RESUMO
We have previously reported that CD7 expressed on resting human NK cells is a signal-transducing molecule, which upon ligation with mAb induces a rapid increase in cytoplasmic free calcium, secretion of IFN-gamma, and augmented NK activity against K562 targets. We now demonstrate that Ab-mediated clustering of CD7 molecules on NK cells results in enhanced phosphorylation on tyrosine residues of intracellular proteins of 60, 70, 80, 97, and 120 kDa. In the presence of genistein, a specific inhibitor of protein tyrosine kinase, the enhanced level of tyrosine phosphorylation was blocked, indicating that CD7 may induce signaling via activation of tyrosine kinases. Cross-linking of CD7 or CD16 molecules with primary and secondary Abs, as well as stimulation of NK cells with phorbol ester (PMA) or with calcium ionophore A23187 also induced beta 1 integrin-mediated adhesion of these cells to fibronectin (FN)-coated plastic surfaces. In contrast, cross-linking of CD2 expressed on the surface of NK cells had no significant effect on NK cell adhesion to FN. This adhesion was not associated with up-regulation of expression of alpha 4 beta 1 or alpha 5 beta 1 FN receptors on NK cells, but it required an intact cytoskeleton. The CD7-induced adhesion to FN was mediated by alpha 4 beta 1 and alpha 5 beta 1 integrins, as it was partially blocked by FN connective segment-1 peptide (EILDVPST), the alpha 4 beta 1-binding domain, as well as by RGD-containing peptides, the alpha 5 beta 1-binding domain, but not by EILEVPST or RGE control peptides. NK cell binding to FN was also partially inhibited by mAb to alpha 4, alpha 5, and beta 1 integrins. The mechanism by which cross-linking of CD7 or CD16 on NK cells induced adhesion to FN appeared to involve both protein tyrosine kinase and protein kinase C, because this adhesion was blocked in the presence of either genistein or a protein kinase C inhibitor, staurosporin. Our data demonstrate that signals transduced via triggering of either CD7 or CD16 molecules are involved in the regulation of the functional activity of beta 1 integrins on NK cells.
Assuntos
Antígenos CD/fisiologia , Antígenos de Diferenciação de Linfócitos T/fisiologia , Fibronectinas/metabolismo , Integrinas/metabolismo , Células Matadoras Naturais/fisiologia , Proteínas Tirosina Quinases/metabolismo , Receptores de Fibronectina/metabolismo , Receptores Imunológicos/fisiologia , Tirosina/análogos & derivados , Alcaloides/farmacologia , Sequência de Aminoácidos , Antígenos CD7 , Cálcio/fisiologia , Adesão Celular/efeitos dos fármacos , Citocalasina B/farmacologia , Ativação Enzimática , Genisteína , Humanos , Técnicas In Vitro , Isoflavonas/farmacologia , Dados de Sequência Molecular , Peptídeos/química , Peptídeos/farmacologia , Fosfoproteínas/metabolismo , Fosfotirosina , Receptores de IgG/fisiologia , Transdução de Sinais , Estaurosporina , Acetato de Tetradecanoilforbol/farmacologia , Tirosina/metabolismoRESUMO
The CD7 molecule, one of the earliest T-lymphocyte Ag expressed during ontogeny, has recently been demonstrated to facilitate activation of T cells and to preferentially activate TCR-gamma/delta + subset of T cells. The CD7 Ag is also expressed on human NK cells, but its function has not been determined. In this study, expression and function of CD7 Ag on highly enriched NK cells (94 +/- 3% mean +/- SD, n = 12) obtained by negative selection from peripheral blood of normal donors were investigated. The CD7 Ag was found to be expressed at a significantly (p < 0.002) higher level on fresh NK cells than on IL-2-activated, NK cells. CD7 on human NK cells was found to be a signal-transducing molecule with a rapid increase in cytoplasmic free calcium observed on binding of anti-CD7 mAb to the surface of NK cells. Cross-linking of CD7 induced expression of surface activation molecules such as CD25, CD71, HLA-DR, CD69, and CD54. Activation by anti-CD7 mAb cross-linked to plastic or through goat anti-mouse Ig also induced a variety of NK cell functions: it stimulated secretion of IFN-gamma, led to proliferation of NK cells, as measured by [3H]thymidine incorporation, and significantly enhanced cytotoxicity of NK cells against K562 targets (p < 0.03). However, CD7 on NK cells did not seem to transduce a lytic signal, because it neither mediated redirected killing of Fc gamma R+ murine mastocytoma P815 cells nor triggered lysis of a hybridoma expressing the antibody in a membrane-bound form. CD7 molecules appeared to have a regulatory role in adhesion of NK cells to fibronectin, because cross-linking of CD7 on resting NK cells significantly augmented their adhesion to fibronectin-coated plastic surfaces. However, this induced adhesion was not associated with increased expression of beta 1-integrins on NK cells. Thus, CD7-mediated signals appear to augment function of adhesion molecules on NK cells, which may be involved in NK cell activation by providing both anchorage and costimulatory triggering.
