Blood, 1960, Vol. 16, No. 3, pp. 1285-1297.
© 1960 American Society of Hematology, Inc.
Microspectrophotometric Determination of Nonheme Iron
in Maturing Erythroblasts and its Relationship to
the Endocellular Hemoglobin Formation
C. A. SONDHAUS 1 and
BO THORELL 1
1 Department of Pathology, Karolinska Institute, Stockholm, Sweden.
The strong near-UV absorption of inorganic iron makes possible the microspectrophotometric determination of nonheme intracellular iron as distinct
from hemoglobin-bound iron. Erythroid cells of Salamandra Maculosa were
therefore studied microspectrophotometrically in the near ultraviolet and visible region. Absorption curves from cytoplasmic areas in living and dried
cells were obtained from 310 to 700 mµ., and two component analyses were
made to determine the presence and amount of hemoglobin and nonhemoglobin absorption. Under the experimental conditions, intracellular hemoglobin was present largely as the carbon monoxide derivative, a stable form
which provided a well defined standard to correct for nonspecific absorption
and other spectral distortion due to the optical properties of single cells.
Absorption curves from the youngest cells measured were found to differ
from those of mature cells, the difference curve agreeing most closely with
that of inorganic iron or ferritin in solution. In the youngest cells, nonheme
iron appeared to exceed 6 per cent by weight of hemoglobin, or over 20 times
molar hemoglobin concentration, dropping and remaining at about twice
the hemoglobin molarity from the time hemoglobin synthesis was one-third
complete until maturity. Allowing for the increase of total cell mass with
growth, the data suggest that although young erythroblasts may already
have enough Fe for subsequent Hb synthesis, they continue to incorporate
excess Fe throughout maturation and may thus contain a reserve pool of nonheme iron.
Submitted on January 16, 1960
Accepted on March 15, 1960
