In vitro releasability of histamine and serotonin: studies of atopic patients.

Sixteen atopic patients with anaphylaxis to food, eczema, asthma and/or rhinitis were investigated for in vitro reactivity of their leukocytes and platelets to various stimuli. Leukocytes from two patients with anaphylaxis to foods had very high spontaneous release of histamine. Compared to non-atopic volunteers without respiratory disease, leukocytes from the other atopic patients showed increased histamine release after stimulation with methacholine in concentrations between 10(-2) and 10(-6) M. Histamine release induced by anti-IgE or anti-kappa chain serum was slightly decreased in atopics compared to controls, and was significantly decreased at low concentrations of anti-IgE (p less than 0.05). There was no significant difference of means for histamine release induced by the calcium ionophore A-23815. The uptake of 3H serotonin from platelet-rich plasma of atopic patients appeared to occur more slowly than in non-atopics. Serotonin release from washed platelets after stimulation with aggregated IgG was significantly lower in the atopic group (p less than 0.01). There was no significant difference in serotonin release induced by thrombin, epinephrine, ionophore or methacholine. Alterations in releasability of mediator containing cells to immunologic and non-immunologic stimuli may play a role in the expression of atopic disease.