Open Access Research article

Outer membrane protein a of Salmonella enterica serovar Typhimurium activates dendritic cells and enhances Th1 polarization

Jun Sik Lee1, In Duk Jung2, Chang-Min Lee2, Jin Wook Park2, Sung Hak Chun2, Soo Kyung Jeong2, Tae kwun Ha3, Yong Kyoo Shin4, Dae Jin Kim5 and Yeong-Min Park2*

Author Affiliations

1 Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA

2 Department of Microbiology and Immunology & National Research Laboratory of Dendritic Cell Differentiation & Regulation, Pusan National University School of Medicine, Yang-san 626-770, South Korea

3 Department of Surgery, Busan Paik Hospital, Inje University, College of Medicine, Busan, 614-735, South Korea

4 College of Medicine, Chung-Ang University, 221 Heukseok-Dong, Dongjak-Gu, Seoul, Korea

5 Department of Anatomy, College of Medicine, Chung-Ang University, 221 Heukseok-Dong, Dongjak-Gu, Seoul, Korea

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BMC Microbiology 2010, 10:263  doi:10.1186/1471-2180-10-263

Published: 15 October 2010



Typhoid, which is caused by Salmonella enterica serovar Typhimurium, remains a major health concern worldwide. Multidrug-resistant strains of Salmonella have emerged which exhibit increased survivability and virulence, thus leading to increased morbidity. However, little is known about the protective immune response against this microorganism. The outer membrane protein (Omp)A of bacteria plays an important role in pathogenesis.


We purified OmpA from S. enterica serovar Typhimurium (OmpA-sal) and characterized the role of OmpA-sal in promoting adaptive and innate immune responses. OmpA-sal functionally activated bone marrow-derived dendritic cells by augmenting expression of CD80, CD86, and major histocompatibility complex classes I and II. Interestingly, OmpA-sal induced production of interferon-γ from T cells in mixed lymphocyte reactions, thus indicating Th1-polarizing capacity. The expression of surface markers and cytokine production in dendritic cells was mediated by the TLR4 signaling pathway in a TLR4 Knock-out system.


Our findings suggest that OmpA-sal modulates the adaptive immune responses to S. enterica serovar Typhimurium by activating dendritic cells and driving Th1 polarization, which are important properties to consider in the development of effective S. enterica serovar Typhimurium vaccines and immunotherapy adjuvant.