ARTICLES response through the oral delivery of bacterial extracts. This procedure is a common practice in Europe to reduce the clinical symptoms, the incidence, the duration, and the severity of disease in patients suffering from recurrent respiratory infections. 11,12 According to the concept of " common mucosal immune system, " presentation of an antigen at one mucosal site leads to the stimulation of an immune response at a distant mucosal site. Similarly, oral treatment with bacterial extracts modulates both systemic and local immune responses. 13 However, the mechanisms underlying the immunostimulatory effect of these bacterial extracts via the gastrointestinal route remain unclear. Broncho-Vaxom (BV) is an endotoxin-low, lyophilized fractionated alkaline extract of the following eight bacterial strains: Haemophilus influenzae , Diplococcus pneumonia , Klebsiella pneumoniae , Klebsiella ozaenae , Staphylococcus aureus , Streptococcus pyogenes , Streptococcus viridans , and Neisseria catarrhalis. It has been widely used in children and adults suffering from repeated upper respiratory tract infections, 14-16 and it efficiently reduces both the frequency and the duration of the infections. 12 In the present report, we have investigated the effect of oral BV administration in the development of allergic airway inflammation. To this aim, BALB / c mice were treated with BV orally, and subsequently sensitized and challenged with the Leishmania homolog of receptors for activated c kinase (LACK) antigen 17 or with the commonly used OVA antigen. RESULTS Oral administration of BV protects mice from allergic airway inflammation