Acute active, but not passive, psychological stress increases non-classical monocyte proportions

Objective: Psychological stress exposure is a modifiable risk factor for cardiovascular disease (CVD), possibly through promoting a heightened inflammatory milieu. Under psychological stress, changes in monocyte subsets from classical (CM) to intermediate (IM) and non-classical (NCM) could indicate a more pro-inflammatory environment. We investigated the impact of acute psychological stress (active and passive) on monocyte subsets and leukocyte count ratios.
Methods: Twenty-four participants completed a 20-min baseline period, followed by a passive
(International Affective Picture System: IAPS) and active stress task (socially evaluative Paced
Auditory Serial Addition Test: PASAT) with 90-min recovery after each task. Blood samples were
collected to determine changes in: CM, IM and NCM count/proportions, systemic inflammation
response index (SIRI) and neutrophil:lymphocyte ratio (NLR).
Results: CM proportions decreased (89.4% to 87.0%; p=.007) and NCM proportions increased (6.8%
to 2.1%; p=.035) from baseline to immediately post-PASAT. There were no differences in monocyte
subsets from baseline to post-IAPS (CM% p=1.00; IM% p=1.00; NCM% p=1.00). NLR and SIRI did not
differ from baseline in response to either the PASAT or IAPS (p>.05).
Conclusion: Acute active, but not passive, psychological stress promoted a transition in monocyte
subsets towards a more pro-inflammatory environment, which may be an important advancement in
markers used to assess the inflammatory response to acute psychological stress.