T-cell activation differentially mediates the host response to sepsis

Shock. 2010 Oct;34(4):377-83. doi: 10.1097/SHK.0b013e3181dc0845.

Abstract

Survival during sepsis requires both swift control of infectious organisms and tight regulation of the associated inflammatory response. As the role of T cells in sepsis is somewhat controversial, we examined the impact of increasing antigen-dependent activation of CD4 T cells in a murine model of cecal ligation and puncture using T-cell receptor transgenic II (OT-II) mice that are specific for chicken ovalbumin (OVA) in the context of major histocompatibility complex II. Here, we injected OT-II mice with 0, 1, or 100 μg of OVA and demonstrate that increased antigen treatment resulted in increased numbers of activated splenic CD4 T cells. Vehicle-treated, septic OT-II mice had decreased survival, increased bacterial load, and increased levels of IL-6. Interestingly, this decrease in survival was abrogated when OT-II mice were injected with 1 μg OVA, which was correlated with normalized bacterial load and levels of IL-6. However, when OT-II mice were injected with 100 μg OVA, decreased survival was restored but, in contrast to vehicle-treated OT-II mice, had decreased bacterial load and enhanced IL-6 levels. We also observed that neutrophil oxidative burst and phagocytosis were dependent on CD4 T-cell activation. Further, at extreme levels of T-cell activation, intestinal permeability was significantly increased. Altogether, we conclude that too little CD4 T-cell activation produces dysfunctional neutrophils leading to decreased bacteria clearance and survival, whereas too much CD4 T-cell activation produces a neutrophil phenotype that leads to efficient bacterial clearance but with increased tissue damage and mortality.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Blotting, Western
  • CD4-Positive T-Lymphocytes / immunology
  • CD4-Positive T-Lymphocytes / physiology
  • Cells, Cultured
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Flow Cytometry
  • In Vitro Techniques
  • Interleukin-6 / metabolism
  • Lymphocyte Activation / immunology*
  • Lymphocyte Activation / physiology*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Phagocytosis / physiology
  • Respiratory Burst / physiology
  • Sepsis / immunology*

Substances

  • Interleukin-6