85. Whole blood, as opposed to washed blood, is resistant to suppression of NK cell cytotoxicity by stress factors: Do behavioral stressors directly suppress activity of circulating NK cells in vivo ?

• Published in: Brain, behavior, and immunity Vol. 32; p. e25
• Main Authors: Gotlieb, N, Rosenne, E, Sorski, L, Shaashua, L, Matzner, P, Ben-Eliyahu, S
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.09.2013
• Subjects: Allergy and Immunology; Psychiatry
• ISSN: 0889-1591; 1090-2139
• DOI: 10.1016/j.bbi.2013.07.097

In vitro studies assessing the impact of stress factors on immune competence employ “washed” leukocytes incubated in artificial media (e.g., PBMC in RPMI-1640), not reflecting the potential modulating impact of plasma factors on such effects, and deviating from the in vivo conditions where stress effects should ideally be studied. Therefore, here we compared human whole blood to washed blood (plasma replaced by RPMI-1640), studying the impact of cortisol, prostaglandin-E2, epinephrine, and metaproterenol (a non-selective beta-adrenergic agonist) on NK cell cytotoxicity (NKCC). Cortisol suppressed NKCC dose-dependently in washed blood, but had no effect in whole blood (baseline to stress concentrations: 10–7, 3*10–7, 10–6, and 3*10–6 M). Prostaglandin-E2, epinephrine, and metaproterenol, had no impact at systemic physiological concentration, and suppressed NKCC in washed blood only at concentrations higher than 10–8 M. Moreover, in whole blood, 3–10-fold higher concentrations of these factors were needed to suppress NKCC, yielding markedly smaller suppression than in washed blood. These findings suggest that the effects of stress factors on standard in vitro preparations of washed leukocytes are an overestimation of their impact in whole blood or in vivo . If indeed true, the common findings of ex-vivo stress-induced suppression of NKCC may not be a consequence of direct suppression of circulating NK cells, but may rather reflect an influx of NK cells of lower cytotoxicity into the circulation.