M. Sohmiya et Y. Kato, Molecular and electrical heterogeneity of circulating human erythropoietinmeasured by sensitive enzyme immunoassay, EUR J CL IN, 30(4), 2000, pp. 344-349
Citations number
26
Categorie Soggetti
General & Internal Medicine","Medical Research General Topics
Background We set up a sensitive sandwich enzyme immunoassay (EIA) of human
erythropoietin (EPO) and further investigated molecular weight and structu
ral heterogeneity, and electrical heterogeneity of the circulating EPO in n
ormal human plasma without any concentrating procedure.
Materials and Methods We set up a sensitive sandwich EIA of EPO using anti-
EPO rabbit Fab'-peroxidase conjugate and anti-EPO IgG coated polystyrene ba
lls. Standard EPO and plasma samples obtained from three normal subjects we
re applied to gel chromatographic analysis. Plasma samples obtained from th
ree normal subjects were subjected to preparative isoelectric focusing with
a column (pH 3.5-10).
Results The minimal detectable quantity was 0.15 mIU mL(-1) using 100 mu L
sample. There was a good parallelism between diluted human plasma samples a
nd the standard EPO in the assay. Rat plasma EPO was cross-reacted in the a
ssay. There was a good correlation between EPO levels determined by the EIA
and those of radioimmunoassay (y = 0.897x + 0.564, r = 0.957). Gel chromat
ographic analysis of standard EPO revealed a single peak. On the other hand
, gel chromatographic analysis of unconcentrated plasma samples obtained fr
om three normal subjects revealed at least four components of immunoreactiv
e EPO. Preparative isoelectrical focusing revealed at least four major comp
onents and some other small peaks in normal human plasma samples.
Conclusion These findings indicate the first evidence for molecular and ele
ctrical heterogeneity of circulating EPO in normal human plasma without any
concentrating procedure.