Whole Platelet-Captured Enzyme Linked Immunosorbent Assay (WPC-ELISA) for Glycoprotein Ib

We describe here a simple enzyme-linked immunosorbent assay (ELISA) for the quantiation of GPIb of freshly-prepared washed platelets. This assay used rabbit antihuman platelet antibody as a platelet-capturing antibody and an anti-GPIb monoclonal antibody (OP-F1) conjugated with horseraddish peroxidase as a second antibody. The lowest concentration of GPIb antigen measurable by this ELISA was 0.01% of normal platelets when determined using a platelet concentration of 105/μl. The average value (mean±2SD) of platelet GPIb antigen from 30 normal individuals was 93.1±20.3%. Two unrelative patients with Bernard-Soulier syndrome showed less than 0.1% and 4.5%, respectively of normal platelet GPIb. In 30 patients with chronic renal failure (CRF), the GPIb antigen levels (43.1±19.9%) were also significantly reduced (p