Neopterin

Neopterin is a catabolic product of Guanosine triphosphate (GTP), a purine nucleotide.

Neopterin belongs to the chemical group known as pterins. It is synthesised by macrophages (activated T cell) upon stimulation with the cytokine interferon-gamma and is indicative of a pro-inflammatory immune status. Neopterin serves as a marker of cellular immune system activation.

Neopterin as disease marker
Measurement of neopterin concentrations in body fluids like blood serum, cerebrospinal fluid or urine provides information about activation of cellular immune activation in humans under the control of T helper cells type 1. High neopterin production is associated with increased production of reactive oxygen species, neopterin concentrations also allow to estimate the extent of oxidative stress elicited by the immune system.

Increased neopterin production is found in, but not limited to, the following diseases:


 * viral infections including human immunodeficiency virus (HIV), hepatitis B and Hepatitis C


 * bacterial infections by intracellular living bacteria such as borrelia (Lyme Disease) and mycobacterium tuberculosis


 * parasites such as malaria


 * autoimmune diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE)


 * malignant tumor diseases


 * allograft rejection episodes.

Neopterin concentrations usually correlate with the extent and activity of the disease, and are also useful to monitor during therapy in these patients.

In the laboratory it is measured by radioimmunoassay (RIA), ELISA, or High-performance liquid chromatography (HPLC). It has a native fluorescence of wavelength excitation at 353nm and emission at 438nm making it readily detected.