Localization of macrophages and dendritic cells in human thoracic lymph nodes: An immunohistochemical study using
Masaya Aoki1, Zhe-Wu Jin2, Kazuhiro Ueda1
1Department of General Thoracic Surgery, Kagoshima University School of Medicine, Kagoshima, Japan.
Insights
Dendritic cells (DCs) form distinct clusters and rosettes in human lymph nodes, largely separate from macrophages. This unique distribution suggests limited cooperation between these antigen-presenting cells in humans.
Area of Science:
- Immunology
- Cell Biology
- Oncology
Background:
- Dendritic cells (DCs) and macrophages are critical bone marrow-derived antigen-presenting cells.
- Understanding their distribution in lymph nodes is key to immune response comprehension.
- Previous knowledge on human lymph node architecture regarding these cells is limited.
Purpose of the Study:
- To investigate the distribution of dendritic cells (DCs) and macrophages in human thoracic lymph nodes.
- To compare DC and macrophage distribution in lymph nodes from patients without metastasis versus those with metastasis.
- To elucidate potential interactions and cooperation between DCs and macrophages in the human lymph node microenvironment.
Main Methods:
- Immunohistochemical analysis of 103 thoracic lymph nodes from 23 lung cancer patients without metastasis.
- Utilized CD209/DCsign as the primary marker for dendritic cells (DCs).
- Examined 137 lymph nodes from 12 patients with cancer metastasis for comparative histological analysis.
Main Results:
- Dendritic cells (DCs) were identified in distinct clusters along the subcapsular sinus and in rosette-like structures within the cortex.
- These DC clusters and rosettes were predominantly devoid of macrophages and bordered by smooth muscle actin (SMA)-positive cells.
- Subcapsular DC clusters were shorter in older patients, and while generally distinct, sometimes contained macrophages in metastasis cases.
Conclusions:
- Human lymph nodes exhibit a unique distribution of dendritic cells (DCs) in specific clusters and rosettes, unlike rodent models.
- The spatial segregation of DCs and macrophages suggests limited functional cooperation between these cell types in humans.
- Findings highlight distinct immune cell organization in human lymph nodes, potentially impacting antigen presentation and immune surveillance.
Abstract:
Both dendritic cells (DCs) and macrophages are bone marrow-derived cells that perform antigen presentation. The distribution of DCs and CD68-positive macrophages were immunohistochemically examined in 103 thoracic nodes obtained from 23 lung cancer patients (50-84 years old) without metastasis. Among three antibodies tested initially-CD209/DCsign, fascin, and CD83-DCsign was chosen as the DC marker. For comparison, 137 nodes from 12 patients with cancer metastasis were also examined histologically. In patients without metastasis, DCs were found as (1) clusters along the subcapsular sinus and in a border area between the medullary sinus and cortex (mean sectional area of multiple nodes at one site, 8.4%) and, (2) rosette-like structures in the cortex (mean number in multiple nodes at one site, 20.5). Notably, DC clusters and rosettes contained no or few macrophages and were surrounded by smooth muscle actin (SMA)-positive, endothelium-like cells. The subcapsular linear cluster corresponded to 5%-85% (mean, 34.0%) of the nodal circumferential length and was shorter in older patients (p = 0.009). DC rosettes, solitary, or communicating with a cluster, were usually connected to a paracortical lymph sinus. Few differences were found between nodes with or without metastasis, but DC cluster sometimes contained abundant macrophages in cancer metastasis patients. The subcapsular DC cluster is not known in the rodent model, in which the subcapsular sinus is filled with macrophages. This quite different, even complementary, distribution suggests no, or less, cooperation between DCs and macrophages in humans.
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