Expression of stem cell factor in cutaneous mastocytosis

Abstract

Stem cell factor has recently been identified as a potent growth factor for bone marrow stem cells, melanocytes and mast cells. In order to evaluate its possible role in human mastocytosis, skin lesions from 13 patients with urticaria pigmentosa and five patients with mastocytomas, and normal skin specimens from five healthy donors were studied by immunohistochemistry, using polyclonal and monoclonal (hkl-12) antibodies against stem cell factor, and a monoclonal antibody (YB5.B8) against its receptor, the c-kit proto-oncogene product. Stem cell factor expression was noted in all sections studied, with an equal distribution pattern for both antibodies, but a weaker intensity with the hkl-12 reagent. Cytoplasmic staining was noted in keratinocytes, Langerhans cells, sweat gland ductal lining cells, mast cells, endothelial cells and spindle-shaped dermal stromal cells. An intense, diffusely granular reaction pattern was noted in all cells, except for a sparse, coarsely granular pattern in mast cells and stromal cells. In urticaria pigmentosa, staining was weaker in keratinocytes, but more prominent in Langerhans cells. In all sections, toluidine blue-positive mast cells and TA 99-positive basal epidermal melanocytes were the only cells to react with the c-kit antibody. Mastocytomas and urticaria pigmentosa lesions thus exhibit different patterns of stem cell factor expression. However, a possible pathogenetic role of this factor in mastocytosis remains to be determined.

Biphasic Expression of Two Paracrine Melanogenic Cytokines, Stem Cell Factor and Endothelin-1, in Ultraviolet B-Induced Human Melanogenesis

“…Most SCF in human epidermis has been reported to be expressed as the membrane-bound type, which is not released into intercellular spaces between keratinocytes. 66,67 It has also been suggested that the membrane-bound form of SCF is expressed on the plasma membrane of keratinocytes and activates the c-kit receptor persistently without c-kit internalization and degradation within melanocytes. 68 Consistent with this, our previous study on UVB-induced human pigmentation demonstrated that the membrane-bound form, but not the soluble form, of SCF was significantly increased in the UVB-exposed epidermis.…”

Expression of Stem Cell Factor in the Lesional Skin of Systemic Sclerosis

“…Recent studies have indicated that SCF is one of the most important factors influencing the number, phenotype and function of connective tissue type mast cells in health and disease [8, 9, 10]; however, its production and expression in connective tissue diseases have yet to be examined. In this study, we have examined the expression of SCF in the lesional skin of scleroderma by immunohistochemistry to investigate the possible role of SCF in the fibrotic process of scleroderma.…”

Impaired Kit- but Not FcεRI-initiated Mast Cell Activation in the Absence of Phosphoinositide 3-Kinase p85α Gene Products

“…Kit is expressed on both mature MCs and their earliest progenitors (10) as well as on cells of erythroid and melanocytic lineages and on germ cells (11). Kit ligand (KL; also known as stem cell factor), is expressed in membrane-associated and soluble forms (12) by mast cells (13), fibroblasts (11), endothelial cells (14), stromal cells (15), keratinocytes (16), neuroblastoma cells (17), and tumor cell lines (18). Although KL represents a major growth and differentiation factor for both murine and human MCs (19,20), it also promotes Kit-dependent MC mediator release (21)(22)(23), as well as enhances the release of MC mediators via IgE-dependent mechanisms (22,24).…”