Related Experiment Video
Updated: May 3, 2026
Isolation and Activation of Murine Lymphocytes
Published on: October 30, 2016
Brief report: alternative activation of laser-captured murine hemophagocytes
Objective:
Hemophagocytes (HPCs) are activated macrophages that have engulfed other hematopoietic cells. Although HPCs are rarely identified in normal spleen tissue and bone marrow, an excess of these macrophages characterizes many cytokine storm syndromes, particularly macrophage activation syndrome and hemophagocytic lymphohistiocytosis. This study was undertaken to assess the functions of HPCs and their significance in acute inflammatory conditions.
Methods:
HPCs were generated in wild-type mice using repeated stimulation with Toll-like receptor 9 (TLR-9) and interleukin-10 receptor blockade. RNA was extracted from HPCs that had been isolated by lasercaptured microdissection. Transcriptional profiles of the HPCs were then compared to those of resting splenic macrophages. In addition, bone marrow samples were obtained from a diverse cohort of patients in whom excess hemophagocytosis was identified by clinical bone marrow biopsy or aspiration. The bone marrow samples were analyzed by immunohistochemistry for markers of classic (CD64) or alternative (CD163 and CD206) macrophage activation.
Results:
Differential gene expression and gene set enrichment analyses of murine HPCs identified upregulation of genes and gene sets associated with alternative activation of HPCs. Immunohistochemical analyses of HPCs in human bone marrow samples showed universal staining of HPCs for CD163, but rarely for CD206 or CD64.
Conclusion:
Laser-captured murine TLR-9– induced HPCs had a transcriptional profile similar to that of alternatively activated macrophages. In addition, HPC expression of CD163 was confirmed in a uniquely diverse cohort of patients with hemophagocytic syndromes. Collectively, these data support the hypothesis that HPCs have both immunoregulatory and clean-up functions.
Insights
Hemophagocytes (HPCs), activated macrophages engulfing cells, play key roles in inflammatory conditions. This study reveals HPCs exhibit alternative activation markers and possess immunoregulatory functions.
Area of Science:
- Immunology
- Cell Biology
- Pathology
Background:
- Hemophagocytes (HPCs) are activated macrophages that engulf hematopoietic cells.
- HPCs are rarely found in normal tissues but are abundant in cytokine storm syndromes like macrophage activation syndrome and hemophagocytic lymphohistiocytosis.
- The precise functions of HPCs in acute inflammation remain to be fully elucidated.
Purpose of the Study:
- To investigate the functions of hemophagocytes (HPCs).
- To assess the significance of HPCs in acute inflammatory conditions.
- To characterize the transcriptional profile and activation markers of HPCs.
Main Methods:
- HPCs were generated in mice via Toll-like receptor 9 (TLR-9) stimulation and IL-10 receptor blockade.
- RNA sequencing and laser-captured microdissection were used to analyze HPC gene expression.
- Human bone marrow samples from patients with hemophagocytosis were analyzed for macrophage activation markers (CD64, CD163, CD206) via immunohistochemistry.
Main Results:
- Murine HPCs showed upregulated genes and pathways associated with alternative macrophage activation.
- Human HPCs universally expressed CD163, a marker of alternative activation, but rarely expressed CD64 or CD206.
- Transcriptional profiles of laser-captured murine HPCs resembled alternatively activated macrophages.
Conclusions:
- Hemophagocytes (HPCs) induced by TLR-9 stimulation exhibit a transcriptional profile consistent with alternatively activated macrophages.
- CD163 expression on HPCs was confirmed in human patients with hemophagocytic syndromes.
- These findings support the hypothesis that HPCs perform both immunoregulatory and cellular clean-up functions in inflammatory conditions.
