HISTOCHEMICAL STUDIES ON THE ROLE OF THE MAST CELL IN CALCERGY

Experiments were performed on rats, using special histochemical stains for the demonstration of metachromatic materials, lead, calcium, phosphate and carbonate, to study calcergy, the induction of soft-tissue calcification by topical treatment with certain compounds such as lead acetate. In simple calcergy, when lead acetate is directly injected into the subcutis, it is seen to impregnate the collagen fibers in the injection site without noteworthy participation of the mast cells. The lead-treated area secondarily attracts calcium, phosphate and possibly carbonate. In mastocalcergy, the lead acetate is injected intravenously and local calcification is produced by the simultaneous subcutaneous injection of a mast-cell discharger such as polymyxin. Here, the mast cells in the treated area first show degranulation without any mineralization, but this is soon followed by lead uptake on the mast-cell granules with secondary attraction of calcium, phosphate and possibly carbonate. Finally, the discharged and calcified mast-cell granules disintegrate into a dustlike, fine precipitate which is transferred to the circumjacent collagen fibers where it initiates an intense process of mineralization, eventually leading to the complete petrification of the polymyxin-injected area. Apparently, in addition to its already well established functions of histamine, heparin and serotonin production, the mast cell also plays a role in mineralization.