1Department of Immunology and Bronchial Asthma Research Unit, Medical Research Institute, University of Alexandria, Egypt and ²Department of Immunology, Rheumatism and Allergy Research Unit, Medical School University of Birmingham. UK.

Elastase enzyme from porcine pancreas has induced the release of significant amounts of histamine from percoll-purifed rat peritoneal mast cells in a concentration-dependent fashion. pre-incubation with alpha-1-proteinase inhibitor (a .1.PI.) has failed to inhibit this activity of the enzyme. A role for this enzyme in bronchial hyperresponsiveness in obstructive airway diseases is suggested. The use of elastase in tissue processing techniques of tissues poor in macrophages such as human tonsils might adversely influence mast cells secretory responses to both immunologic and non-immunologic stimuli.