Potentiation of antigen-induced histamine release from rat peritoneal mast cells through a direct interaction between mast cells and non-mast cells

Abstract

Rat peritoneal mast cells, which had been sensitized two days earlier by an intraperitoneal injection of rat monoclonal IgE antibodies, were purified by density gradient centrifugation with 60% Percoll (cell purity >;95%). Histamine release from the purified mast cells (PMC) was then compared to that of a non-purified preparation (peritoneal exudate cells; PEC). Both PEC and PMC released similar amounts of histamine upon stimulation with calcium ionophore A23187 and compound 48/80. In contrast, antigen-induced histamine release from PMC was very low compared to that of PEC. PEC released up to 30% of total histamine upon challenge with 1 μg/ml of antigen, whereas histamine release from PMC was only one third or less than that of PEC. When PEC was suspended in 60% Percoll and treated for a period needed for purification, the reduction of antigen-induced histamine release was negligible. Mast cells purified by centrifugation on a metrizamide gradient released only small amount of histamine similar to Percoll-purified mast cells. Non-mast cells (NMC) recovered from the interface of the 60% Percoll potentiated the antigen-induced histamine release from PMC concentration- and time-dependently. The supernatant of the NMC suspension which was incubated at 37 °C for 60 min, however, failed to potentiate histamine release in PMC. We concluded therefore that separation media such as Percoll and metrizamide do not cause the low antigen-induced histamine release in PMC, but that the separation of mast cells from other cells present in the peritoneal cavity itself causes it. Antigen-induced mast cell histamine release is potentiated through a direct interaction between mast cells and NMC, and some cell surface molecules also seem to be involved.