Keywords: immunostimulants, action mechanisms, acute respiratory tract infections, ARTIs, chronic obstructive pulmonary diseases, COPD, clinical trials, immunomodulation, prophylactic modality, therapeutic modality, respiratory infections, bacterial lysates
Immunostimulants in the prevention of respiratory infections
Immunomodulation promises to be an effective prophylactic and therapeutic modality for chronic and recurrent respiratory infections. As opposed to vaccines, the term Immunostimulant (IS) refers to a compound that produces a state of non-specific immunity. Most IS are oral formulations of bacterial lysates that have been used in clinical practice for decades. One of the main obstacles in the development of immunostimulants is the poor understanding of the mechanism of action. Except for some compounds the mechanism of action of bacterial products is not well understood. Some appear to act through activation of monocytic cells and macrophages and enhancement of polyclonal proliferation of B cells. In general, the use of IS results in beneficial clinical outcome but the quality of some clinical trials for preventing Acute Respiratory Tract Infections (ARTIs) must be improved. In pediatric population the use of IS for the prevention of ARTIs needs to be limited to children with high susceptibility to ARTIs or overexposed children, while in adults it must be indicated for patients with Chronic Obstructive Pulmonary Diseases (COPD) at high risk of exacerbation.