Our findings demonstrate that Broncho-Vaxom (BV) displays possibly via the gut-associated immune system different effects on the lymphatic system of the lung: a positive influence on the helper/suppressor T-lymphocyte balance, an increase of γ interferon, a stimulation of the reduced alveolar macrophage activity, and a regulation of BAL IgA to a distinct level whereby the serum IgE is reduced. By these effects BV is able to modulate impaired local and systemic immune function. The observed relationship between the inflammation score and the BAL fluid composition supports the view that the improvement of the mucosa lesion found in nearly all of our patients with chronic bronchitis occurs as the result of the pleiotropic immunomodulating effects of Broncho-Vaxom.