Background: Elastic fibers are a major fibrillar component of the extracellular matrix of several organs, and their presence provides elastic properties to these tissues. Recent molecular biological studies also have revealed that accumulation of elastotic material in the skin reflects enhanced synthesis of not only elastin but also a fibrillin, an integral component of the elastic fibers, and steady-state levels of the elastin mRNA increased in photodamaged skin. Futhermore, a variety of cytokines, growth factors, and hormones have been shown to modulate elastin gene expression including transforming growth factor- B, tumor necrosis factor-a, insulin-like growth factor-I, glucoreorticoids, cyclic AMP, and vitamin D3. Recently, interleukin-1 B (IL-1 B ) and IL-10 has been shown to up-regulatory function in elastin gene expression. Objective: The purpose of this study was to examine the effect of IL-1 B and IL-10 on elastin gene expression in cultured human fibroblasts. Methods: Fibroblasts cultures were produced with DMEM medium. Cells were treated with IL-1 p (1U/ml, 10U/ml) and IL-10(0.1ng/ml, 1ng/ml, 10ng/ml) nuclear proteins were extracted. Effect of IL-1 B and IL-10 on elastin gene expression were measured by Northern blot analysis, chloram- phenicol acetyltransferase(CAT) assay, and laser confocal microscopy. Results: In Northern blot analysis, IL-1 B and IL-10 showed an up-regulatory effect on elastin mRNA steady-state levels compared with controls incubated without IL-1 p and IL-10. In CAT assay, the percentage of acetylation were increased in cultured fibroblasts. The promoter activities were increased 1.5 and 2.2-fold in IL-1 B (1U/ml, 10U/ml) and 2.2-fold in IL-10(lng/ml, 10ng/ml) treated fibroblasts compared to control groups. In laser confocal microscopy, the results indicated significant increase in the elastin epitopes associated with the cells in cultured with IL-1 B and IL-10. Conclusion: These results show that IL-1 p and IL-10 increase elastin gene expression on transcriptional and protein levels of cultured fibroblasts. It suggests that they may effect on elastin synthesis by a stage up-regulater in human skin. (Korean J Dermatol 1999: 37(7): 846-853)