[Urticaria in relation to mite sensitivity and immunotherapy with Injection dermatophagoidei farinae].

OBJECTIVE: To investigate the prevalence of mite sensitivity in patients with urticaria or other skin rashes, and to observe the clinical efficacy of a specific immunotherapy (SIT) by the Injection dermatophagoides farinae for the patients.

METHODS: In 7-year period (1998-2005), skin prick test (SPT) with a dust mite (Df) allergen was carried out to detect the prevalence of mite sensitivity in OPD patients suffering from skin rashes. Among the patients sensitive to mite with SPT > or =++ response, 3 groups were established. In group A, routine SIT with Injection dermatophagoides farinae was conducted. In 9-week increasing dose phase, three stepwise increasing volumes (0.3 ml, 0.6 ml and 1.0 ml) each case was injected subcutaneously with mite concentration of 1:100000 (w/v), 1:10000 (w/v) or 1:5000 (w/v) respectively once a week, followed by a maintenance dose phase for an injection with 1:5000 (w/v) 1.0 ml/wk for 6 weeks. Group B received rush SIT with mite injections. A total of 15 injections in a course of therapy with same concentration and volume was given as those for the routine ones except shortened intervals, namely, 9 initial injections completed in 3 days by three injections of each concentration per day with two 30 min intervals, maintenance doses were then provided in 6 days with 1:5000 (w/v) 1.0 ml/d. Thereafter, both groups A and B were maintained for one year with a dose of 1:5000 (w/v) 1.0 ml every 2 wk. Group C received antihistamine treatment as control, the patients received daily oral Ebastine 10 mg in the morning and Cetirizine dihydrochloride 10 mg in the evening for one week course and pro re nata later. Levels of serum tIgE and serum mite sIgE were detected by ELISA in 20 urticaria cases before and after one year mite SIT.

RESULTS: Altogether, 2685 cases with skin rashes were detected by Df allergen SPT. The prevalence of urticaria cases sensitive to mite was 70.3% (1754/2496), which was higher than that of eczema 63.5% (54/85) and anaphylactoid purpura 60.6% (63/104) (P < 0.05) . 248 cases of urticaria sensitive to mite with SPT > or = ++ response received SIT with Injection dermatophagoides farinae for one year, clinical evaluation revealed an overall efficacy of 91.1% (226/248) with 66.1% (164/248) of excellent or good results, significantly higher than that of antihistamine treatment [12.7% (20/158)] (P < 0.01). Faster improvement of clinical symptoms was shown in rush SIT (group B) than that of routine one (group A), with higher efficacy in group B than group A (excellent and good results being 76.7% and 55.0% respectively) (P < 0.05). Serum tIgE and mite sIgE in 20 urticaria cases were detected before and after one year mite SIT, showing that tIgE decreased by half in 40% (8) of the patients, while serum mite sIgE level increased significantly (P < 0.01) one year later.

CONCLUSION: Mite allergen SPT is an etiological diagnostic technique for urticaria patients sensitive to mite. Clinical efficacy of mite allergen SIT has been proved to be good for the patients, and the rush SIT shows quicker effect of relieving symptoms and better efficacy than that of the routine immunotherapy.