Neopterin ELISA

Neopterin

is a small molecule with a low molecular weight (253.21 g/mol) and belongs to the group known as pteridines. It is synthesized upon a cellular immune reaction. When macrophages and dendritic cells are stimulated by interferon-ɣ, neopterin is released. Neopterin values reflect the entire immunological processes for monocytes/ macrophages and dendritic cells and can be seen as a global immune response marker.

Figure 1: Release of Neopterin during cellular immune reaction [1].

An increase in neopterin concentration marks the onset of an infection in the body before antibodies are present. As soon as the immune system is triggered by interferon-ɣ, neopterin is released by macrophages.

Neopterin is related to [2]:

• Early indication of viral infections (e.g. SARS-CoV-2, HIV)
• Differentiation of acute viral and bacterial infections
• Indications for autoimmune diseases (e.g. Sjörgren-syndrome, rheumatic diseases)
• Early indication of complications in allograft rejection episodes
• Follow-up control of chronic infections, therapy and treatment

Insights and cues from neopterin: Synthesized upon stimulation of macrophages and dendritic cells, neopterin is an early, well-characterized biochemical marker of an ongoing immune reaction to viral infection [2]. 

Figure 2: Schematic time course of neopterin concentration in blood in relation to the rise and fall of antibody presence in response to viral infection [2].

Measurement in bodily fluids: The determination of neopterin levels in human body fluids offers a useful and innovative tool to monitor diseases associated with the activation of cell-mediated immunity. The ELISA is validated for measuring Neopterin in serum, plasma (EDTA). Neopterin has a higher stability in body fluids which makes the sample handling and measurement easier compared to other cytokines. The low molecular weight, enables Neopterin molecules to pass rapidly through the intravasacular area, where it is released into urine after glomerular filtration. The half-life in the human body is only affected by renal excretion.

Increasing Neopterin levels in various infections precede the clinical manifestation and seroconversion. Normally samples are not tested for all possible infections. Therefore, the measurement of Neopterin in blood donor samples is a useful tool in order to reduce the risk of infections via blood transfusion [2].

Neopterin is helpful since it allows an immediate response for interventions during the early phase of the “diagnostic window”, which indicates the timespan of pathogen invasion and onset of antibodies. Due to the early increase of neopterin therapeutic measures can be taken before the appearance of the antibodies.