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p46, a novel natural killer cell-specific surface molecule that mediates cell activation.

Sivori S, Vitale M, Morelli L, Sanseverino L, Augugliaro R, Bottino C, Moretta L, Moretta A - J. Exp. Med. (1997)

Bottom Line: Upon mAb-mediated cross-linking, p46 molecules induced strong cell triggering leading to [Ca2+]i increases, lymphokine production, and cytolytic activity both in resting NK cells and NK cell clones.The p46-mediated induction of Ca2+ increases or triggering of cytolytic activity was downregulated by the simultaneous engagement of inhibitory receptors including p58, p70, and CD94/NKG2A.Both the unique cellular distribution and functional capability of p46 molecules suggest a possible role in the mechanisms of non-major histocompatibility complex-restricted cytolysis mediated by human NK cells.

View Article: PubMed Central - PubMed

Affiliation: Istituto di Istologia ed Embriologia Generale, Università di Genova, Genova, Italy.

ABSTRACT
Limited information is available on the surface molecules that are involved in natural killer (NK) cell triggering. In this study, we selected the BAB281 monoclonal antibody (mAb) on the basis of its ability to trigger NK-mediated target cell lysis. BAB281 identified a novel NK cell-specific surface molecule of 46 kD (p46) that is expressed by all resting or activated NK cells. Importantly, unlike the NK cell antigens identified so far, the expression of p46 was strictly confined to NK cells. Upon mAb-mediated cross-linking, p46 molecules induced strong cell triggering leading to [Ca2+]i increases, lymphokine production, and cytolytic activity both in resting NK cells and NK cell clones. The p46-mediated induction of Ca2+ increases or triggering of cytolytic activity was downregulated by the simultaneous engagement of inhibitory receptors including p58, p70, and CD94/NKG2A. Both the unique cellular distribution and functional capability of p46 molecules suggest a possible role in the mechanisms of non-major histocompatibility complex-restricted cytolysis mediated by human NK cells.

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All human NK cell clones can be triggered via p46 molecule.  (a) 10 NK cell clones (representative of >100 clones analyzed) were assessed for cytolytic activity against the FcγR+ P815 target cells in the absence (□) or presence of anti-p46 mAb (▪), anti-CD16 mAb (▨ ), or  anti-CD56 mAb (▥ ). Two clones (B1 and B2) representative of the infrequent CD56+16− NK cell clones, were triggered only by anti-p46  mAb. (b and c) Three representative NK cell clones were analyzed for  IFN-γ or TNF-α production in the absence (□) or presence of anti-p46  mAb (▪) or anti-CD56 mAb (▥ ).
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Figure 4: All human NK cell clones can be triggered via p46 molecule. (a) 10 NK cell clones (representative of >100 clones analyzed) were assessed for cytolytic activity against the FcγR+ P815 target cells in the absence (□) or presence of anti-p46 mAb (▪), anti-CD16 mAb (▨ ), or anti-CD56 mAb (▥ ). Two clones (B1 and B2) representative of the infrequent CD56+16− NK cell clones, were triggered only by anti-p46 mAb. (b and c) Three representative NK cell clones were analyzed for IFN-γ or TNF-α production in the absence (□) or presence of anti-p46 mAb (▪) or anti-CD56 mAb (▥ ).

Mentions: A panel of >100 NK cell clones were assessed for cytolytic activity in the presence of BAB281 or anti-CD16 (c127) mAbs in a redirected killing assay against the FcγR+ P815 target cells. Some of these clones were also analyzed for lymphokine production in the presence of plastic adherent BAB281 mAb. The cytolytic activity of 10 representative NK cell clones is shown in Fig. 4 a. It can be seen that most NK cell clones displayed strong cytolytic responses to both anti-p46 and anti-CD16 mAbs, whereas no increments of cytolytic activity were observed in the presence of the isotype-matched (anti-CD56, IgG1) c218 mAb. Anti-p46 mAb also triggered two clones (B1 and B2), which did not respond to anti-CD16 mAb. These two clones are representative of the rare peripheral blood NK cells displaying the CD3−56+16− phenotype. Some differences in the staining intensity with anti-p46 mAb was observed among different NK cell clones (not shown). Interestingly, this appears to correlate, at least partly, with the degree of anti-p46–induced cytolytic activity as well as with the spontaneous cytolytic activity of the different NK cell clones. Although not shown, the p46-mediated NK cell triggering was not induced by the (Fab′)2 fragment of anti-p46 mAb. These data indicate that cross-linking of p46 molecules is required in order to induce triggering of NK cell-mediated cytolytic activity. Indeed, lysis of FcγR− target cells was not incremented by anti-p46 mAbs. On the other hand, a partial inhibition mediated by anti-p46 mAb could be detected against some FcγR− target cells (including C1R and IGROV cell lines). At present it is not clear whether this inhibition reflects the interference with the interaction between p46 and its putative ligand expressed by these target cells.


p46, a novel natural killer cell-specific surface molecule that mediates cell activation.

