Human NK cells express on cell surface an integrine structure which mediate their adehesion to fibronectin

Adhesion molecules are involved in the cellular interactions necessary for the development of the immune response. A family of cell adhesion receptors, termed integrins, functionally implicated in these biological events has been recently described. This superfamily includes several cell surface heterodimers, composed of noncovalently linked ot and B chains, which are involved in both cell attachment to extracellular matrix proteins and in cell-cell interactions. The integrin superfamily is presently divided into three groups based on the sharing of a common B chain, that are B1, B2 and B3. A large body of evidence has demonstrated that one family of integrins, the leukocyte adhesion proteins, composed of LFA-1 (CDl1a), Mac-1 (CD1 lb) and pl50,95 (CD1 lc), whose common B chain is named B2 (CD18), is expressed both on T cells and”NK cells controlling their cytotoxic functions. More recently a similar role for laminin and fibronectin, two extracellular matrix glycoproteins, has been described in NK cell cytotoxicity. I In this study we present evidence that human NK cells express some molecules of another integrin family, VLA (very late activation antigens). They are expressed on resting and activated lymphocytes, on monocytes, macrophages and certain nonlymphoid cells. Several members of this family mediate cell interaction with extracellular matrix molecules such as fibronectin, laminin and collagen and play a major role during cell migration, spreading and differentiation. Many of these receptors have been shown to bind their ligands at sites that include the tripeptide arg-gly-asp (RGD), a sequence which is common to many extracellular proteins. Our results indicate that human NK cells express the B1 chain of VLA, the u chain of VLA4 and react with a goat anti-human fibronectin receptor (FNr) antiserum arisen against the affinity purified human placenta FNr. Moreover, we show that NK cells adhere to human plasma fibronectin-coated plates and that this adhesion is blocked by the antibody against FNr and a RGD-containing peptide.