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Macrophage precursor cells produce perforin and perform Yac-1 lytic activity in response to stimulation with
1Department of Immunobiology, Fraunhofer Institute of Toxicology, Hannover, Germany.
Abstract:
Macrophage precursor cells, derived from mouse bone marrow culture with granulocyte-macrophage colony-stimulating factor or colony-stimulating factor 1 (CSF-1) as growth factor and interleukin-2 (IL-2) as stimulating factor, were activated by IL-2 to exert strong cytolytic activity against Yac-1 cells. In response to IL-2 stimulation these bone marrow macrophage precursor cells produced perforin as lytic molecules. The purity of the precursor cells for the study was proved as homogeneous positivity for Mac-1, NK-1.1 and negativity for Lyt 1 and 2. The cells express CSF-1 receptors on their surface, are able to proliferate and differentiate into typical macrophages when stimulated with CSF-1, and are therefore members of the macrophage lineage. Perforin transcripts were identified by Northern blot analysis of IL-2-treated macrophage precursor cells, and the presence of perforin protein in the cytoplasmic granules was demonstrated by immunohistochemical staining using a monoclonal antiperforin antibody. In addition, the biological activity of the perforin contained in the macrophage precursor's granules could be documented as calcium-dependent lytic activity using Yac-1 and sheep red blood cells as targets. The results presented in this paper imply the existence of a bipotent precursor cell, which can mature into a typical macrophage if CSF-1 or phorbol 12-myristate 13-acetate is supplied as differentiation stimulating factor but develops into an NK/LAK cell when early activation with IL-2 is provided.
Insights
Mouse bone marrow cells activated by interleukin-2 (IL-2) develop cytotoxic activity and produce perforin. These macrophage precursors differentiate into macrophages with CSF-1 or NK/LAK cells with IL-2.
Area of Science:
- Immunology
- Cell Biology
- Hematopoiesis
Background:
- Macrophage precursor cells are crucial for immune responses.
- Interleukin-2 (IL-2) and Colony-Stimulating Factor 1 (CSF-1) are key regulators of myeloid cell development.
- Natural Killer (NK) and Lymphokine-Activated Killer (LAK) cells possess cytotoxic functions.
Purpose of the Study:
- To investigate the differentiation potential of macrophage precursor cells.
- To determine the role of IL-2 in activating cytotoxic activity in these precursors.
- To identify the molecules responsible for IL-2-induced cytotoxicity.
Main Methods:
- Bone marrow-derived macrophage precursor cell culture.
- Stimulation with IL-2 and CSF-1.
- Flow cytometry for cell surface marker analysis (Mac-1, NK-1.1, Lyt 1, Lyt 2, CSF-1 receptor).
- Northern blot analysis for perforin gene expression.
- Immunohistochemistry for perforin protein detection.
- Functional assays for cytotoxic activity (calcium-dependent lysis).
Main Results:
- IL-2 stimulation induced potent cytolytic activity in macrophage precursors against Yac-1 cells.
- These activated precursors produced perforin, a key cytotoxic molecule.
- Cells expressed Mac-1, NK-1.1, and CSF-1 receptors, confirming macrophage lineage and NK/LAK potential.
- Perforin transcripts and protein were detected in IL-2-stimulated cells.
- Calcium-dependent cytotoxic activity was confirmed.
Conclusions:
- Macrophage precursor cells exhibit bipotent differentiation potential.
- Early activation with IL-2 drives differentiation towards NK/LAK-like cytotoxic cells.
- CSF-1 promotes differentiation into typical macrophages.
- Perforin is the primary mediator of IL-2-induced cytotoxicity in these cells.