Procalcitonin and its Component Peptides in Systemic Inflammation: Immunochemical Characterization

Abstract

These studies indicate that ProCT and its component peptides circulate in normal persons. The serum of patients with SIRS/sepsis contains greatly increased levels of ProCT, nProCT and often, CT:CCP-I. However, in this condition, post-translational processing is incomplete, resulting in mature CT levels that are normal or minimally elevated. In contrast, patients with neuroendocrine cancer have considerably high mature CT levels. Interestingly, although serum CGRP levels often are high in neuroendocrine cancer, they are low in SIRS/sepsis. The marked hyperprocalcitonemia of SIRS/sepsis is probably a consequence of the pro-inflammatory cytokine cascade, and appears to be secreted in a constitutive fashion; the cell(s) of origin of this remarkable hypersecretion is unknown. There is a very marked positive correlation between serum levels of ProCT and nProCT, and the lower level of sensitivity for nProCT may make its measurement a more useful marker for early or mild SIRS/sepsis.