Immunohistochemical characterization of human cutaneous mast cells in urticaria pigmentosa (cutaneous mastocytosis).

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- alpha 1-antitrypsin, anti- alpha 1-antichymotrypsin, anti-vimentin, anti-neuron-specific enolase, anti-factor VIII-related antigen, and anti-ACTH). CMCs showed positive reactions with anti-alpha 1-antichymotrypsin and anti-vimentin in almost all of the specimens. In more than half of the specimens, CMCs were stained positively with anti-alpha 1-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.