In people with stable heart disease, a simple blood test that looks at the ratio of monocytes to lymphocytes (MLR) goes up when they feel more depressed and when stress‑related hormones and inflammation markers—including the peptide LL‑37—are higher. This suggests MLR could be a cheap way to see how stress and inflammation are interacting in the body.

Psychosocial stress and depression have been recognized as major risk factors of coronary artery disease (CAD). Although monocytes are known to be key players in atherosclerosis, monocyte-based associations with psychoneuroendocrino-immuno-inflammatory (PNI) markers have not been widely investigated in stable CAD. We examined associations between the monocyte-to-lymphocyte ratio (MLR) and key PNI markers in stable CAD. We studied 23 patients with stable CAD who completed the Beck Depression Inventory (BDI) and Rahe's Brief Stress and Coping Inventory. A white blood cell differential was performed, and levels of cortisol, chromogranin A (CgA), LL-37, interleukin-6 (IL-6) and C-reactive protein (CRP) were assayed in plasma. Monocyte fraction, MLR and plasma CgA levels exceeded reference values, the social support score was low, and 7 patients had elevated BDI scores. In the multivariate-adjusted analysis, a higher MLR was associated with greater depressive symptom severity (r = 0.624, p < 0.01) as well as with higher concentrations of CgA (r = 0.660, p < 0.01), LL-37 (r = 0.643, p < 0.01), IL-6 (r = 0.532, p < 0.05) and CRP (r = 0.470, p < 0.05). BDI scores associated with CgA concentration (r = 0.618, p < 0.01) and CgA level correlated negatively with the social support score (r = -0.511, p < 0.05). Our findings suggest that, in patients with stable CAD, elevated MLR may be associated with depressive symptoms, with increased neuroendocrine-sympathetic activity (marked by CgA) and inflammatory markers that are pertinent to atherosclerosis initiation and progression. The increased neuroendocrine-sympathetic activity correlated with low social support and depressive symptom severity. The MLR might serve as an easy-to-obtain and inexpensive proxy measure of an activated PNI network in stable CAD.