GROWTH-HORMONE STIMULATES MULTINUCLEATED CELL-FORMATION IN LONG-TERM BONE-MARROW CULTURES

Although the effects of growth hormone on bone metabolism are well-doc umented, their role in the regulation of immune responses such as the inflammatory process has not been thoroughly explored. This study inve stigated the formation of multinucleated cells (MNC) in long-term huma n hone marrow cultures. Experiments using 1 and 100 ng/ml of human rec ombinant growth hormone (hGH) and 10(-7) M of 1,25 dihydroxyvitamin D3 (VD3) showed that hGH increased the total number and nucleation of MN C. The effects of hGH were generally greater than those observed with VD3. Cytological and immunological characterization of MNC revealed se veral macrophage polykaryon features. MNC did not respond to calcitoni n in a cyclic adenosine monophosphate assay and failed to resorb denti n slices. These results demonstrate that MNC formed in the presence of hGH and VD3 present an essentially macrophage polykaryon phenotype. I n this contest, growth hormone may be involved in the inflammatory pro cess through upmodulation of macrophage polykaryon formation.