Red Cell Lead, Whole Blood Lead, and Red Cell Enzymes

Simultaneous assay of blood lead (Pb-B) and red cell lead (Pb-Rbc) in 123 samples from 104 urban and suburban students, ages 10–18, shows the ratio of concentration (Pb-Rbc)/(Pb-B) to increase as the hematocrit decreases. On direct assay in 40 samples, plasma lead (Pb-P) was fixed in a narrow range. In 28 students with Pb-Rbc >40 μg/100 ml, the mean red cell 2,3-diphosphoglycerate (2,3-DPG) was 6.05±0.28 (±S.E.), significantly higher (P<.025) than the 5.25±0.18 of 51 students with Pb-Rbc<40 μg/100 ml, although hemoglobin values were comparable (13.83±0.31 versus 13.55±0.20). Analysis of the individual population groups showed this correlation of Pb-Rbc with 2,3-DPG to be primarily related to the intercorrelation of each parameter with hemoglobin. Rbc membrane Na/K ATPase, as per cent of total membrane ATPase, had a median value of 60% in 48 subjects. Na/K ATPase below 60% was found in 10 (77%) of the 13 students with Pb-Rbc≥40 μg/100 ml, but in only 14 of the 35 with Pb-Rbc<40 μg/100 ml (χ(2)=5.1, df=1, P<0.05). Correlation of significant enzyme changes with Pb-Rbc, but not with Pb-B in the normal urban range of Pb-B<35 μg/100 ml suggests Pb-Rbc, increased in anemia, to be a critical factor in the hematotoxicity of lead.