Human-IgE-induced degranulation of mouse mast cells.

The relations between human IgE and mouse peritoneal mast cells were studied in vitro. Non-heated human IgE sensitizes the mouse mast cells for degranulation on challenge with anti-human IgE. This capacity is lost after heating of human IgE at 56 degrees C. The degranulation only occurs in determined quantitative IgE-anti-IgE relationships, an excess of one or the other reagent inhibiting the reaction. Sensitization is practically instanteneous, and the degranulation is independent on the order of addition of the human IgE and anti-IgE. The human IgE can be removed from mouse peritoneal mast cells by a single washing. The results show that human IgE is unable to bind firmly to mouse peritoneal mast cells in vitro. It seems to induce the formation of biologically active human IgE-anti-human IgE complexes, which act on mouse mast cells and induce their degranulation.