| Unique autologous antibodies (Abs) against platelet integrin GPIIIa49-66 (CAPESIEFPVSEARVLED) have been detected in HIV-1-ITP patients, which induce complement-independent platelet fragmentation through reactive oxygen species (ROS) release. However, the efficiency in induction of platelet fragmentation is inconsistent among the different patient Abs or similar rabbit polyclonal Abs against the region and the reason remains unclear. In this study, we developed a batch of murine monoclonal antibodies (mAbs) against different locus of GPâ…¢a49-66 region by hybridoma technology. All these mAbs are capable of binding to human platelets. Among these mAbs, clones 1E7 and 5A10 were identified to target the epitope of GPâ…¢a49-57 (CAPESIEFP, named P1); clones 1C1 and 1E5 with GPIIIa57-64 (PVSEARVL, named P2), and clones 4D5 and 5F8 with GPIIIa59-66 (SEARVLED, named P3). By incubation of human platelets with these mAbs, the platelet fragmentation induced by mAbs against P1 was 5-6 folds higher than control mAb (6-fold for 5A10 and 5.6-fold for 1E7). However, platelet fragmentation induced by mAbs against P2 or P3 was below 2 folds (1.9-fold by 1C1 and 1.1-fold by 5F8). Thus, our data demonstrate that platelet integrin GPIIIa49-57 (CAPESIEFP) is the pivotal switch controlling platelet fragmentation. |
