Yates JL, Racine R, McBride KM, Winslow GM. T cell-dependent IgM memory B cells generated during bacterial infection are required for IgG responses to antigen challenge.
J Immunol 2013;
191:1240-9. [PMID:
23804710 PMCID:
PMC3720767 DOI:
10.4049/jimmunol.1300062]
[Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Immunological memory has long considered to be harbored in B cells that express high-affinity class-switched IgG. IgM-positive memory B cells can also be generated following immunization, although their physiological role has been unclear. In this study, we show that bacterial infection elicited a relatively large population of IgM memory B cells that were uniquely identified by their surface expression of CD11c, CD73, and programmed death-ligand 2. The cells lacked expression of cell surface markers typically expressed by germinal center B cells, were CD138 negative, and did not secrete Ab ex vivo. The population was also largely quiescent and accumulated somatic mutations. The IgM memory B cells were located in the region of the splenic marginal zone and were not detected in blood or other secondary lymphoid organs. Generation of the memory cells was CD4 T cell dependent and required IL-21R signaling. In vivo depletion of the IgM memory B cells abrogated the IgG recall responses to specific Ag challenge, demonstrating that the cell population was required for humoral memory, and underwent class-switch recombination following Ag encounter. Our findings demonstrate that T cell-dependent IgM memory B cells can be elicited at high frequency and can play an important role in maintaining long-term immunity during bacterial infection.
Collapse