title: Human NK cell response to pathogens.
abstract: NK cells represent important effectors of the innate immunity in the protection of an individual from microbes. During an NK-mediated anti-microbial response, the final fate (survival or death) of a potential infected target cell depends primarily on the type and the number of receptor/ligand interactions occurring at the effector/target immune synapse. The identification of an array of receptors involved in NK cell triggering has been crucial for a better understanding of the NK cell biology. In this context, NCR play a predominant role in NK cell activation during the process of natural cytotoxicity. Regarding the NK-mediated pathogen recognition and NK cell activation, an emerging concept is represented by the involvement of TLRs and activating KIRs. NK cells express certain TLRs in common with other innate cell types. This would mean that specific TLR ligands are able to promote the simultaneous and synergistic stimulation of these innate cells, providing a coordinated mechanism for regulating the initiation and amplification of immune responses. Evidences have been accumulated indicating that viral infections may have a significant impact on NK cell maturation, promoting the expansion of phenotypically and functionally aberrant NK cell subpopulations. For example, during chronic HIV-infection, an abnormal expansion of a dysfunctional CD56neg NK cell subset has been detected that may explain, at least in part, the defective NK cell-mediated antiviral activity. An analogous imbalance of NK cell subsets has been detected in patients receiving HSCT to cure high risk leukemias and experiencing HCMV infection/reactivation. Remarkably, NK cells developing after CMV reactivation may contain "memory-like" or "long-lived" NK cells that could exert a potent anti-leukemia effect.
authors.affiliation: DI.ME.S. Dipartimento di Medicina Sperimentale and Centro di Eccellenza per la Ricerca Biomedica, Università di Genova, Genova, Italy.
authors.forename: Mariella
authors.initials: M
authors.lastname: Della Chiesa
authors.affiliation: DI.ME.S. Dipartimento di Medicina Sperimentale and Centro di Eccellenza per la Ricerca Biomedica, Università di Genova, Genova, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Marcenaro
authors.affiliation: DI.ME.S. Dipartimento di Medicina Sperimentale and Centro di Eccellenza per la Ricerca Biomedica, Università di Genova, Genova, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Sivori
authors.affiliation: DI.ME.S. Dipartimento di Medicina Sperimentale and Centro di Eccellenza per la Ricerca Biomedica, Università di Genova, Genova, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Carlomagno
authors.affiliation: DI.ME.S. Dipartimento di Medicina Sperimentale and Centro di Eccellenza per la Ricerca Biomedica, Università di Genova, Genova, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Pesce
authors.affiliation: DI.ME.S. Dipartimento di Medicina Sperimentale and Centro di Eccellenza per la Ricerca Biomedica, Università di Genova, Genova, Italy. Electronic address: alemoret@unige.it.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Moretta
mesh_terms: D003587:Cytomegalovirus / Q000276:immunology; D003586:Cytomegalovirus Infections / Q000276:immunology / Q000378:metabolism; D015658:HIV Infections / Q000276:immunology / Q000378:metabolism; D054884:Host-Pathogen Interactions / Q000276:immunology*; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism*; D051193:Toll-Like Receptors / Q000378:metabolism
chemical_list: D051193:Toll-Like Receptors
keywords: Anti-viral response; BCG; HCMV; HIV; Natural killer cells; Toll-like receptors