Proteinase inhibitors in the kidney and its tumours

The proteinase inhibitors alpha-1-antitrypsin and alpha-1-antichymotrypsin are found in a variety of tissues including the kidney. We have used the immunoperoxidase technique to study the distribution of these glycoproteins in 10 fetal and five adult kidneys and in 44 renal tumours. Proteinase inhibitors were found in fetal kidneys in the cells of the metanephric blastema, primitive mesenchyme and in proximal tubules. They were found in proximal tubules of adult kidneys. These substances were also found in the mesenchyme of nephroblastomas and in the tumour cells of clear cell, oncocytic and sarcomatoid variants of renal cell carcinoma. These observations are significant in the understanding of the patterns of differentiation of which renal cell carcinoma is capable.