Disparities in estimates of IgG bound to normal platelets
N Blumberg, D Masel and M Stoler
Estimates of the number of IgG molecules bound to normal platelets have
ranged from several hundred to several tens of thousands. The lower
estimates were generated from direct binding assays and stoichiometric
assumptions. The higher values derive from competitive binding assays, in
which platelet-associated IgG (PAIgG) is calculated from a standard curve
using soluble IgG standards. Using a kinetic-ELISA (enzyme-linked
immunosorbent assay) antiglobulin assay, we measured normal platelet IgG to
be 21,200 +/- 9,400 molecules per platelet when a competitive assay and
soluble IgG standards were used. Direct measurement of bound antiglobulin
by kinetic-ELISA and stoichiometric assumptions yielded a measurement of
259 +/- 117 IgG molecules per platelet. Soluble IgG and PAIgG are not
comparable in their ability to bind anti-IgG. Disparities in estimates of
normal PAIgG are probably due to methodological differences. The estimate
most likely to be correct is several hundred IgG or less per normal
platelet.
Volume 67,
Issue 1,
pp. 200-202,
01/01/1986
Copyright © 1986 by The American Society of Hematology
