Pharmaceutical agent cetylpyridinium chloride inhibits immune mast cell function by interfering with calcium...

Cetylpyridinium chloride (CPC) is an antimicrobial used in numerous personal care and janitorial products and food for human consumption at millimolar concentrations. Minimal information exists on the eukaryotic toxicology of CPC. We have investigated the effects of CPC on signal transduction of the immune cell type mast cells. Here, we show that CPC inhibits the mast cell function degranulation with antigen dose-dependence and at non-cytotoxic doses ∼1000-fold lower than concentrations in consumer products. Previously we showed that CPC disrupts phosphatidylinositol 4,5-bisphosphate, a signaling lipid critical for store-operated Ca²⁺ entry (SOCE), which mediates degranulation. Our results indicate that CPC inhibits antigen-stimulated SOCE: CPC restricts Ca²⁺ efflux from endoplasmic reticulum, reduces Ca²⁺ uptake into mitochondria, and dampens Ca²⁺ flow through plasma membrane channels. While inhibition of Ca²⁺ channel function can be caused by alteration of plasma membrane potential (PMP) and cytosolic pH, CPC does not affect PMP or pH. Inhibition of SOCE is known to depress microtubule polymerization, and here we show that CPC indeed dose-dependently shuts down formation of microtubule tracks. In vitro data reveal that CPC inhibition of microtubules is not due to direct CPC interference with tubulin. In summary, CPC is a signaling toxicant that targets Ca²⁺ mobilization.