Murine and human mast cells express acetylcholinesterase

Since mast cells are present in proximity to neurons in many organs, mast cell-nerve interactions may have important physiological functions. As the hydrolyzing enzyme acetylcholinesterase (AChE) is responsible for terminating acetylcholine effects on the post-synaptic membrane, we examined whether this enzyme is expressed in mast cells. Acetyl thiocholine hydrolysis measurements with selective inhibitors revealed that murinc mast cells express catalytically active AChE and the related enzyme buterylcholinesterase. The primary type of AChE mRNA produced by the murinc mast cells was found to be the brain and muscle type as determined by PCR amplification of alternative exons from the 3' end of mast cells AChE cDNA. Similar analysis further detected AChE mRNA expression in the human mast cell precursor cell line (HMC-1). Furthermore, utilizing the sensitive single cell RT-PCR method we detected AChE mRNA expression also in FceRI-positive single cells derived from human colonie mucosal biopsies. Our findings predict the involvement of mast cell AChE in neuronal-mast cell interactions.