Histamine production by cultured microglial cells of the mouse

We previously reported that cells other than mast cells or neurons could sy nthesize histamine in response to lipopolysaccharide (LPS) or interleukin 1 beta in the rat brain. To identify the responsible cells, we examined hist idine decarboxylase (HDC) activity and the expression of HDC mRNA in GMI 6- 3 mouse microglial cells. Both the activity and mRNA for HDC in GMI 6-3 cel ls were induced by LPS treatment, and the induction was sensitive to calmod ulin-dependent kinase II inhibitor, KN62. These findings indicate that micr oglia is a third cell type producing histamine in the brain. (C) 2001 Elsev ier Science Ireland Ltd. All rights reserved.