Antigen-specific B cells reactivate an effective cytotoxic T cell response against phagocytosed Salmonella through cross-presentation.
BACKGROUND
The eradication of facultative intracellular bacterial pathogens, like Salmonella typhi, requires the concerted action of both the humoral immune response and the cytotoxic CD8(+) T cell response. Dendritic cells (DCs) are considered to orchestrate the cytotoxic CD8(+) T cell response via cross-presentation of bacterial antigens onto MHC class I molecules. Cross-presentation of Salmonella by DCs however, is accompanied by the induction of apoptosis in the DCs. Besides antibody production, B cells are required to clear Salmonella infection for other unknown reasons.


RESULTS
Here we show that Salmonella-specific B cells that phagocytose Salmonella upon BCR-ligation reactivate human memory CD8(+) T cells via cross-presentation yielding a Salmonella-specific cytotoxic T cell response. The reactivation of CD8(+) T cells is dependent on CD4(+) T cell help. Unlike the DCs, B cell-mediated cross-presentation of Salmonella does not coincide with apoptosis.


CONCLUSIONS
B cells form a new player in the activation of the cytotoxic effector arm of the immune response and the generation of effective adaptive immunity in Salmonella infection.
de Wit
Jelle
J
Sanquin Research and Landsteiner Laboratory, Department of Immunopathology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Souwer
Yuri
Y
Jorritsma
Tineke
T
Klaasse Bos
Hanny
H
ten Brinke
Anja
A
Neefjes
Jacques
J
van Ham
S Marieke
SM
D017951:Antigen Presentation; D000942:Antigens, Bacterial / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology* / Q000382:microbiology; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000276:immunology; D006801:Humans; D008213:Lymphocyte Activation; D010587:Phagocytosis; D012480:Salmonella Infections / Q000276:immunology* / Q000382:microbiology; D012486:Salmonella typhimurium / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D000942:Antigens, Bacterial