IDENTIFICATION OF HISTAMINE-PRODUCTION-INCREASING FACTOR PRODUCED BY STIMULATED RBL-2H3 RAT BASOPHILIC LEUKEMIA-CELLS AS GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR

When RBL-2H3 rat basophilic leukemia cells were stimulated by antigen or the Ca2+ ionophore A23187, the activity to increase histamine produ ction by rat bone marrow cells in the conditioned medium increased tim e-dependently. To characterize the histamine-production-increasing fac tor (HPIF) produced by RBL-2H3 cells, the conditioned medium was colle cted 8 h after stimulation by A23187, and the factor was purified by t hree-step chromatography, the specific activity being increased by 900 0-fold. The partial amino acid sequence of the peptide obtained by S. aureus V8 protease digestion was identical to the internal amino acid sequence of rat granulocyte-macrophage colony-stimulating factor (CM-C SF), In addition, GM-CSF mRNA levels in RBL-2H3 cells were increased b y A23187 with a peak at 4 h. Furthermore, recombinant rat GM-CSF incre ased histamine production by rat bone marrow cells. These findings sug gested that HPIF produced by the stimulated RBL-2H3 cells is GM-CSF. P ossible significant roles of HPIF at the late phase of allergic inflam mation are discussed. (C) 1998 Elsevier Science B.V. All rights reserv ed.