The life span of the human red blood cell.

Many different methods have been used to estimate the average life time of the human red blood cell. The different attempts have yielded estimates which range from 5 to 200 days. Estimates have been made by inducing polycythemia and noting the time required for the return to the normal red cell count; this yielded values of 18 to 30 days (1). Determinations of the amount of iron or pigment excreted have yielded estimates of 20 to 200 days (2). Determinations of the survival time of transfused erythrocytes bymeans of differential agglutination (3, 4) yielded estimates ranging from 30 to 100 days. The use of agglutinogens M and N for tagging erythrocytes gave values of 80 to 120 days (5-7). More recently Callender, Powell, and Witts (8) using Ashby’s differential agglutination method (3) in Rh-positive men (9) concluded from a mathematical analysis of their data that red blood cells live for approximately 120 days. Measurement of the time required for the disappearance of sulfhemoglobin from the blood of cyanosed workers (10) indicated the life span of the red blood cell to be 115 days. Hawkins and Whipple (11) by another technique obtained a value of 124 days for the dog erythrocyte. Glycine has been shown to be a nitrogenous precursor of the protoporphyrin of hemoglobin in the rat (12). The feeding of glycine labeled with N15 to a man also results in the formation of heme containing a comparatively high concentration of N15 (13). After cessation of the feeding of the labeled glycine, the isotope concentration of the heme was followed over a long period of time by analysis of the hemin isolated at intervals. The values rose rapidly to a high level, remained practically constant for many weeks, and then fell quite sharply to a very low level. This finding indicates that the heme is neither involved in the dynamic metabolic state nor reutilized for hemoglobin formation. On these grounds, the curve of N15 concentration of the heme versus time can form the basis for a determination of the average life span of the human red blood cell. This was found to be about 127 days.