Figure 7.

Constitutive LFA-1 activity in J19 cells is specific and mediated by the αL subunit cytoplasmic domain. (A–D) Adhesion to ICAM-1 (A and B) and expression of the mAb 24 epitope (C and D) in Jurkat or J19 cells transfected with αM (A and C) or the chimeric α subunit cytoplasmic domain exchange αME (B and D). (A and B) Cells were subjected to adhesion assays on the Mac-1 ligand fibrinogen at 37°C with or without stimulation with PMA (100 ng/ml) for 30 min. Data are mean ± SD of six independent experiments performed in triplicate. (C and D) Jurkat or J19 cells transfected with αM (C) or the chimeric αME (D) were reacted with CD11α activation epitope reporter mAb 24 (solid line, Jurkat; bold line, J19) or with an isotype control mAb (dotted line, Jurkat; stippled line, J19) in the presence of 1 mM Ca²⁺ and 1 mM Mg²⁺ and analyzed by flow cytometry. Shown is a representative experiment.