Relative amounts of mRNA encoding four subtypes of muscarinic receptors (m2-m5) in human peripheral blood mononuclear cells

It is known that lymphocytes express functional muscarinic cholinergic rece ptors. In this study, RT-PCR method was applied to study the presence and r elative levels of mRNA encoding muscarinic receptor subtypes in human perip heral blood mononuclear cells (PBMCs). Our results, confirmed by DNA sequen cing, demonstrate the presence of m2, m3, m4, and m5 receptor subtypes in h uman PBMCs. The relative levels of muscarinic receptor subtypes fit the fol lowing pattern: m3 > m5 > m4 > m2. Our data provide strong evidence confirm ing previous pharmacological studies that suggested the existence of severa l subtypes of muscarinic receptors on human PBMCs. We cannot exclude the po ssibility that expression of receptor subtype depends on the lineage and/or activation status of the cell. (C) 1999 Elsevier Science B.V. All rights r eserved.