Human red blood cell hemolysate is a potent mitogen for renal tubular epithelial cells

Conditions associated with intravascular hemolysis are often complicated by acute renal failure which is characterized by renal vasoconstriction and t ubular injury. However, the effects of human red blood cell (RBC) hemolysat e on renal tubular epithelial cell function have not been well characterize d. We therefore measured the effect of distilled water-lysed human RBCs on cultured LLC-PK1 cell function. We found that human RBC hemolysate produced a marked effect to promote LLC-PK1 H-3-thymidine uptake that was several-f old higher than that produced by maximal concentrations of several known gr owth factors. Partial purification of human RBC hemolysate by sequential ce ntrifugation and passage over a column that removes low molecular weight su bstances each significantly reduced, but did not totally eliminate, the eff ect of human RBC hemolysate to promote H-3-thymidine uptake. Exposure of LL C-PK1 cells to horse myoglobin also stimulated H-3-thymidine incorporation in LLC-PK1 cells. A reducing agent (ascorbic acid) decreased the effect of horse myoglobin and of human RBC hemolysate to promote LLC-PK1 mitogenesis. Ascorbic acid also decreased the methemoglobin content of human RBC hemoly sate. The effect of human RBC hemolysate to increase LLC-PK1 incorporation of H-3-thymidine could also be significantly decreased by either of two inh ibitors of tyrosine kinase. These results suggest that there are several co mponents of human RBC hemolysate that promote LLC-PK1 H-3-thymidine incorpo ration. One of these components appears to be methemoglobin that exerts its effect via a tyrosine kinase signal transduction pathway.