Desensitization of rat mast cells: studies of some effects of anti-allergic drugs.

Peritoneal mast cells from rats immunized with dinitrophenylated ovalbumin (DNP-OA) or normal cells passively sensitized with mouse anti-DNP-OA were incubated in vitro with DNP-bovine serum albumin in the absence of Ca++. This procedure induced desensitization of the cells, such that histamine release was inhibited on subsequent challenge with OA, in the presence of Ca++. The phenomenon of desensitization is supposed to involve early stages in the histamine release process and, thus, two anti-allergic drugs, disodium cromoglycate and doxantrazole, which inhibit an early event(s), were added with the Ca++ -free antigen to investigate whether they had any effect on desensitization. The inhibition of final histamine release caused by each drug and that due to desensitization were approximately additive. It was concluded that the drugs did not influence desensitization of rat mast cells. Thus, their activity was consistent with an effect on an event in the histamine release process, occurring after the generation of the activated stage believed to be responsible for desensitization.