Characterization of the Systemic Loss of Dendritic Cells in Murine Lymph Nodes During Polymicrobial Sepsis

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Abstract
Dendritic cells (DCs) play a key role in critical illness and are depleted in spleens from septic patients and mice. To date, few studies have characterized the systemic effect of sepsis on DC populations in lymphoid tissues. We analyzed the phenotype of DCs and Th cells present in the local (mesenteric) and distant (inguinal and popliteal) lymph nodes of mice with induced polymicrobial sepsis (cecal ligation and puncture). Flow cytometry and immunohistochemical staining demonstrated that there was a significant local (mesenteric nodes) and partial systemic (inguinal, but not popliteal nodes) loss of DCs from lymph nodes in septic mice, and that this process was associated with increased apoptosis. This sepsis-induced loss of DCs occurred after CD3+CD4+ T cell activation and loss in the lymph nodes, and the loss of DCs was not preceded by any sustained increase in their maturation status. In addition, there was no preferential loss of either mature/activated (MHCIIhigh/CD86high) or immature (MHCIIlow/CD86low) DCs during sepsis. However, there was a preferential loss of CD8+ DCs in the local and distant lymph nodes. The loss of DCs in lymphoid tissue, particularly CD8+ lymphoid-derived DCs, may contribute to the alterations in acquired immune status that frequently accompany sepsis.