The Relationship between Fusion and Proliferation in Mouse Alveolar Macrophages*

Publisher Website
Google Scholar
Abstract
We have reported that protein factors separated from conditioned media of Concanavalin A-stimulated spleen cell cultures induce growth and fusion of mouse alveolar macrophages. A macrophage growth factor (MGF) was purified and, at the final step of purification on HPLC, eluted at the same position as a colony-stimulating factor (CSF), suggesting that MGF is identical with CSF. In the present study, we examined the relationship between proliferation and fusion of macrophages using purified CSF (MGF) and 1.alpha.,25-dihydroxyvitamin D3 [1.alpha.,25-(OH)2D3]. The latter was used in place of a macrophage fusion factor which is supposed to be contained in the conditioned medium, since macrophage fusion factor has not yet been isolated. Adding less than 5% unfractionated conditioned medium from Concanavalin A-stimulated spleen cells markedly induced proliferation of alveolar macrophages without inducing fusion. In contrast, adding the same unfractionated conditioned medium at concentrations of 10% or more suppressed proliferation dose dependently, whereas it induced fusion reciprocally. Proliferation of macrophages was similarly enhanced by adding purified CSF or retinoic acid. Fusion of macrophages was induced by 1.alpha.,25-(OH)2D3, but not by purified CSF or retinoic acid. Adding 1.alpha.,25-(OH)2D3 together with purified CSF or retinoic acid completely suppressed the increase of proliferation induced by either growth factor, whereas that treatment rather potentiated the fusion induced by 1.alpha.,25-(OH)2D3 alone. These results indicate that the fusion and proliferation of macrophages occur in a reciprocal fashion.

This publication has 13 references indexed in Scilit: