Fig 2. Collaborative enhancement binding of anti-muPECAM-1 [125I]-mAb 390 in live cells.

Binding curves of anti- [125I]-mAb 390 alone (“solo”) or in the presence of unlabeled mAb Mec13.3 to paired epitope (”paired”) in live cells stably expressing recombinant muPECAM-1 (RmP) (A) and mutant form of muPECAM-1 (RmPK89A) (B) determined by RIA-based method. Increasing concentrations of [125I]-mAb treatments solo or with a paired mAb were added to cells and incubated at 4°C for 2h. The results are presented as total binding corrected for nonspecific binding on REN-WT cells. The effect of co-incubation with paired mAb vs solo was not significant. Yet, Kd changed 0.86 ±0.07-fold in RmP and 0.83±0.05 in RmPK89A. The insets show Scatchard analysis of experiments.