Renotropic growth factor found in cancer patient sera after removal of cancer-bearing kidney.

We have used two sets of primary human kidney culture systems for assaying human renotropic growth factor in day 5 postnephrectomized human sera. The first set of primary kidney cell cultures was prepared from one hydronephrotic kidney and used for assaying the renotropic growth stimulating activity of six kidney cancer patients sera simultaneously. The level of renotropic growth-stimulating activity varies from patient to patient. The postnephrectomized sera of three patients showed rather small (27 to 68%) increase over their prenephrectomized sera. The postnephrectomized sera of the remaining three patients showed a much greater (2.69- to 3.19-fold) increase over their prenephrectomized sera. Variation in the growth-stimulating activities produced in these uninephrectomized kidney cancer patients is most probably due to different levels of renal function loss by removal of the cancer-bearing kidney. Each cancer-bearing kidney has a different proportion of healthy kidney region to diseased (nonfunctional) region. The second set of primary kidney cell cultures was prepared from a healthy noncancerous region of a cancer-bearing kidney and used to assay for renotropic growth-stimulating activities in two different unilaterally nephrectomized kidney transplantation donor sera. Increased levels of growth-stimulating activity are quite similar and high (4.19- to 4.79-fold increase above their prenephrectomized sera). These high and similar assay values of the renotropic growth factor produced in two healthy humans suggest the sensitivity and reliability of the assay method with the use of the noncancerous cells from the cancer-bearing kidney.