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In vitro fusion of newt macrophages
B Płytycz1, S W Potter, N Cohen
1Department of Zoology, Oregon State University, Corvallis 97331.
Abstract:
Spontaneous formation of multinucleate giant cells is often observed in in vitro cultures of peritoneal adherent macrophages from the newts, Notophthalmus viridescens and Taricha granulosa (urodele amphibians). The frequency of such giant cells in these cultures is increased by the addition of phorbol myristic acetate at the initiation of the cultures. This high frequency of multinucleate cells permitted us to evaluate whether multinucleate giant cells arise by cell fusion and/or by repeated nuclear division without cytokinesis. Cell fusion is readily detectable by scanning electron microscopy. To determine whether nuclear division without cytokinesis also occurs, some cultures were treated with colchicine to arrest mitotic figures; others were pulsed with tritiated thymidine to detect DNA synthesis. Mitotic figures were not seen in acridine orange-stained samples. In monolayers that were processed for autoradiography, only a few nuclei were marked with tritium. These observations suggest that nuclear division does not contribute significantly, if at all, to the formation of multinucleate giant cells from cultured newt peritoneal macrophages.
Insights
Multinucleate giant cells in newt macrophages primarily form through cell fusion, not nuclear division. This study investigated giant cell formation in amphibian macrophages, finding limited evidence for amitosis.
Area of Science:
- Cell Biology
- Amphibian Immunology
- Macrophage Biology
Background:
- Spontaneous formation of multinucleate giant cells is a common observation in in vitro cultures of newt peritoneal macrophages.
- Phorbol myristic acetate treatment increases the frequency of these multinucleate giant cells in cultures.
Purpose of the Study:
- To elucidate the mechanism of multinucleate giant cell formation in urodele amphibian macrophages.
- To determine if giant cell formation occurs via cell fusion or nuclear division without cytokinesis (amitosis).
Main Methods:
- Cultures of peritoneal macrophages from Notophthalmus viridescens and Taricha granulosa were established.
- Scanning electron microscopy was used to detect cell fusion.
- Colchicine treatment and tritiated thymidine pulsing with autoradiography were employed to assess nuclear division and DNA synthesis.
Main Results:
- Scanning electron microscopy confirmed cell fusion as a detectable event.
- Colchicine treatment did not reveal significant mitotic figures.
- Autoradiography showed minimal DNA synthesis in nuclei, indicating limited nuclear division.
Conclusions:
- The formation of multinucleate giant cells in cultured newt peritoneal macrophages predominantly occurs through cell fusion.
- Nuclear division without cytokinesis appears to contribute insignificantly, if at all, to multinucleate giant cell formation in this model.