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Cell contact and direct transfer between co-cultured macrophages and fibroblasts
M F Dean1, J A Cooper, P Stahl
1Department of Biochemistry, Kennedy Institute of Rheumatology, London, England.
Abstract:
Mouse peritoneal macrophages formed attachments with beta-glucuronidase deficient human fibroblasts within an hour after co-cultures were initiated. Some of these attachments were transitory, while in others macrophages remained in firm contact with fibroblasts for many hours. Attachment of one macrophage did not prevent attachment of others, since many fibroblasts made firm contact with four or five other cells. Not all macrophages, however, attached themselves to fibroblasts. Macrophages injected with Lucifer yellow did not transfer the dye to fibroblasts with which they had made contact, nor was there any reverse transfer from injected fibroblasts to macrophages. Lucifer yellow was, however, transferred rapidly from injected fibroblasts to other adjacent fibroblasts with which they had formed gap junctions. Macrophages whose lysosomes had been pre-loaded with FITC-dextran did transfer this ligand to recipient fibroblasts, where it became localised in a perinuclear pattern with many bright punctate patches adjacent to donor macrophages. Transfer of FITC-dextran was blocked when cells were separated by nucleopore membranes in an analogous manner to transfer of endogenous lysosomal beta-glucuronidase.
Insights
Mouse macrophages attach to human fibroblasts, transferring lysosomal contents like FITC-dextran but not Lucifer yellow dye. This cell-cell interaction highlights macrophage-fibroblast communication pathways.
Area of Science:
- Cell Biology
- Immunology
- Biochemistry
Background:
- Cell-cell interactions are crucial for tissue function and immune responses.
- Understanding communication between macrophages and fibroblasts is key to inflammatory and repair processes.
Purpose of the Study:
- To investigate the nature of interactions between mouse peritoneal macrophages and human fibroblasts.
- To determine the transfer of cellular contents and identify potential communication mechanisms.
Main Methods:
- Co-culture of mouse peritoneal macrophages with beta-glucuronidase deficient human fibroblasts.
- Utilized fluorescent dyes (Lucifer yellow) and ligands (FITC-dextran) to track intercellular transfer.
- Employing nucleopore membranes to assess contact-dependent transfer.
Main Results:
- Macrophages formed stable attachments with fibroblasts, with multiple macrophages attaching to single fibroblasts.
- No transfer of Lucifer yellow was observed between macrophages and fibroblasts, indicating lack of direct cytoplasmic exchange or gap junctions.
- FITC-dextran, loaded into macrophage lysosomes, was transferred to fibroblasts, suggesting lysosome-mediated communication.
- Transfer of FITC-dextran was contact-dependent and analogous to endogenous lysosomal enzyme transfer.
Conclusions:
- Macrophages and fibroblasts engage in stable, contact-dependent interactions.
- Macrophage lysosomes can transfer contents to fibroblasts, indicating a novel pathway for intercellular communication.
- This transfer mechanism may play a role in modulating fibroblast function during inflammatory or repair processes.