Quantifying Transient Psychological Stress Using a Novel Technique: Changes to PMA-Induced Leukocyte Production of ROS In Vitro

Abstract

Although much work has been conducted to quantify the long-term physiological effects of psychological stress, measures of short-term, low-level stress have been more elusive. This study assessed the effect of exposure of volunteers to a mild, brief, psychologically stressful event, on the functional ability of leukocytes in whole blood to respond to phorbol 12-myristate 13-acetate (PMA) in vitro. Volunteers operated a car electric window and adjusted it to 4 pre-determined positions. Between each operation the mechanism's polarity was covertly altered (group B) or remained unaltered (group A). For each treatment group 10 different subjects provided capillary blood samples pre- and post-stressor. Using a chemiluminescent technique termed leukocyte coping capacity, the ability of leukocytes to produce reactive oxygen species (ROS) in vitro was assessed. ROS release differed significantly at 10 min post-stressor between treatment groups, suggesting exposure to acute psychological stress leads to a reduced ability to respond to bacterial challenge.

Leukocyte responsiveness, a quantitative assay for subjective mental workload

“…Stress has been shown to influence the number, distribution and activation state of neutrophils in the blood in a rapid and reversible manner (Dhabhar et al, 1995;Goebel and Mills, 2000;McLaren et al, 2003;Mian et al, 2003;Shelton-Rayner et al, 2011. When compared to the stressor paradigm utilised during this research, all previous examples utilised stressors that were of far greater duration and/or intensity.…”

“…Leukocyte Coping Capacity (LCC), i.e. their ability to respond to an external stimulator and produce reactive oxygen species, will be affected by the immediate external environment in the blood (Shelton-Rayner et al, 2011). Leukocytes (mainly neutrophils) which have been exposed to stressors within the body will have a reduced capacity to produce reactive oxygen species in response to an external stimulator (e.g.…”

“…Activated neutrophils release an array of mediators, including reactive oxygen species (Ruotsalainen et al, 1995). Chemiluminescent assay of Phorbol 12-myristate 13-acetate induced reactive oxygen species production by leukocytes has been shown to provide quantitative links between psychological anxiety and immune-competency Montes et al, 2004Montes et al, , 2003Shelton-Rayner et al, 2011Shelton-Rayner, 2009). The Leukocyte Coping Capacity (LCC) technique involves measuring leukocytes' ability to produce a respiratory burst, assayed in terms of Reactive Oxygen Species and calibrated through the emission of photons via their interaction with Luminol when stimulated using Phorbol 12-myristate 13-acetate in vitro .…”

“…The Leukocyte Coping Capacity (LCC) test monitors the multifaceted effects of stress using the body's leukocytes (primarily, but not exclusively, neutrophils) as bioindicators (Shelton Rayner et al, 2011. These cells circulate throughout the body picking up and responding to all of the signals of stress (illustrated in Figure 1).…”

“…Instead, assessment of physiological characteristics including respiration rate and skin conductance (Oetting, 1966;Sher et al, 2007) in addition to changes in heart rate and variability, blood pressure and body temperature are often utilised (Brown et al, 2006(Brown et al, , 2003DiDomenico and Nussbaum, 2011;Hodgson et al, 2004;Moon and Cho, 2001). Although these methods return rapid results, all are subject to considerable biological variation, introducing uncertainty during comparison between individuals and populations.The Leukocyte Coping Capacity (LCC) test monitors the multifaceted effects of stress using the body's leukocytes (primarily, but not exclusively, neutrophils) as bioindicators (Shelton Rayner et al, 2011. These cells circulate throughout the body picking up and responding to all of the signals of stress (illustrated in Figure 1 , 2011).…”