Lymph node macrophages: Scavengers, immune sentinels and trophic effectors

Area of Science:

• Immunology
• Cell Biology
• Histology

Background:

• Lymph nodes (LN) are vital secondary lymphoid organs filtering lymph and supporting immune responses.
• Their function relies on a complex stromal microarchitecture involving mesenchymal and vascular components.
• Macrophages (MΦ) within LN possess critical immune and trophic functions.

Purpose of the Study:

• To review macrophage subsets in lymph nodes, focusing on T cell zone MΦ.
• To explore the crosstalk between LN stromal cells and macrophages.
• To propose a model of stromal-macrophage interaction in LN homeostasis and immune responses.

Main Methods:

• Literature review of macrophage subsets in lymph nodes.
• Analysis of interactions between stromal cells and macrophages.
• Synthesis of current knowledge on LN microanatomy and immune cell function.

Main Results:

• Identification and characterization of distinct macrophage subsets in LN.
• Emphasis on the role and characteristics of newly described T cell zone MΦ.
• Evidence suggesting stromal cells create niches supporting macrophage specification, survival, and turnover.

Conclusions:

• Stromal cells and macrophages engage in reciprocal crosstalk within lymph nodes.
• Stromal cells provide essential factors for macrophage maintenance and function.
• Macrophages may modulate LN microanatomy and inform stromal cells about immune status.