Assuntos
Antígenos CD/metabolismo , Antígenos de Diferenciação de Linfócitos T/metabolismo , Células Matadoras Naturais/imunologia , Antígenos CD7 , Cálcio/metabolismo , Adesão Celular , Moléculas de Adesão Celular/metabolismo , Citotoxicidade Imunológica , Fibronectinas/metabolismo , Humanos , Imunidade Celular , Imunofenotipagem , Interferon gama/biossíntese , Interleucina-2/farmacologia , Ativação Linfocitária , Agregação de Receptores , Receptores Imunológicos/metabolismoRESUMO
Natural killer (NK) cells selected by IL-2-induced rapid adherence to plastic and called A-NK cells represent a phenotypically and functionally distinct subset of mature peripheral blood NK cells. To further characterize this subset of NK cells functionally, their potential to express mRNA for the IL-2R and various cytokines after IL-2 activation was examined. Highly purified normal human peripheral blood resting NK (R-NK) cells were obtained by negative immunoselection using OKT3 mAb and magnetic beads coated with goat anti-mouse Ig. By two-color flow cytometry, > 90% of these R-NK cells were either CD3-CD56+CD16+ or - or CD3-CD56-CD16+. R-NK cells were activated in the presence of 6000 IU/ml (22 nM) of IL-2 for different periods of time. After 1, 3, 5, or 24 h, plastic-adherent (A) and nonadherent (NA) NK cells were separated and compared for the expression of the IL-2R or cytokine mRNA by in situ hybridization, using 35[S]-cDNA probes. Only low proportions of R-NK cells expressed genes for IL-2Rp55 (16%) or cytokines IL-2 (20%), IFN-gamma (18%), TNF-alpha (16%), and TGF-beta (7%). Thus, the genes for the IL-2Rp55 and these cytokines were not constitutively expressed by most human R-NK cells, and there was no indication that the NK cells used in these experiments were activated in vivo or during the purification procedure. However, larger proportions of R-NK cells showed expression of mRNA for IL-1-beta (35%) and IL-6 (40%), which indicates that genes for these cytokines may be constitutively expressed in a substantial proportion of normal human circulating NK cells. When R-NK cells were incubated in the presence of 22 nM of IL-2 for 1 to 24 h and separated into A-NK cells and NA-NK cells, a large proportion of A-NK cells became positive for IL-2R and cytokine gene expression. In contrast, the proportion of mRNA-positive NA-NK cells was similar or lower than that observed for R-NK cells, with the exception of an increase in TGF-beta.(ABSTRACT TRUNCATED AT 400 WORDS)
Assuntos
Adesão Celular/efeitos dos fármacos , Citocinas/genética , Interleucina-2/farmacologia , Células Matadoras Naturais/citologia , Células Matadoras Naturais/metabolismo , Receptores de Interleucina-2/genética , Expressão Gênica , Humanos , Hibridização In Situ , Interferon gama/genética , Interleucina-1/genética , Interleucina-2/genética , Interleucina-6/genética , RNA Mensageiro/genética , Transcrição Gênica , Fator de Crescimento Transformador beta/genética , Fator de Necrose Tumoral alfa/genéticaRESUMO
In a nude mouse model of human squamous-cell carcinoma of the head and neck (SCCHN), locoregional therapy with interleukin 2 and human lymphokine-activated killer (LAK) cells resulted in a significant inhibition of growth of 3-day established tumors. The same model was used for therapy of 7-day established tumors with highly enriched populations of human adherent (A)-LAK (CD3- CD56+) cells and IL-2. Peritumoral transfer of 10 x 10(6) A-LAK cells, whose in vitro cytotoxicity against a SCCHN cell line (PCI-I) was not significantly different from that of LAK cells, resulted in complete regression of all 3-day or 7-day human SCCHN in nude mice. An initial inflammatory-type reaction, which appeared within hours of the first peritumoral cell transfer, was accompanied by infiltration initially by granulocytes and plasma cells, and later by mononuclear cells into the tumor stroma. A-LAK cells labelled with a fluorescent dye prior to injection appeared in the tumor stroma within 24 hr and were localized around or in the basal epithelial tumor layer by 48 hr. Histologic sections revealed an increasing epithelial disorganization and progressively decreasing basal epithelial layer, which were proportional to the increasing number of A-LAK cells transferred. Within 4 weeks, the tumors were reduced to amorphous keratinic remnants surrounded by the connective tissue containing abundant mononuclear cells. Local administration of human A-LAK cells and IL-2 to SCCHN tumors growing in nude mice led to accelerated tumor differentiation, keratinization and regression.