Histamine release from rat peritoneal mast cells after passive sensitization with human reaginic serum or E myeloma protein

Significant histamine release (HR) (averaging 15 per cent) was attained from rat peritoneal cells upon incubation with human reaginic sera and a specific antigen (grass pollen) or a monospecific anti-IgE antiserum. Similar histamine values were obtained from rat mast cells (RMC) incubated with E myeloma protein and challenged with anti-IgE. Washing the cells after incubation with reaginic serum or E myeloma protein did not result in a decrease in HR upon challenge with grass pollen antigen or anti-IgE. No significant HR was observed in control situations. There was also no significant antigen-induced HR from RMC by nonreaginic (newborn) serum or by reaginic serum that was heated for 4 hours at 56 °C. Furthermore, anti-IgG, -IgA, and -IgM failed to induce HR from RMC incubated with reaginic serum. These observations support the role of human IgE in passive sensitization of heterologous cells (RMC) for the release of a chemical mediator (histamine).