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Flow cytometric analysis of PKH26-labeled goldfish kidney-derived macrophages
D R Barreda1, N F Neumann, M Belosevic
1Department of Biological Sciences, University of Alberta, Edmonton, Canada.
Abstract:
We recently demonstrated that a goldfish macrophage cell line (GMCL) and primary in vitro-derived kidney macrophage (IVDKM) cultures contain three distinct macrophage subpopulations. Morphological, cytochemical, functional, and flow cytometric characterization of these sub-populations suggested that they may represent cells of the macrophage lineage temporally arrested at distinct differentiation junctures of fish macrophage development (putative early progenitors, monocytes, and macrophages). In this study, we examined the proliferation and differentiation events leading to the generation of mature macrophage-like cells from goldfish kidney hematopoietic tissues. The flow cytometric studies were done after labeling macrophages with PKH26 fluorescent dye and analysis of the data using the MODFIT software. Our results showed that IVDKM cultures proliferated non-synchronously, suggesting the presence of a temporal control mechanism regulating the number of cells entering the paths towards maturation. Such control is most evident during early progenitor proliferation and differentiation events. Our results showed that proliferation may not be a requirement for differentiation of early progenitors to putative monocyte and macrophage subsets. Detailed observation of the mature macrophage-like subpopulation indicated that: 1) they appear to develop from both, the differentiation of monocyte-like cells, and direct differentiation of early progenitors in the absence of a monocyte-like stage; and (2) mature macrophage-like cells appeared to be capable of self-proliferation. Our results suggest the presence of alternate pathways of fish macrophage development other than the classical hematopoietic pathway.
Insights
Goldfish kidney macrophages exhibit distinct subpopulations and non-synchronous proliferation, suggesting a temporal control mechanism in fish macrophage development. Alternate differentiation pathways exist beyond the classical hematopoietic route.
Area of Science:
- Immunology
- Cell Biology
- Fish Biology
Background:
- Goldfish macrophage cell lines (GMCL) and primary in vitro-derived kidney macrophage (IVDKM) cultures contain three distinct macrophage subpopulations.
- These subpopulations may represent cells arrested at different fish macrophage development stages: early progenitors, monocytes, and macrophages.
Purpose of the Study:
- To investigate proliferation and differentiation events in goldfish kidney hematopoietic tissues leading to mature macrophage-like cells.
- To elucidate the regulatory mechanisms controlling macrophage maturation and identify alternate developmental pathways.
Main Methods:
- Flow cytometry using PKH26 fluorescent dye labeling of macrophages.
- Data analysis with MODFIT software.
- Characterization of macrophage subpopulations through morphological, cytochemical, and functional assessments.
Main Results:
- IVDKM cultures demonstrated non-synchronous proliferation, indicating temporal control over cell maturation.
- Proliferation is not essential for early progenitor differentiation into monocyte and macrophage subsets.
- Mature macrophage-like cells arise from monocyte differentiation or direct early progenitor differentiation, and can self-proliferate.
Conclusions:
- A temporal control mechanism regulates goldfish macrophage development, particularly during early progenitor stages.
- Alternate pathways for fish macrophage development, distinct from the classical hematopoietic route, are suggested.
- Mature macrophages possess self-proliferation capabilities, contributing to their population dynamics.