PREPARATION AND EFFECTS OF AN ANTI-MAST CELL SERUM.

In an attempt to obtain an antiserum that would bring about widespread destruction of mast cells in the rat, rabbits were immunized with mast cells isolated from the peritoneal cavities of rats. Striking evidence of anti-mast cell activity was indicated in vivo by mast cell disruption and in vitro by positive interfacial precipitin tests of the serum from rabbits so treated. The time course of the production of anti-mast cell activity in the rabbit serum was established. Normal rabbit serum was without effect on mast cells in the several tests. The same was true for rabbit anti-rat liver serum except when it was applied directly to tissues containing mast cells. In the latter case mast cell disruption ensued, but it appeared different from that evoked by anti-mast cell serum. Intraperitoneal injection of anti-mast cell serum was followed by destruction of all of the mast cells of the mesentery and of the majority of mast cells in the ear, scrotum, and abdominal skin. The time course of this destruction, of the phagocytosis of the mast cell debris, and of the repopulation of the tissues with new mast cells was established. Attending the disruption of mast cells the levels of tissue histamine dropped sharply but returned toward normal as new mast cells appeared. In the scrotum and abdominal skin 5-hydroxytryptamine did not fall below normal and was markedly above normal at the time when histamine and mast cell content were lowest. Reddening and swelling of the muzzle, ears, feet, and scrotum were present during the first few days after injection of the anti-mast cell serum. Intraperitoneal injection of normal rabbit serum was without any of the above effects. Similarly injected rabbit anti-rat liver serum had no effect on the mast cells or upon the levels of histamine and 5-hydroxytryptamine in the ear, scrotum, or abdominal skin. It caused no reddening and swelling of the muzzle, ears, feet, and scrotum. It was attended, however, by destruction of the mast cells and by a sharp fall in the histamine content of the mesentery. Gross changes in the tissue of the peritoneal cavity following anti-mast cell and anti-liver serum were described. The possible significance of the several findings were discussed.