Intracellular calcium and calcineurin regulate neutrophil motility on vitronectin through a receptor identified by antibodies to integrins alpha v and beta 3

Buffering of intracellular calcium ([Ca2+](i)) or inhibition of the calcium/calmodulin-dependent phosphatase, calcineurin, results in neutrophils being unable to detach from vitronectin with a consequent loss of motility, Treatment of [Ca2+](i)-buffered or calcineurin-inhibited neutrophils with monoclonal antibodies (MoAbs) to beta 3 or alpha v beta 3 integrins allowed neutrophils to detach and restored motility. Quantitative immunofluorescence and flow cytometry showed that MoAbs specific for beta 3, alpha v, or alpha v beta 3 integrins bind to neutrophils. Immunolocalization studies using antibodies to the highly conserved cytoplasmic domains of alpha v and beta 3 also identified the receptor on neutrophils. Whereas antibodies to cuv, alpha v beta 3, and beta 3 recognized the receptor in intact cells, only the beta 3 MoAb immunoprecipitated the receptor from a neutrophil cell lysate. The cu subunit co-immunoprecipitated by the beta 3 antibody reacted with an antibody to alpha v by Western blot, Peptide maps of V8 protease digests showed a strong similarity in alpha and beta chains precipitated by antibodies to beta 3 from neutrophils and endothelial cells. These results indicate that [Ca2+](i) and calcineurin regulate neutrophil motility on vitronectin through an alpha v beta 3-like receptor. Although we cannot rule out the possibility that neutrophils have an isoform of alpha v, such an isoform would have to be similar enough to react with alpha v- and alpha v beta 3-specific MoAbs in intact cells. (C) 1996 by The American Society of Hematology.