Abstract
Objective: In explaining the association between depression and immune system pro-inflammatory cytokines have come to the fore and there appears to be an increase in particular at the cellular immune response. Neopterin measurements enable monitoring of the cellular immune response although its specific function is still not fully described. Similarly, haptoglobin (Hp), a positive acute phase protein, has been mentioned as well. In this study, we aimed to investigate the effects of depressive episodes on serum levels of neopterin and Hp by comparing serum haptoglobin and neopterin levels of the depressive patients in their first attack with those of depression patients suffering from recurrent attacks, and with the healthy control group.

Method: Eighty patients who admitted to the outpatient psychiatry clinic of Ankara Gulhane Military Medical Academy (GMMF) were included in the study. Fourty-four individuals were being followed up with a diagnosis of first episode depression. There were 36 patients in the recurrent major depression (MD) group. The control group consisted of 41 healthy individuals. Of recurrent MD patients, 22 patients were in their second episode, 16 patients were in their third attack and 6 patients had four episodes or more. Severity of depression was evaluated with 17-item Hamilton Depression Rating Scale (HAM-D). Peripheral venous blood samples were collected from participants to determine complete blood count, routine biochemistry, serum neopterin, and haptoglobin measurements. The levels of serum neopterin and haptoglobin were measured by using the samples that were collected between the hours of 8:00 am and 11:00 am after 12 hour fasting during the previous night.

Results: There was no significant difference between the three groups in terms of gender, age, educational level, and smoking. There was also not significant difference between the first episode MD and recurrent MD groups for HAM-D scores. No significance was detected between the first episode MD and control groups in terms of serum Hp and neopterin levels. In the recurrent MD group serum Hp and neopterin levels were higher than those of the first episode MD patients and the control subjects. HAM-D scores of MD patients (both first-episode MD and recurrent MD group) were correlated with serum levels of Hp, but there was no correlation between serum neopterin levels and HAM-D scores.

Conclusion: The independent factor affecting the neopterin and Hp levels in patients with MD was found as the number of episodes of depression. Recurrent episodes have resulted with increased levels of both markers. We believe that this finding is important. Our findings support the hypothesis that major depressive disorder is generally associated with widespread inflammatory reaction and severity of depressive symptoms are positively correlated with the increase in inflammatory markers. Serum levels of Hp were associated with depression severity in patients who had a sin

Key words: depression, neopterin, haptoglobins