PHENOTYPIC EVALUATION OF CULTURED HUMAN MAST AND BASOPHILIC CELLS ANDOF NORMAL HUMAN SKIN MAST-CELLS

In order to evaluate various markers for human mast cells, two human m ast/basophilic cell lines (HMC-1/KU812), cultured mast cells from the peripheral blood monocytic fraction and peripheral blood monocytes wer e compared with mast cells in tissue sections from normal skin, using histochemistry, enzyme histochemistry and immunohistochemistry. All re agents stained normal skin mast cells, with toluidine blue, tryptase r eactivity and antibodies against the Fc epsilon RI and the stem cell f actor receptor (c-kit) being most active. The cell lines and mast cell s cultured from peripheral blood were negative for avidin, safranin an d chymase, strongly positive for c-kit and variably reactive with all other reagents. All antibodies except AAI against tryptase also staine d one or several epidermal and dermal cell types or blood monocytes. H istochemical stains (toluidine blue, avidin) and reagents for the enzy mes tryptase and chymase are thus specific markers for mast cells. The frequent reactivity of antibodies against mast cells with other cell types indicates interesting functional and ontogenetic relationships b etween these cells.