Relationship between serum neopterin and lymphocytic alveolitis in sarcoidosis

We have previously found elevated levels of serum (S-) neopterin in patients with active sarcoidosis. In the present study we therefore investigated the relationship between elevated S-neopterin and sarcoid alveolitis as reflected in bronchoalveolar (BAL) findings. Patients with elevated percentages of BAL-lymphocytes (n = 19) had significantly higher (p less than 0.01) S-neopterin levels (median 12.1 nmol/L) than those (n = 11) with normal percentages (median 8.5 nmol/L). Of 19 patients with elevated lymphocyte percentage 18 had increased S-neopterin. There was a significant correlation between S-neopterin levels and the concentration (p less than 0.01) as well as the percentage (p less than 0.05) of BAL-lymphocytes. On the other hand, no correlation was found between S-neopterin and the BAL-albumin/S-albumin ratios, the concentration of macrophages or the concentration of angiotensin converting enzyme in the BAL fluid. The results indicate a close relationship between S-neopterin and lymphocytic alveolitis in sarcoidosis. Furthermore, a possible relationship between elevated S-neopterin and the ratios of T helper to T cytotoxic-suppressor cells (TH/TC-S) in blood, assumed to reflect changes of the ratios in alveolitis, was examined. However, 34 of 37 sarcoid patients had TH/TC-S ratios within the normal range. The ratios of patients with normal and elevated S-neopterin did not differ.