AL-57, a ligand-mimetic antibody to integrin LFA-1, reveals chemokine-induced affinity up-regulation in lymphocytes

Motomu Shimaoka, Minsoo Kim, Edward H. Cohen, Wei Yang, Nathan Astrof, Dan Peer, Azucena Salas, Audrey Ferrand, Timothy A. Springer

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


Affinity of integrin lymphocyte function-associated antigen 1 (LFA-1) is enhanced by conformational changes from the low-affinity closed form to the high-affinity (HA) open form of the ligand-binding inserted (I) domain as shown by work with purified I domains. However, affinity up-regulation of LFA-1 on the cell surface by physiological agonists such as chemokines has yet to be demonstrated by monovalent reagents. We characterize a mAb, AL-57 (activated LFA-1 clone 57), that has been developed by phage display that selectively targets the HA open conformation of the LFA-1 I domain. AL-57 discriminates among low-affinity, intermediate-affinity, and HA states of LFA-1. Furthermore, AL-57 functions as a ligand mimetic that binds only upon activation and requires Mg2+ for binding. Compared with the natural ligand intercellular adhesion molecule-i, AL-57 shows a tighter binding to the open I domain and a 250-fold slower off rate. Monovalent Fab AL-57 demonstrates affinity increases on a subset (≈10%) of lymphocyte cell surface LFA-1 molecules upon stimulation with CXCL-12 (CXC chemokine ligand 12). Affinity up-regulation correlates with global conformational changes of LFA-1 to the extended form. Affinity increase stimulated by CXCL-12 is transient and peaks 2 to 5 min after stimulation.

Original languageEnglish (US)
Pages (from-to)13991-13996
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number38
StatePublished - Sep 19 2006


  • Activation
  • Cell adhesion
  • Conformational changes
  • Phage display

ASJC Scopus subject areas

  • Genetics
  • General


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