alpha 2-Macroglobulin production by cultured human fibroblasts

Alpha 2-macroglobulin (alpha 2M), a high-molecular-weight plasma protease inhibitor has been shown, by both immunological and functional methods, to be produced by cultured adult lung fibroblasts. Cultured skin fibroblasts synthesized approximately one tenth as much alpha 2M as lung fibroblasts. This quantitative difference in alpha 2M production was also demonstrated in fibroblasts of isogenic origin. There was no difference in the amount of alpha 2M produced between adult and fetal fibroblasts of the same tissue type (i.e., of lung or of skin origin). alpha 2M was produced in culture during log-phase growth as well as at confluence. Two other plasma protease inhibitors, C1-esterase inhibitor and a substance immunologically crossreacting with human inter-alpha-trypsin inhibitor, were also made by the cultured fibroblasts. Plasma protease inhibitors not detectable in culture supernatants were alpha 1-antitrypsin, alpha 1-antichymotrypsin, and antithrombin III.