Sivori S, Vitale M, Morelli L, Sanseverino L, Augugliaro R, Bottino C, Moretta L, Moretta A - J. Exp. Med. (1997)

All human NK cell clones can be triggered via p46 molecule.  (a) 10 NK cell clones (representative of >100 clones analyzed) were assessed for cytolytic activity against the FcγR+ P815 target cells in the absence (□) or presence of anti-p46 mAb (▪), anti-CD16 mAb (▨ ), or  anti-CD56 mAb (▥ ). Two clones (B1 and B2) representative of the infrequent CD56+16− NK cell clones, were triggered only by anti-p46  mAb. (b and c) Three representative NK cell clones were analyzed for  IFN-γ or TNF-α production in the absence (□) or presence of anti-p46  mAb (▪) or anti-CD56 mAb (▥ ).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2211712&req=5

Figure 4: All human NK cell clones can be triggered via p46 molecule. (a) 10 NK cell clones (representative of >100 clones analyzed) were assessed for cytolytic activity against the FcγR+ P815 target cells in the absence (□) or presence of anti-p46 mAb (▪), anti-CD16 mAb (▨ ), or anti-CD56 mAb (▥ ). Two clones (B1 and B2) representative of the infrequent CD56+16− NK cell clones, were triggered only by anti-p46 mAb. (b and c) Three representative NK cell clones were analyzed for IFN-γ or TNF-α production in the absence (□) or presence of anti-p46 mAb (▪) or anti-CD56 mAb (▥ ).
Mentions: A panel of >100 NK cell clones were assessed for cytolytic activity in the presence of BAB281 or anti-CD16 (c127) mAbs in a redirected killing assay against the FcγR+ P815 target cells. Some of these clones were also analyzed for lymphokine production in the presence of plastic adherent BAB281 mAb. The cytolytic activity of 10 representative NK cell clones is shown in Fig. 4 a. It can be seen that most NK cell clones displayed strong cytolytic responses to both anti-p46 and anti-CD16 mAbs, whereas no increments of cytolytic activity were observed in the presence of the isotype-matched (anti-CD56, IgG1) c218 mAb. Anti-p46 mAb also triggered two clones (B1 and B2), which did not respond to anti-CD16 mAb. These two clones are representative of the rare peripheral blood NK cells displaying the CD3−56+16− phenotype. Some differences in the staining intensity with anti-p46 mAb was observed among different NK cell clones (not shown). Interestingly, this appears to correlate, at least partly, with the degree of anti-p46–induced cytolytic activity as well as with the spontaneous cytolytic activity of the different NK cell clones. Although not shown, the p46-mediated NK cell triggering was not induced by the (Fab′)2 fragment of anti-p46 mAb. These data indicate that cross-linking of p46 molecules is required in order to induce triggering of NK cell-mediated cytolytic activity. Indeed, lysis of FcγR− target cells was not incremented by anti-p46 mAbs. On the other hand, a partial inhibition mediated by anti-p46 mAb could be detected against some FcγR− target cells (including C1R and IGROV cell lines). At present it is not clear whether this inhibition reflects the interference with the interaction between p46 and its putative ligand expressed by these target cells.

Bottom Line: Upon mAb-mediated cross-linking, p46 molecules induced strong cell triggering leading to [Ca2+]i increases, lymphokine production, and cytolytic activity both in resting NK cells and NK cell clones.The p46-mediated induction of Ca2+ increases or triggering of cytolytic activity was downregulated by the simultaneous engagement of inhibitory receptors including p58, p70, and CD94/NKG2A.Both the unique cellular distribution and functional capability of p46 molecules suggest a possible role in the mechanisms of non-major histocompatibility complex-restricted cytolysis mediated by human NK cells.

View Article: PubMed Central - PubMed

Affiliation: Istituto di Istologia ed Embriologia Generale, Università di Genova, Genova, Italy.

ABSTRACT
Limited information is available on the surface molecules that are involved in natural killer (NK) cell triggering. In this study, we selected the BAB281 monoclonal antibody (mAb) on the basis of its ability to trigger NK-mediated target cell lysis. BAB281 identified a novel NK cell-specific surface molecule of 46 kD (p46) that is expressed by all resting or activated NK cells. Importantly, unlike the NK cell antigens identified so far, the expression of p46 was strictly confined to NK cells. Upon mAb-mediated cross-linking, p46 molecules induced strong cell triggering leading to [Ca2+]i increases, lymphokine production, and cytolytic activity both in resting NK cells and NK cell clones. The p46-mediated induction of Ca2+ increases or triggering of cytolytic activity was downregulated by the simultaneous engagement of inhibitory receptors including p58, p70, and CD94/NKG2A. Both the unique cellular distribution and functional capability of p46 molecules suggest a possible role in the mechanisms of non-major histocompatibility complex-restricted cytolysis mediated by human NK cells.

Show MeSH
Related in: MedlinePlus