Identification and characterization of a human monoclonal antagonistic antibody AL-57 that preferentially binds the high-affinity form of lymphocyte function-associated antigen-1

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

“…Selection of a human Fab library by phage display and identification of AL-57 is described in detail in ref. 32. We studied binding kinetics and selectivity of AL-57 for alternative conformations of the ␣ L I domain by using SPR.…”

“…Details of selection of a human Fab library by phage display are described elsewhere (32). Briefly, the library was positively selected with the disulfide-locked HA K287C͞K294C mutant I domain and negatively selected with the WT low-affinity I domain (31).…”

Selective gene silencing in activated leukocytes by targeting siRNAs to the integrin lymphocyte function-associated antigen-1

“…The LFA-1 ligand-binding domain, the inserted (I) domain, changes from a closed to an open form with a progressive 10,000-fold increase in affinity in the activated state (10). To study affinity up-regulation of LFA-1, we recently developed an engineered antibody, AL-57, that preferentially binds to the active conformation of LFA-1 (13,14). Unlike most LFA-1 antibodies that bind equally to the HA and low-affinity forms (e.g., TS1/22), AL-57 binds to HA LFA-1 on activated lymphocytes but not to low-affinity LFA-1 on unstimulated cells (14).…”

Structural basis of activation-dependent binding of ligand-mimetic antibody AL-57 to integrin LFA-1

“…This is a tendency also shared by the AL-57 antibody. Both a cell-binding assay (13) and surface plasmon resonance (SPR) analysis (11) showed that the monoclonal antibody AL-57 discriminates among wild-type low-affinity LA, mutationallystabilized intermediate-affinity IA, and mutatationallystabilized high-affinity HA states of LFA-1. With SPR, AL-57 showed no binding to LA domain, but binding to IA and HA domains with K D being approximately 4.7 M and 0.023 M, respectively (11).…”

“…This contrasts with the clinically approved mAb to LFA-1, which binds to the closed conformation of I domain and sterically blocks ligand-binding. An mAb like AL-57 may have favorable pharmacokinetics with long half-life in vivo, and have fewer potential side effects (13).…”