Methods and compositions for the preparation and use of autocrine growth factors

A purified and isolated autocrine growth factor which effects growth of kidney epithelial cells and has the following characteristics:

• (a) an apparent molecular weight of between 3,500 and 10,000 daltons as determined by SDS polyacrylamide gel electrophoresis and ultrafiltration;
• (b) resistant to inhibition by:
• (i) 65 mM dithiothreitol (DTT) for at least one hour;
• (ii) freezing for one week;
• or
• (iii) heating at 56.degree. C. for thirty minutes;
• (c) inhibited by:
• (i) heating at 100.degree. C. for fifteen minutes;
• (ii) exposure to 0.1% trifluoroacetic acid for one hour;
• or
• (iii) treatment with 100 .mu.g/ml of trypsin for three hours at 37.degree. C.;
• (d) stable in 1% acetic acid and over a pH range from 3.1 to 9.5;
• and
• (e) obtained from BSC-1 or MDCK cells or from cells which produce the autocrine growth factor having the characteristics of a factor obtained from BSC-1 or MDCK cells.