MACROPHAGE-COLONY-STIMULATING FACTOR STIMULATES SYNTHESIS AND SECRETION OF A MOUSE HOMOLOG OF A HUMAN IGE-DEPENDENT HISTAMINE-RELEASING FACTOR BY MACROPHAGES IN-VITRO AND IN-VIVO

Treatment of murine resident peritoneal macrophages with macrophage-CS F (M-CSF) up-regulated the synthesis of a discrete set of proteins, in cluding a 26-kDa protein (p26), The sequence of 20 NH2-terminal amino adds of the purified p26 was identical with the mouse homolog of a hum an IgE-dependent histamine-releasing factor (HRF). Among macrophage ac tivators tested (M-CSF, granulocyte-macrophage-CSF, IL-3, TNF-alpha, I FN-gamma, and LPS), only M-CSF could up-regulate the p26 HRF synthesis by cultured macrophages. M-CSF not only increased the levels of p26 H RF mRNA and protein, but also stimulated the secretion of an N-glycosy lated p26 HRF with a m.w. of 30 kDa, Repeated injections of M-CSF into mouse peritoneal cavity for 4 days elicited macrophages expressing ab undant p26 HRF. A single i.p. injection of M-CSF failed to increase th e p26 HRF level in peritoneal macrophages of thioglycollate-, LPS-, or adjuvant-treated mice, while M-CSF challenge to OVA-immunized mice ca used macrophage infiltration and overproduction of p26 HRF, similarly as did OVA challenge. The Ag-specific priming for enhanced synthesis a nd secretion of p26 HRF by M-CSF was also demonstrated in cultured mac rophages prepared from OVA-immunized mice. An i.p. injection of M-CSF or recombinant p26 HRF triggered eosinophil recruitment, even in the a bsence of the Ag, in the sensitized mice, but not in normal mice. Furt hermore, recombinant p26 HRF could induce eosinophilia without marked macrophage and lymphocyte infiltrations, Our results suggest that p26 HRF secreted by M-CSF-stimulated macrophages may be an important media tor for the late phase allergic inflammation.