclusions

This study shows that in patients with NSTEACS there is a link between platelet reactivity and NK cell distribution. As PRU values correlate with clinical outcome, our results may suggest a possible link between NK cell frequencies and prognosis in patients with ACS.

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