An ESR spin label study of childhood kidney tumours.

The isolated membranes of cells from normal kidneys, foetal kidneys, Wilms' tumours, and bone-metastasizing renal tumours of childhood (BMRTC) have been examined by electron spin resonance, using the lipophilic spin label 5-doxyl stearic acid. No differences in membrane rigidity were detected between normal kidney cells and Wilms' tumour cells, over the temperature range 5 to 40 degrees C. The membranes of foetal kidney cells showed no significant difference at physiological temperatures, but were more rigid than the membranes of normal kidney cells at lower temperatures. In contrast, BMRTC cells showed lower membrane rigidity than normal kidney cells at all temperatures studied, BMRTC cells, unlike normal kidney and Wilms' tumour cells, lack surface fibronectin, but addition of fibronectin to BMRTC cell membranes, in suspension, had no detectable effect on their rigidity.