The gene product of the steel locus of the mouse represents a growth factor for murine mast cells and a ligand for the c-kit proto-oncogene receptor, a member of the tyrosine kinase receptor class of oncogenes (for review, see O. N. Witte. 1990. Cell 63:5). We have studied the effect of the human recombinant c-kit receptor ligand stem cell factor (rhSCF) on the release of inflammatory mediators from human skin mast cells and peripheral blood basophils and compared its activity to that of rhIL-3. rhSCF (1 ng/ml to 1 μg/ml) activated the release of histamine and PGD2 from mast cells isolated from human skin. Analysis by digital video microscopy indicated that purified human skin mast cells (84 ± 5% pure) responded to rhSCF (0.1 to 1 μg/ml) challenge with a rapid, sustained rise in intracellular Ca2+ levels that was accompanied by secretion of histamine. A brief preincubation (10 min) of mast cells with rhSCF (0.1 pg/ml to 1 ng/ml) significantly enhanced (100 ± 35%) the release of histamine induced by anti-IgE (3 μg/ml), but was much less effective on IgE-mediated release of PGD2. In contrast, a short term incubation with rhSCF did not potentiate the secretion of histamine activated by substance P (5 μM). A 24-h incubation of mast cells with rhSCF did not affect the release of mediators induced by anti-IgE (3 μg/ml), probably due to receptor desensitization. rhSCF (1 ng/ml to 3 μg/ml) neither caused release of histamine or leukotriene C4 (LTC4) release from leukocytes of 14 donors, nor induced a rise in intracellular Ca2+ levels in purified (>70%) basophils. Brief preincubation (10 min) of leukocytes with rhSCF (1 ng/ml to 3 μg/ml) caused an enhancement (69 ± 11%) of anti-IgE- induced release of histamine that was significant at concentrations as low as 3 ng/ml (p < 0.05), whereas it appeared less effective in potentiating IgE- mediated LTC4 release. In contrast, a prolonged incubation (24 h) with rhSCF (0.1 pg/ml to 100 ng/ml) did not enhance the release of histamine or LTC4 induced by anti-IgE (0.1 μg/ml), whereas rhIL-3 (3 ng/ml) significantly potentiated the release of both mediators. A pretreatment with a mAb directed against the human c-kit receptor (8 μg/ml) abolished the enhancement of IgE- mediated histamine release induced by a 10-min incubation with rhSCF (1 to 3 μg/ml). Indirect immunofluorescence and flow-cytometric analysis revealed that human basophils do express the c-kit receptor on their cell membrane, although the level of expression was much lower than that of mast cells. Our data demonstrate that rhSCF can enhance the immunologically stimulated release of histamine from human skin mast cells and peripheral blood basophils, and that the skin mast cell can be activated by this gene product. It can be hypothesized that, under certain circumstances, rhSCF may represent a mast cell or basophil activating/modulating factor in human allergic reactions. Moreover, some of the effects of rhSCF on mast cell mediator release in vitro occurred at concentrations of the cytokine similar to those present in the serum of normal subjects in vivo. This suggests that SCF may also modulate mast cell function under physiologic conditions.
|Original language||English (US)|
|Number of pages||10|
|Journal||Journal of Immunology|
|State||Published - 1992|
ASJC Scopus subject areas
- Immunology and Allergy