A mononuclear cell derived histamine releasing factor (HRF) in asthmatic patients. Histamine release from basophils in vitro.

Mononuclear cells from asthmatic patients produced a histamine releasing factor (HRF). Mononuclear cells produced this factor in culture spontaneously but significantly much more following specific allergen stimulation. This factor released histamine from both sensitized and unsensitized basophils in vitro. Mononuclear cells from healthy subjects produced HRF only after nonspecific mitogen/phytohemagglutinin stimulation. Asthmatic patients on immunotherapy with essential benefits failed to produce HRF.