cIBR effectively targets nanoparticles to LFA-1 on acute lymphoblastic T cells.

Leukocyte function associated antigen-1 (LFA-1) is a primary cell adhesion molecule of leukocytes required for mediating cellular transmigration into sites of inflammation via the vascular endothelium. A cyclic peptide, cIBR, possesses high affinity for LFA-1, and conjugation to the surface of poly(DL-lactic-co-glycolic acid) nanoparticles can specifically target and deliver the encapsulated agents to T cells expressing LFA-1. The kinetics of targeted nanoparticle uptake by acute lymphoblastic leukemia T cells was investigated by flow cytometry and microscopy and compared to untargeted nanoparticles. The specificity of targeted nanoparticles binding to the LFA-1 integrin was demonstrated by competitive inhibition using free cIBR peptide or using the I domain of LFA-1 to inhibit the binding of targeted nanoparticles. The uptake of targeted nanoparticles was concentration and energy dependent. The cIBR-conjugated nanoparticles did not appear to localize with lysosomes whereas untargeted nanoparticles were detected in lysosomes in 6 h and steadily accumulated in lysosomes for 24 h. Finally, T-cell adhesion to epithelial cells was inhibited by cIBR nanoparticles. Thus, nanoparticles displaying the cIBR ligand may offer a useful targeted drug delivery system as an alternative treatment of inflammatory diseases involving transmigration of leukocytes.