Memory Th1 Cells Are Protective in Invasive Staphylococcus aureus Infection

Area of Science:

• Immunology
• Microbiology
• Vaccinology

Background:

• Mechanisms of protective immunity against Staphylococcus aureus (S. aureus) in humans are not well understood.
• While cellular immunity is important in mice, human T cell responses to S. aureus remain uncharacterized.

Purpose of the Study:

• To investigate the role of T helper 1 (Th1) cells in protective immunity against S. aureus.
• To identify potential vaccine targets for S. aureus infection.

Main Methods:

• Utilized a murine model of S. aureus peritonitis to study T cell responses.
• Adoptive transfer of S. aureus antigen-specific Th1 cells in mice.
• Analyzed T cell responses in human patients with S. aureus bloodstream infection (BSI).
• Developed and tested a model vaccine targeting Th1 cells.

Main Results:

• Prior S. aureus exposure enhanced IFNγ responses in mice.
• S. aureus antigen-specific Th1 cells were protective in mice and expanded during human S. aureus BSI.
• These human Th1 cells exhibited a memory phenotype (CD45RO+).
• A model vaccine with staphylococcal clumping factor A and CpG adjuvant induced protection in mice.

Conclusions:

• Exposure to S. aureus induces memory Th1 cells in both mice and humans.
• Th1 cells are potential targets for S. aureus vaccines.
• This study demonstrates a potential correlate of protective immunity transferable from mice to humans.