THE EFFECT OF RECOMBINANT STEM-CELL FACTOR ON HUMAN SKIN AND LUNG MAST-CELLS AND BASOPHIL LEUKOCYTES

Recombinant human stem cell factor (rhSCF) induced histamine release f rom human skin and lung mast cells but had no effect on human basophil leukocytes. More importantly, rhSCF enhanced the release of histamine in response to IgE-crosslinking of human mast cells. This potentiatio n was observed at rhSCF concentrations which induced histamine release , and also at lower concentrations of the ligand which by themself pro duced no effect. Very limited potentiation was observed with human bas ophil leukocytes. The enhancing effect of SCF was unique to IgE-depend ent stimulation and when SCF was incubated with the neurotransmitter s ubstance P and the calcium ionophore A23187, no augmentation of histam ine release was observed with any of the cell types tested. These find ings suggest that endogenous SCF may contribute to the regulation of m ast cell function and may hence play a role in diverse allergic and in flammatory reactions.