Urinary neopterin quantification indicates altered cell-mediated immunity in healthy subjects under psychological stress.

In an effort to quantify changes in cell-mediated immunity (CMI) in healthy subjects under stress, we measured levels of neopterin, a well-validated marker of CMI activation, in the urine of medical students undergoing academic examinations. Neopterin/creatinine ratios measured on the first day of examinations (mean 46 mumol/mol) were significantly lower than those measured two weeks before (mean 78 mumol/mol, p = .004). Minimum neopterin production coincided with maximum subjective stress, as measured by a visual analogue scale. After examinations, neopterin/creatinine ratios rose (means 62 mumol/mol immediately after, and 65 mumol/mol two weeks after examinations), and these levels were not statistically different from those two weeks before examinations. Over this post-examination period, subjective distress was significantly lower than at either time point before examinations. We conclude that urinary neopterin/creatinine ratios may change significantly during periods of psychological stress, indicating concomitant alterations in CMI activation.