British Journal of Industrial Medicine 1982;39:153-156 Mechanism of increased osmotic resistance of red cells in workers exposed to lead

ABSTRACT In order to clarify the mechanism of the increased osmotic resistance of red blood cells in lead workers 19 men employed in a lead refining factory and 18 control male workers employed in railway construction were examined for red cell count, haematocrit, MCV, blood and urine lead concentrations, urine coproporphyrin and 8-aminolevulinic acid, osmotic resistance of red cells, lecithin-cholesterol acyltransferase (LCAT) activity in serum, and cholesterol content and cholesterol-to-phospholipid ratio of the red cell membrane. The results were: (1) The osmotic resistance of the red cells (p < 0 05), cholesterol content of the red cell membrane, blood and urine lead, urine coproporphyrin, and urine 8-ALA concentrations (p < 001) were higher in the lead workers than in the controls. (2) In the lead workers close relationships were observed between the osmotic resis-tance and the blood lead concentration (r =-0-515, p < 005), osmotic resistance and LCAT activity (r = 0O596, p < 0O01), and osmotic resistance and cholesterol of the red cell membrane (r =-0'492, p < 0.05). An increase in the osmotic resistance of red blood cells has been observed in lead workers using a coil planet centrifuge system.'-4 There is a dose-response relationship between the osmotic resistance of red cells and the blood lead concentration. The mechanism of the increased osmotic resistance in lead poisoning has not been completely clarified, however. Recently, Cooper et a15-7 reported an increase in osmotic resistance of red cells in patients with obstructive jaundice and also a close relationship between increased osmotic resistance and an increased cholesterol-to-phospholipid ratio in the red cell membrane. Cooper concluded that membrane cholesterol was the major factor affecting osmotic resistance. The present report describes changes in red cell osmotic resistance and cholesterol in lead workers and clarifies the mechanism of the increased osmotic resistance