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GJ Dover and SH Boyer
We outline a method for estimating either HbF or HbA content in single
erythrocytes and their precursors. Our method depends on microphotometric
assay of darkfield reflectance arising from individual pericellular
immunoprecipitates developed with anti-HbF or anti-HbA. When
uniform-diameter latex microspheres were used to normalize comparisons
between preparations, mean coefficient of variation for HbF reflectance
among separate preparations of the same sample was < 3%. Reflectance is
a faithful (r = 0.99) linear function of the logarithm of picograms per
cell in samples with known HbF or HbA content. The following features
emerged from such analyses. First, despite the use of
antigenically-specific antihemoglobins from different sources, the least
detectable quantity of HbF (3.2 pg) and HbA (14.8 pg) remained invariant.
Second, these detection thresholds depends on antihemoglobin affinity
constants but are little influenced by antibody concentration. Third, our
procedure is equally valid for persons with normal HbF constant (mean +/-
SD = 4.4 +/- 0.3 pg per cell, 15 subjects) and for those with much higher
levels. Fourth, like the percentage of HbF- bearing cells, HbF content is
usually unchanging in serial samples. Fifth, the utility of the method is
evidenced in bone marrow analyses of five hematologically normal persons in
whom HbF content, unlike HbA content, remained constant throughout
maturation from erythroblasts to erythrocytes. In vivo HbF biosynthesis is
thus normally completed long before HbA production.
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| Copyright © 1980 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||