The mechanism of basophil histamine release in patients with periodontal disease.

Histamine release from washed peripheral blood basophils of thirty-three subjects with varying degrees of periodontal disease was studied. Dental plaque, serum and basophil leucocytes were collected from individual patients. There was no histamine release when autologous, washed sonicated plaque was added to leucocytes. However, the incubation of autologous plaque with serum at 37 degrees C for 30 min generated a factor which induced histamine release from basophils. This serum factor was stable to heat (56 degrees C, 30 min), eluted from a Sephadex G-100 column at a volume corresponding to a molecular weight of approximately 16,000 daltons and its action was inhibited by antibody to C5. This factor, therefore, is probably C5a. There was a variation in the degree of histamine release seen with the leucocytes of different donors. This variability was a property of the basophil rather than a function of the serum. Basophils from patients with gingival indices of 0.5 to 1.0 had significantly more histamine release than basophils from patients with gingival indices of less than 0.5 or greater than 1.5 (P less than 0.001). These experiments demonstrate that dental plaque activates serum to form C5a which in turn releases histamine from basophils. However, these experiments do not indicate a role for IgE in this reaction since the direct interaction of plaque with basophils did not cause histamine release. The release of mediators from mast cells could play an important role in the induction of the inflammatory response in periodontal disease.