Km. Kerksiek et al., H2-M3-restricted T cells in bacterial infection: Rapid primary but diminished memory responses, J EXP MED, 190(2), 1999, pp. 195-204
Major histocompatibility complex (MHC) class Ib molecules have been implica
ted in CD8(+) T cell-mediated defenses against intracellular bacterial infe
ction, but the relative importance of MHC class Ib-restricted T cells in an
timicrobial immunity is unknown. In this report, we use MHC tetramers to ch
aracterize T cell responses restricted by H2-M3, an MHC class Ib molecule t
hat selectively presents N-formyl peptides. We find that sizeable H2-M3-res
tricted 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 cytoly
tic 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 ch
aracterization of an MHC class Ib-restricted T cell response indicates that
CD8(+) T cells responding to L. monocytogenes infection can be divided int
o two groups: H2-M3-restricted responses, which provide rapid and quantitat
ively substantial effector function during primary infections but contribut
e relatively Little to memory responses, and MHC class Ia-restricted respon
ses, which expand later during primary infection but form memory T cells th
at respond rapidly and dramatically in response to subsequent infections by
the same pathogen.