[Neopterin and its importance in clinical diagnosis]

Despite a rapid progress of the understanding of the role of cytokines in etiopathogenesis of many disorders, our capability to detect this process is still limited. Neopterin, which is produced by activated macrophages under the control of interferon-gamma, is one of the indices of immune activation. The physiological role of the neopterin is not yet clear, but the antioxidant properties of its derivatives may be of importance. A rise in urinary neopterin excretion, which correlates with its serum level, is observed in various clinical conditions linked to the activation of cellular immunity, e.g. in patients with viral infections, transplantation complications, tumors, or autoimmune diseases, but elevated neopterin demonstrates the role of immunity also in conditions where it is less obvious, e.g. in acute myocardial infarction. Neopterin determination, which represents a very sensitive, albeit unspecific index of disease activity is used mostly for longitudinal follow-up of patients, under certain circumstances, however, this method may be useful in differential diagnosis.