1. Department of Immunology and Infectious Diseases; The Forsyth Institute; 245 First Street Cambridge Massachusetts 02142 USA
2. Department of Periodontology; Peking University School and Hospital of Stomatology; 22 Zhong-Guan-Cun South Avenue Beijing 100081
3. Department of Stomatology; Fourth Hospital of Harbin Medical University; 37 Yinhang Street Harbin 150001 China