An investigation of the optimal conditions for the in vivo production of immunologically sensitised rat mast cells.

Experiments were designed to develop an optimal method for inducing in vivo production of sensitised peritoneal mast cells. Rats of different strains were sensitised with whole egg-white and killed at suitable intervals to harvest the peritoneal mast cells. Release of histamine was induced in vitro by both whole egg-white and its major protein constituents, and assayed by a standard spectrofluorometric method. Wistar rats showed higher levels of sensitisation than black-hooded Lister rats; it was more convenient to harvest erythrocyte-free peritoneal mast cells from males than females. Very young (less than 150 g) and very old (greater than 300 g) rats showed sub-optimal sensitisation. Optimal sensitisation was obtained by simultaneous administration of antigen (doses of 50 micrograms whole egg-white and above) and adjuvant (1.0 ml pertussis vaccine); mast cells harvested between 20 and 50 days after the sensitising dose exhibited maximal histamine release upon in vitro challenge with 'whole' egg-white (100 micrograms). Routine use of plastic ware, and ice-cold phosphate-buffered saline (pH 7.2) for handling cells and avoidance of heparin and excessive centrifugation ensured optimal preservation of histamine-releasing capacity of the harvested peritoneal mast cells.