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pubmed:abstractText |
Major histocompatibility complex (MHC) class Ib molecules have been implicated in CD8(+) T cell-mediated defenses against intracellular bacterial infection, but the relative importance of MHC class Ib-restricted T cells in antimicrobial immunity is unknown. In this report, we use MHC tetramers to characterize T cell responses restricted by H2-M3, an MHC class Ib molecule that selectively presents N-formyl peptides. We find that sizeable H2-M3-restricted T cell responses, occurring earlier than MHC class Ia-restricted T cell responses, are mounted after primary infection with the intracellular bacterium Listeria monocytogenes. These H2-M3-restricted T cells are cytolytic and produce interferon gamma. However, after a second L. monocytogenes infection, H2-M3-restricted memory T cell responses are minor in comparison to the much larger MHC class Ia-restricted responses. This first direct characterization of an MHC class Ib-restricted T cell response indicates that CD8(+) T cells responding to L. monocytogenes infection can be divided into two groups: H2-M3-restricted responses, which provide rapid and quantitatively substantial effector function during primary infections but contribute relatively little to memory responses, and MHC class Ia-restricted responses, which expand later during primary infection but form memory T cells that respond rapidly and dramatically in response to subsequent infections by the same pathogen.
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pubmed:publicationType |
Journal Article,
Comparative Study,
In Vitro,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
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