ImmunotherapyRole of bacillus Calmette–Guérin as an immunomodulator for the prevention and treatment of allergy and asthmaBarlan, Isil Ba; Bahceciler, Nerina; Akdis, Mübeccelb; Akdis, Cezmi AbAuthor Information aMarmara University Hospital, Pediatric Allergy and Immunology Division, Istanbul, Turkey bSwiss Institute of Allergy and Asthma Research (SIAF), CH-7270 Davos, Switzerland Correspondence to Isil Barlan, MD, Marmara University Hospital, Pediatric Allergy and Immunology Division, 81190 Uskudar, Istanbul, Turkey Tel: +90 216 326 80 30; fax: +90 216 326 80 30; e-mail: [email protected] Sponsorship: The authors’ laboratories are supported by the Swiss National Science Foundation grants: 32-100266, 32-105865, Global Allergy and Asthma European Network (GA2LEN) and Tubıtak grant no. SGAG-1432. Current Opinion in Allergy and Clinical Immunology: December 2005 - Volume 5 - Issue 6 - p 552-557 doi: 10.1097/01.all.0000191238.20632.e2 Buy Metrics Abstract Purpose of review As an essential part of the hygiene hypothesis, the association between exposure to mycobacterial components and the prevention, development and severity of atopic diseases has not been fully understood. The current status on the causal–effect link of this relationship and the potential use of mycobacterial adjuvants as a preventive or disease-modifying modality in allergic diseases is reviewed in this article. Recent findings Data obtained from human and animal models indicate a discrepancy regarding the preventive and therapeutic effect of bacillus Calmette–Guérin in atopic diseases. Among the issues that require clarification include whether the distinction in T helper type 1/2 cells decribed in mice can be fully extrapolated to humans. Other factors involved could be caused by genetic variation, optimal timing, dose, route of delivery as well as environmental factors, which affect the degree of natural exposure to pathogenic or saprophytic mycobacteria. Summary Most of the evidence available to date suggests a need for an improved mycobacterial vaccine administered early in life, by means of alternative routes, preferentially mucosal. As switching away from the T helper type 2 immune response by inducing T helper type 1 is unable to explain the underlying mechanisms of action of mycobacterial antigens, it may be worthwhile to investigate whether T regulatory cells are induced in response to different mycobacterial adjuvants. © 2005 Lippincott Williams & Wilkins, Inc.