Serum propeptides of type I and III procollagens in renal transplant recipients. A comparison of cyclosporine and azathioprine treatment.

Chronic cyclosporine nephrotoxicity is characterized morphologically by cortical interstitial fibrosis. The most important collagens involved in renal fibrosis are collagen types I and III. In order to estimate the synthesis of type III and type I collagens, we analyzed serum levels of the amino-terminal propeptide of type III procollagen (PIIINP) and the carboxy-terminal propeptide of type I procollagen (PICP) in 11 renal transplant recipients receiving cyclosporine (group CY) and a comparable group of 16 renal transplant recipients treated with azathioprine (group AZ). In addition, 27 healthy subjects and 15 patients with chronic renal disease and reduced renal function (group CRD) were examined. The cyclosporine-treated patients had serum PIIINP and PICP similar to the azathioprine-treated patients. Both groups of renal transplant recipients had significantly increased serum PIIINP compared to healthy controls (2p < 0.01) and serum PIIINP levels similar to group CRD in which serum PIIINP was also elevated compared to healthy controls (2p < 0.01). Mean serum PIIINP levels were: group CY 0.81 U/l (n = 11); group AZ 0.98 U/l (n = 16); controls 0.62 U/l (n = 27); and group CRD 1.06 U/l (n = 15). The renal graft recipients--both cyclosporine- and azathioprine-treated patients--had significantly increased PICP serum levels compared to healthy controls, but the patients with chronic renal disease had serum PICP levels which did not differ from that of healthy controls. Mean serum PICP levels were: group CY174 micrograms/l; group AZ151 micrograms/l; controls 106 micrograms/l; and group CRD119 micrograms/l.(ABSTRACT TRUNCATED AT 250 WORDS)