title: Modulation of 2B4 (CD244) activity and regulated SAP expression in human NK cells.
abstract: The adapter protein SAP is important for the signal transduction of the family of SLAM-related receptors (SRR), which have important immune-modulating functions. The importance of SAP and SRR for a functional immune reaction becomes obvious in patients suffering from X-linked lymphoproliferative disease, which is characterized by non-functional SAP. Here we investigate the regulation of SAP expression in human NK cells. We demonstrate that SAP mRNA expression and protein levels are low in freshly isolated resting NK cells. IL-2 stimulation leads to an up-regulation of SAP expression, which can be enhanced by IL-12, the stimulation of TLR3 by polyinosinic-polycytidylic acid (poly(I:C))and to a lesser extent by IFN-alpha. EAT-2, a SAP-related adapter protein, is already detectable in resting NK cells and does not change its expression after IL-2 stimulation. The regulation of SAP has functional consequences for the stimulation of NK cell cytotoxicity by 2B4. In resting NK cells, 2B4 stimulation can only enhance NK cell lysis when co-triggered with other activating NK cell receptors. In IL-2-activated NK cells with high SAP expression the triggering of 2B4 alone is sufficient to induce NK cell cytotoxicity, demonstrating a correlation between the regulated SAP expression and the function of 2B4.
authors.affiliation: Institute for Immunology, University Heidelberg, Heidelberg, Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Endt
authors.forename: Philipp
authors.initials: P
authors.lastname: Eissmann
authors.forename: Sabrina C
authors.initials: SC
authors.lastname: Hoffmann
authors.forename: Stephan
authors.initials: S
authors.lastname: Meinke
authors.forename: Thomas
authors.initials: T
authors.lastname: Giese
authors.forename: Carsten
authors.initials: C
authors.lastname: Watzl
mesh_terms: D015703:Antigens, CD / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D003601:Cytotoxicity Tests, Immunologic; D005786:Gene Expression Regulation / Q000276:immunology*; D006801:Humans; D007376:Interleukin-2 / Q000502:physiology; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism*; D008213:Lymphocyte Activation / Q000276:immunology; D011956:Receptors, Cell Surface / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D011971:Receptors, Immunologic / Q000378:metabolism*; D000071176:Signaling Lymphocytic Activation Molecule Family; D000071177:Signaling Lymphocytic Activation Molecule Family Member 1; D014162:Transfection
chemical_list: D015703:Antigens, CD; C084093:CD244 protein, human; D007376:Interleukin-2; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D000071176:Signaling Lymphocytic Activation Molecule Family; D000071177:Signaling Lymphocytic Activation Molecule Family Member 1