I. Cordiano et al., BIOTIN-AVIDIN IMMOBILIZATION OF PLATELET GLYCOPROTEINS (BAIPG) - A NEW CAPTURE ASSAY FOR THE DETECTION OF ANTIPLATETLET ANTIBODIES, Journal of immunological methods, 178(1), 1995, pp. 121-130
Several 'capture' assays are currently employed to identify specific p
latelet antibodies, but all require the use of murine monoclonal antib
odies (MoAbs) against the antigen of interest. We have developed a new
antigen capture assay for the detection of platelet reactive antibodi
es, based on platelet surface sialoglycoprotein labelling with biotin
hydrazide, and a following immobilization of the biotinylated platelet
proteins to microtiter wells that had been coated with streptavidin.
The resulting solid phase can then be used in a simple ELISA to detect
serum and platelet associated antibodies. We describe here two versio
ns of this biotin-avidin immobilization of platelet glycoproteins (BAI
PG) assay. In BAIPG assay type I, the test sera are directly incubated
in microtiter wells previously coated with streptavidin plus biotinyl
ated platelet proteins. The BAIPG type II procedure involves the incub
ation of sera with biotinylated platelets before platelet solubilizati
on, and, after platelet lysis, the immobilization of the immune comple
xes to streptavidin-coated wells. In both cases, the bound antibodies
are determined by alkaline phosphatase conjugated anti-human IgG. Usin
g BAIPG type I, positive results were obtained in 7/33 patients with i
diopathic thrombocytopenic purpura (ITP), 1/10 patients with secondary
immune thrombocytopenia (SIT) and 4/17 with non-immune thrombocytopen
ia (NIT). The BAIPG type II test was positive in 13 out of 33 patients
with ITP, in six out of ten patients with SIT, and in three out of th
e 17 patients with NIT. A comparison between BAIPG and monoclonal anti
body immobilization of platelet antigens (MAIPA) assays showed a high
degree of correlation between the two methods. These results suggest t
hat the BAIPG assay is a valuable new tool for the detection of anti-p
latelet antibodies.