Methotrexate in autoimmune urticaria

Sir,

Chronic idiopathic urticaria may be autoimmune in origin (autoimmune urticaria), caused by functional autoantibodies that activate mast cells and basophils through cross linking the high affinity IgE receptor (Fc RI ) to secrete histamine.[1] An incidence of 30% to 50% has been reported by various investigators.[1] While there are no clinical features that distinguish ordinary urticaria from autoimmune urticaria, a simple test, the autologous serum skin test, can be used to detect functional autoantibodies. Patients with autoimmune urticaria whose disease is pursuing a severe disabling and recalcitrant course have been treated with immunosuppressive therapy, including cyclosporine.[2] However, its high cost makes this drug an impractical option in India. Gach et al successfully tried methotrexate in two patients without detectable autoantibodies and in whom steroids and antihistamines were not effective.[3] However, there are no randomized controlled studies of the use of methotrexate in patients with autoimmune urticaria.[4] We report our preliminary experience of using methotrexate in four patients with autoimmune urticaria.

We tested 45 patients (age ranging from 15 to 55 years) with chronic idiopathic urticaria with the autologous serum skin test for autoantibodies. Twelve of them showed a positive result, including four (3 females and 1 male) who were recalcitrant to treatment with oral antihistamines (fexofenadine, cetirizine, hydroxyzine). After performing baseline investigations (complete blood count, random blood sugar, SGPT, and urine examination), we tried methotrexate in these patients with autoimmune urticaria in a dose of 2.5 mg orally twice a day on Saturday and Sunday of every week. Informed consent was taken before starting methotrexate. In addition, cetirizine 10 mg and folic acid 1.5 mg were given daily. All four patients showed a remarkable effect in the form of reduction in whealing and itching in one month. Investigations were repeated after one month for monitoring of side effects. Treatment with methotrexate was continued for 2 months and later only cetirizine was continued. One patient developed a relapse within two weeks of stopping methotrexate and was again started on methotrexate.

All the four patients had troublesome urticaria that was difficult to control with antihistamines alone. After a course of methotrexate the urticaria was controllable with cetirizine in three patients. In India methotrexate has the potential of being a viable option for the treatment of resistant autoimmune urticaria as it is cost effective and most dermatologists have the experience of using it for psoriasis. A larger controlled study needs to be undertaken to confirm these preliminary findings.