Probing Single Icam-1/Lfa-1 Interaction under External Force

RESULTS. The LFA-1/ICAM-1 bond was stretched by the cantilever until it finally ruptured, resulting in a sharp transition in the force-displacement curve. The measured unbinding force of the complex was derived from the magnitude of this transition. The unbinding of the LFA1/ICAM-1 complex by the application of external forces was examined in the context of the Bell model[4]. In this model, an applied force distorts the energy landscape of the LFA-1/ICAM-1 complex resulting in a lowering of the activation barrier(s). The AFM force measurements revealed two activation barriers in the dissociation of the LFA-1/ICAM-1 complex. The outer energy barrier was obtained at the slow loading regime of 10 to 10,000 pN/s. The for the dissociation of the low affinity LFA-1/ICAM-1 complex in this loading regime was 2 s , whereas the -1