ROLE OF THE KIDNEY IN THE EXPRESSION OF LOW-MOLECULAR-WEIGHT FACTORS WITH GROWTH-FACTOR ACTIVITY

Small molecules of peptidic nature, called low molecular weight growth factors (LMW-GF <1000 Da) are present in normal human serum ultrafilt rate. They enhance the somatomedin activity as measured by the incorpo ration of (SO4)-S-35 into chick embryo cartilages. On the basis of thi s in vitro test, LMW-GF activities were measured in serum ultrafiltrat es of hemodialyzed patients and renal transplant recipients during the post-transplantation follow-up. LMW-GF activity was always zero in pa tients with chronic renal failure. It was checked that these results w ere not due to the presence of low molecular weight somatomedin inhibi tors or to the increased sulfate concentration. After successful renal transplantation, the LMW-GF activity of patients ultrafiltrates retur ned to normal at the same time or before the improvement of renal func tion. In case of post-transplant complications, a decrease in LMW-GF a ctivity accompanied or even occurred prior to impairment of renal func tion. In functioning graft, LMW-GF activity reappears rapidly, whereas its normalization is delayed in case of tubular nephropathy or episod e of acute rejection. It was suggested that the kidney is involved in LMW-GF molecules production or processing. It could be speculated that LMW-GF activity might be a prognostic factor in renal transplantation .