The aim of the study is to assess the safety and efficacy of sublingual immunotherapy applied preseasonal and seasonal in ultra-rush scheme in children with bronchial asthma allergic to grass pollen. The investigators will assess clinical symptoms, reliever drugs usage, lung function, chosen markers of allergic inflammation, bronchial hyperreactivity with methacholine, and presence and type of allergy after two years of sublingual immunotherapy (SLIT) in children with asthma.