Monoclonal antibodies to human platelet glycoprotein IIb beta that initiate
distinct platelet responses
LK Jennings, DR Phillips and WS Walker
Hybridomas secreting monoclonal antibodies (MoAbs) to human platelet
membrane glycoprotein IIb (GPIIb) were prepared by fusing cells of a mouse
myeloma line to spleen cells from a BALB/c mouse immunized with purified
GPIIb. Six of the hybridomas secreted MoAbs that recognized epitopes on the
23,000-dalton, disulfide-linked subunit of GPIIb, GPIIb beta. All six of
these MoAbs agglutinated platelets in the absence of calcium. The
agglutination titers of three of the MoAbs, however, were enhanced between
2 and 6 log2 dilutions when titrated in the presence of mmol/L of calcium.
The enhancement in titer was the result of MoAb- induced platelet
activation followed by platelet aggregation, a reaction that could also be
initiated by the monovalent Fab fragments prepared from one of the MoAbs.
The MoAbs did not significantly agglutinate platelets from patients with
Glanzmann's thrombasthenia, confirming biochemical evidence that there is a
paucity of GPIIb beta in the membranes of these cells. Our results show
that MoAbs to epitopes on GPIIb beta initiate distinct platelet responses;
therefore, they should be useful for studying the ways in which regions of
surface glycoproteins are involved in platelet-platelet interactions. In
addition, these reagents may prove of value in diagnosing and typing
patients with Glanzmann's thrombasthenia.
Volume 65,
Issue 5,
pp. 1112-1119,
05/01/1985
Copyright © 1985 by The American Society of Hematology
