?2-Macroglobulin production by cultured human fibroblasts

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Abstract
Alpha2-macroglobulin (α2M), 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 α2M as lung fibroblasts. This quantitative difference in α2M production was also demonstrated in fibroblasts of isogenic origin. There was no difference in the amount of α2M produced between adult and fetal fibroblasts of the same tissue type (i.e., of lung or of skin origin). α2M 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 cross-reacting with human inter-α-trypsin inhibitor, were also made by the cultured fibroblasts. Plasma protease inhibitors not detectable in culture supernatants were α1-antitrypsin, α1-antichymotrypsin, and antithrombin III.