Effect of ketotifen on antigen-induced interleukin 2 (IL-2) responsiveness in lymphocytes from patients with atopic dermatitis and/or bronchial asthma.

We tested the effect of Ketotifen (4-(1-methyl-4-piperidylidene)-4H- benzo[4,5] cyclohepta[1,2-b]thiophen-10(9H)-one hydrogen (fumarate) on the induction of allergen-induced IL-2 responsiveness in lymphocytes from patients with atopic dermatitis and/or bronchial asthma. Ovalbumin (OVA)- and/or Dermatophagoides farinae(Df)-induced IL-2 responsiveness was increased in almost all patients (1-15 years old) before Ketotifen treatment. Two to 12 months administration of Ketotifen (0.06 mg/kg/day) decreased activity of the response in 7 out of 9 cases corresponding to improvement of clinical symptoms. In in-vitro studies, antigen presenting cells (adherent cells) from the patient pretreated with 5, 50 and 500 ng/ml doses of Ketotifen for 12 h failed to present OVA or Df antigen to T-cells for induction of IL-2 responsiveness. Antigen-pulsed adherent cells also failed to induce the response of the T-cells pretreated with 50 and 500 ng/ml doses of Ketotifen but not with a 5 ng/ml dose. A 50 ng/ml dose of Ketotifen did not affect T-cells for induction of the response. In contrast, the treated adherent cells are capable of presenting PPD antigen or Con A for the induced response. The combined data indicate that induction of IL-2 responsiveness of peripheral blood lymphocytes on stimulation with nominal antigen may reflect an immune response to allergen in patients with allergy and a weak immunosuppressive effect of Ketotifen seems to block the response in the pathogenic process of allergic diseases.