Job satisfaction is associated with elevated natural killer cell immunity among healthy white-collar employees

Although the association of job satisfaction with health has been well documented, little is known about the biological mechanisms underlying this relationship. This study investigates the association of job satisfaction with cell-mediated immunity among Japanese white-collar daytime workers. A total of 306 healthy full-time employees (141 women and 165 men), aged 22-69 (mean 36) years, provided a blood sample for the measurement of circulating immune (natural killer (NK), B, and total T) cells and NK cell cytotoxicity (NKCC) and completed a questionnaire survey during April to June 2002. Job satisfaction was measured by a 4-item scale from the Japanese version of the generic job stress questionnaire with higher scores indicating greater satisfaction. Analyses were done separately for women and men using a hierarchical multiple linear regression model controlling for multiple confounders. The results revealed that greater job satisfaction was positively correlated with NKCC (β=.207; p=.029) and the number of NK (CD3^-CD56⁺) cells (β=.261; p=.008) in women. In men, job satisfaction was marginally correlated with NKCC (β=.165; p=.050) but was not correlated with the number of NK (CD3^-CD56⁺) cells (β=.142; p=.107). Job satisfaction did not correlate with numbers of T (CD3⁺CD56^-) and B (CD19⁺) cells in both women and men. Our findings suggest an independent association between job satisfaction and NK cells but the association seems to be stronger in women than in men. Although the results provide a support for the biological plausibility of the job satisfaction-health relationship, additional research is required to determine whether greater job satisfaction contributes to recovery/maintenance of NK cell immunity and host defense over time.