Synthesis of alpha 1-anti-trypsin by human monocytes.

The present report concerns the site of synthesis of alpha 1-anti-trypsin (alpha 1 AT). In this study circulating cells and tissue fragments were incubated with radioactive amino acids to be incorporated during protein synthesis. The de novo synthesis of proteins was demonstrated by autoradiography of the immunoelectrophoretic slide. The results constitute proof that alpha 1 AT is formed by circulating human monocytes and support those obtained in earlier immunofluorescent studies which showed that alpha 1 AT is present in pulmonary macrophages, as could be expected because these cells derive from circulating monocytes. The culture fluid of liver tissues also showed labelled alpha 1 AT, but it is not clear whether in this organ alpha 1 AT is formed by Kupffer cells and/or parenchymal cells.