Quantitation of cell membrane glycoproteins in pathological conditions using a lectin-bound enzyme-linked immunosorbent assay (ELISA). Application to human platelets in the Bernard-Soulier syndrome.

Several techniques are available to study cell membrane glycoproteins in pathological conditions but these either lack sensitivity or require radiolabelled material or expensive apparatus. We have, therefore, developed a sandwich-type enzyme-linked immunosorbent assay (ELISA) to study patients with the Bernard-Soulier syndrome (BSS), a hereditary platelet disorder characterized primarily, at the molecular level, by glycoprotein Ib (GpIb) deficiency. We have used the lectin wheat germ agglutinin to capture GpIb in the microtiter wells. Following incubation with monoclonal antibody AN51 which recognizes an epitope on GpIb, the immune complex was detected using the streptavidin-peroxidase-biotin complex. Platelet samples from 24 normal controls gave a mean value of 106% whereas in the six BSS patients the mean value was 14% and in the eight obligatory heterozygotes it was 78%. The technique is simple, inexpensive and sensitive and does not require the use of radioactive material. The assay method could be applied to quantitate other cellular glycoproteins where specific lectins and monoclonal antibodies are available.