Immunohistochemical Characterization of Human Cutaneous Mast Cells in Urticaria Pigmentosa (Cutaneous Mastocytosis)

Abstract

To clarify the origin and function of human cutaneous mast cells (CMCs), immunohistochemical characterization was done in 19 cases of urticaria pigmentosa (cutaneous mastocytosis) using 9 antibodies (anti leukocyte common antigen, MX‐PanB, anti lysozyme, anti α1, antitrypsin, anti α1‐antichymotrypsin, anti vimentin, anti‐neuron specific enolase, anti factor VIII related antigen, and anti‐ACTH). CMCs showed positive reactions with anti α1 anti‐chymotrypsin and anti vimentin in almost all of the specimens. In more than half of the specimens, CMCs were stained positively with anti ‐α1‐antitrypsin, MX‐PanB, and anti factor VIII related antigen. Anti‐leukocyte common antigen and anti ACTH also showed positive reactions in some specimens. These results confirm the existence of vimentin filaments in CMCs and suggest a functional role of CMCs in hemostasis via factor VIII. Furthermore, immunohistochemical similarity between CMCs and granulocyte/macrophage group cells is also suggested.

Immunoreactivity of Human Tissue Mast Cells

“…sin, alpha,-antichymotrypsin, and lysozyme observed by Akayima et a/. (1) should, according to the results of our control investigations, be regarded as specific, and reflects the close relationship o f mast cells t o bone marrow cells, particularly cells o f the myelomonocytic lineage. Our more recent investigations have shown that the antibodies K P 1 and K i M l P , which also detect macrophage-associated antigens (6, 7), also react with neoplastic and non-neoplastic mast cells.…”

The release of histamine is associated with the inactivation of mast cell chymase during immediate allergic wheal reaction in the skin

“…Gradually reduced chymase activity has been observed during the evolvement of psoriasis, herpes zoster and blistering skin diseases, which could mostly be due to increased levels of chymase inhibitors, α 1 ‐AC and α 1 ‐PI, in the same mast cells [16–19]. It is not known whether mast cells can synthesize these inhibitors or whether they are derived from blood circulation, but the staining pattern of α 1 ‐AC and α 1 ‐PI in mast cells is granular, suggesting their localization in secretory granules [26]. Recently, human mast cells have been shown to produce secretory leucocyte protease inhibitor (SLPI) that can also inhibit chymase [27].…”

Decreased Chymase Activity is Associated with Increased Levels of Protease Inhibitors in Mast Cells of Psoriatic Lesions

“…In fact, the cytoplasmic staining of these inhibitors in mast cells has been shown to be intense and granular in formalin-¢xed and para¤n-embedded skin specimens (35,36), supporting the assumption that mast cells have the capability to synthesize and store these substances in their secretory granules. However, serum contains high levels of a 1 -PI and a 1 -AC which could di¡use from circulation and bind to their counterpart proteinases exposed to the extracellular environment after mast cell degranulation.…”