Localization of a PlA1 epitope to the amino terminal 66 residues of
platelet glycoprotein IIIa
RD Bowditch, PH Tani, CE Halloran, AL Frelinger , R McMillan and MH Ginsberg
Committee on Vascular Biology, Scripps Research Institute, La Jolla, CA
92037.
A platelet glycoprotein (GP) IIIa epitope library was constructed by
insertion of randomly cleaved GPIIIa cDNA fragments in the prokaryotic
expression vector lambda gt22 and screened with purified anti-PlA1
antibodies for clones expressing a PlA1 epitope. Five independent clones
were isolated and characterized by nucleotide sequencing. The smallest
anti-PlA1 reactive clone obtained encoded the amino terminal 66 residues of
mature GPIIIa. Substitution of leucine33 (PlA1) with a proline33 (PlA2) by
in vitro mutagenesis resulted in the loss of anti- PlA1 reactivity;
however, this clone still reacted with anti-GPIIIa polyclonal antibodies.
These data indicate that a PlA1 alloantigenic epitope is located within a
small, unglycosylated fragment of GPIIIa containing the polymorphism
responsible for the PIA phenotype. Furthermore, these results prove that
small recombinant mimics of a PlA1 epitope may be synthesized and used for
detection of these alloantibodies.
Volume 79,
Issue 3,
pp. 559-562,
02/01/1992
Copyright © 1992 by The American Society of Hematology
