House dust mites of the species Dermatophagoides pteronyssinus (Dpt) represent one of the major allergens inducing asthma. However, a strict allergy to Dpt is not always observed in Dpt-allergic patients, since nonallergic and other allergic triggering factors often coexist. It was suggested that specific immunotherapy with house dust-mite extracts is more effective in children than in adults. A controlled study was undertaken in 215 Dpt-allergic patients with asthma ranging in age from 3 to 72 years (mean +/- SD, 28.2 +/- 10.9 years) to investigate parameters that might predict the efficacy of specific immunotherapy before it is started; 171 patients received a rush immunotherapy protocol with a standardized Dpt extract and, subsequently, maintenance injections with 3000 BU of this extract, and 44 patients served as a control group. Before immunotherapy, all patients had a complete evaluation of the severity of asthma by symptom-medication scores and a pulmonary function test, as well as a study of other triggering factors by checking on seasonal and perennial allergens, sinusitis, and other possible causes, such as aspirin intolerance; 196 patients were investigated between 9 and 12 months after the onset of the survey by means of pulmonary function tests and symptom-medication scores. Medications were adapted according to peak flow rates. It was observed that patients with chronic sinusitis, and/or aspirin intolerance, and/or other perennial allergies did not benefit from specific immunotherapy; therefore, the treatment of a major etiologic factor did not demonstrate improvement in the patients.(ABSTRACT TRUNCATED AT 250 WORDS)