Depressive symptomatology is associated with decreased interleukin-1 beta and increased interleukin-1 receptor antagonist levels in males.

Previous studies with selected patient populations have suggested that cytokines, the immune system messengers, may play a role in the aetiology of depression. However, the data concerning the increase or decrease of the plasma cytokine levels in depression is controversial and the effects of the medications and type of depression are largely unknown. We studied the connections between plasma interleukin-1 beta (IL-1 beta) and interleukin 1 receptor antagonist (IL-1RA) levels, and depressive symptomatology measured with the Beck Depression. Inventory in a large, middle-aged population-based sample collected from Central Finland. In addition, the effects of various medications and type of depressive symptomatology on the cytokine levels were scrutinized. In the whole study population, IL-1RA levels were higher in the subgroup with depressive symptomatology. In the males with depressive symptomatology, higher IL-1RA levels and lower interleukin-1 beta levels were observed as compared with the non-depressed males. The IL-1RA/IL-1 beta ratio was significantly higher in males with depressive symptomatology. The IL-1RA levels were also higher and IL-1 beta levels lower in the depressed females, but the trend was not significant. The elevated IL-1RA-levels and IL-1RA/IL-1 beta ratio suggest a role for cytokines in the pathogenesis of depression. The higher IL-1RA levels may reflect an endogenous repairing process against depression.