A pilot study on the association between job stress and repeated measures of immunological biomarkers in female nurses

To evaluate the immunosuppressive effects of job stress in female nurses, an 8-month longitudinal study was conducted at a major university hospital. Four groups of ten subjects each were constructed to represent high versus low objective stress and high versus low subjective stress based on their responses to a job stress questionnaire and objective stress ratings of the hospital’s work units. Number of white blood cells (i.e., T cells, B cells, and natural killer cells), and lymphocytic proliferation to mitogens (concanavalin A, phytohemagglutinin, and pokeweed) and toxoid (tetanus) were measured by flow cytometry and radioimmunoassay. Serum levels of hydrocortisol, IL-1β, IFN-γ, and TNF-α, and salivary IgA were measured by enzyme-linked immunosorbent assay. The data were analyzed by repeated measures analysis of variance controlling for age and smoking. The level of white blood cells was lower among high objective stress group (median: 7,170/m3; range: 5,386–10,057) compared with that among low objective stress group (8,063; 5,888–9,875) (P = 0.03), however, no other cellular blood variables were found to be significant. In terms of humoral immuno-biomarkers, the level of TNF-α was moderately lower among high objective stress group (1.7 ng/ml; 0.3–2.7) compared with that among low objective stress group (2.2; 0.5–3.5) (P = 0.07), whereas the level of total sIgA was significantly higher among higher objective stress group (72.9 end-point titer/mg/ml/min; 14.4–153.4) compared with that among low objective stress group (44.8; 9.9–123.8) (P = 0.02). The results of the study suggest that psychological job stress affects the levels of some immunological biomarkers in female nurses.