<prompt> Which is biomarker of in ventilation associated pneumoniaProcalcitoninC - reactive proteinESRCA19-9  <response>: Procalcitonin PCT is a precursor of calcitonin that is constitutively secreted by C cells of the thyroid gland and K - cells of the lung. In healthy individuals PCT is undetectable when stimulated by endotoxin PCT is rapidly produced. 