Depression, gender and cellular immunity: influence of gender and severity of depression on the cellular immunity.

BACKGROUND: Exposure to stress modifies the humoral and cellular immunity by the activation of the hypothalamic-pituitary-adrenal axis. On one hand, this psycho-immunological theory allows the analyse of links between immunity and depression. On the other hand, the correlation between the immune response, the clinical expression in major depressive disorder (MDD) and the gender was proven. Our analysis evaluates the influence of the gender and the level of depression severity on the cellular immune response associated with it.

SUBJECTS AND METHOD: 549 patients with MDD were enrolled in an open-ended survey. In addition to a socio-demographic questionnaire, they completed the Beck Depression Scale (BDS). Flow cytometry was used to assess lymphocyte subsets.

RESULTS: On average, the intensity of the depression (ID) among women is higher by 2.9 points (t=2.379*). In terms of immunity, there are correlations between this ID and absolute values of CD3 (r=-0.127***), CD4 (r=-0.189***), CD8 (r=0.089*) and CD16 and 56 (r=0.129*). In terms of gender, there are significant differences for the percentage of total lymphocytes (m=37.84, w=35.59; t=2.646***), CD3 (m=2.08, w=1.9; t=2.676*), CD4 (m=1.44, w=1.3; t =2.522*), CD8 (m=0.62, w=0.57; t=2.182*). A linear regression model including both variables supports the existence of these differences in the percentage of total lymphocytes (Adjusted R2=0.025***) and CD8 (Adjusted R2=0.012*).

CONCLUSIONS: If the link between depression and the cellular immune response is a known fact, our study proves that women have a stronger immune response than men in terms of percentage of total lymphocytes mobilized and cytotoxic lymphocytes. The volume of natural killer lymphocytes is independent of the gender but connected to the ID. Based on those results, psycho-immunological theories could potentially be rethought in the light of immunity being at least partially dependent of the gender.