Mast cell histamine-releasing activity from stimulated rat neutrophils.

Mast cell histamine-releasing activity (HRA) has been observed in medium derived from stimulated rat neutrophils pretreated with cytochalasin B. This HRA did not require cell-cell contact between mast cells and neutrophils, and its concentration was increased by increasing the number of neutrophils or by raising the concentration of chemotactic peptide used to stimulate the neutrophils. The HRA survived boiling for 5 min and storage overnight at -20 degrees C. In the absence of neutrophil stimulation, no HRA was observed.