Expression of alpha(4)-integrins on human neutrophils

alpha(4) Integrals are important adhesion molecules mediating binding of ly mphocytes, monocytes, and eosinophils to multiple, cellular and extracellul ar ligands. Mature neutrophils have been recently suggested to express alph a(4)-integrins as web. We studied whether human neutrophils can synthesize alpha(4)-integrins upon activation in vitro or in vivo. Two anti-alpha(4) m Abs, but not multiple subclass-matched non-binding controls, reacted with g ranulocytes in an inducer and time-dependent manner. Nevertheless, staining with Ig subclass-specific second-stage reagents surprisingly revealed that commercial anti-alpha(4) mAbs contain two distinct (Igs) the alpha(4)-spec ific IgG1 and an IgG2a of an unknown specificity. We showed that in vitro i nductions used by us and others only induce the binding of nonspecific IgG2 a from the commercial HP2/1 to activated neutrophils. By reverse-transcript ase polymerase chain reaction, alpha(4) mRNA was not detectable in purified neutrophils. Our results show that alpha(4) integrin protein and mRNA are absent from normal and stimulated human neutrophils.