1α , 25-dihydroxyvitamin D3Promotes Fusion of Mouse Alveolar Macrophages Both by a Direct Mechanism and by a Spleen Cell-Mediated Indirect Mechanism

• Published in: Proceedings of the National Academy of Sciences - PNAS 1983-09, Vol.80 (18), p.5583-5587
• Main Authors: Abe, Etsuko, Miyaura, Chisato, Tanaka, Hirofumi, Shiina, Yoshiko, Kuribayashi, Takeo, Suda, Satoshi, Nishii, Yasuho, DeLuca, Hector F., Suda, Tatsuo
• Format: Article
• Language: English
• Subjects: Alveolar macrophages; Bones; Cholecalciferols; Cultured cells; Giant cells; Macrophages; Osteoclasts; Spleen; Spleen cells; T lymphocytes
• ISSN: 0027-8424

Extensive fusion was induced in mouse alveolar macrophages by treatment with conditioned media obtained from splecn cell cultures treated with 15 μ g of phytohemagglutinin or concanavalin A per ml or with 12 nM 1α , 25-dihydroxyvitamin D3[1α , 25(OH)2D3]. The fusion rate was 80-90% on day 3. In addition, 1α , 25(OH)2D3added directly to alveolar macrophages induced fusion of about 35% of the cells on day 3, whereas direct addition of phytohemagglutinin and concanavalin A did not enhance fusion at all. When conditioned media from spleen cell or T cell cultures treated with 12 nM 1α , 25(OH)2D3were applied to a Sephadex G-100 column, a fusion factor (Mr37,000-70,000) could be separated from 1α , 25(OH)2D3. 1α , 25(OH)2D3induced fusion at 0.012-120 nM in a dose-dependent manner both by direct action and by spleen cell-mediated indirect action, but the fusion rate was always much greater in the latter than in the former at each concentration of the vitamin. Of the vitamin D3derivatives tested, 1α , 25(OH)2D3was the most potent, followed successively by 1α , 24R, 25-trihydroxyvitamin D3, 1α -hydroxyvitamin D3, 25-hydroxyvitamin D3and 24R,25-dihydroxyvitamin D3. These results clearly indicate that 1α , 25(OH)2D3induces fusion of mouse alveolar macrophages by both a direct and an indirect mechanism, the latter mediated by spleen cells, probably by T cells.