Allotypes of the natural killer (NK) cell receptor KIR3DL1 vary in both NK cell expression patterns and inhibitory capacity upon binding to their ligands, HLA-B Bw4 molecules, present on target cells. Using a sample size of over 1,500 human immunodeficiency virus (HIV)+ individuals, we show that various distinct allelic combinations of the KIR3DL1 and HLA-B loci significantly and strongly influence both AIDS progression and plasma HIV RNA abundance in a consistent manner. These genetic data correlate very well with previously defined functional differences that distinguish KIR3DL1 allotypes. The various epistatic effects observed here for common, distinct KIR3DL1 and HLA-B Bw4 combinations are unprecedented with regard to any pair of genetic loci in human disease, and indicate that NK cells may have a critical role in the natural history of HIV infection.

Summary Hepatocellular carcinoma (HCC) is the second most common cause of cancer related death. Non-alcoholic fatty liver disease (NAFLD) affects a large proportion of the US population and is considered a metabolic predisposition to liver cancer 1-5. However, the role of adaptive immune responses in NAFLD-promoted HCC is largely unknown. Here, we show that dysregulation of lipid metabolism in NAFLD causes a selective loss of intrahepatic CD4+ but not CD8+ T lymphocytes leading to accelerated hepatocarcinogenesis. We also found that CD4+ T lymphocytes have greater mitochondrial mass than CD8+ T lymphocytes and generate higher levels of mitochondrially-derived reactive oxygen species (ROS). Disruption of mitochondrial function by linoleic acid, a fatty acid accumulated in NAFLD, causes more oxidative damage than other free fatty acids such as palmitic acid, and mediates selective loss of intrahepatic CD4+ T lymphocytes. In vivo blockade of ROS reversed NAFLD-induced hepatic CD4+ T lymphocyte decrease and delayed NAFLD-promoted HCC. Our results provide an unexpected link between lipid dysregulation and impaired anti-tumor surveillance.

Interleukin-2 (IL-2) signaling requires the dimerization of the IL-2 receptor beta.(IL-2R beta) and common gamma (gamma c) chains. Mutations of gamma c can result in X-linked severe combined immunodeficiency (XSCID). IL-2, IL-4, IL-7 (whose receptors are known to contain gamma c), and IL-9 (whose receptor is shown here to contain gamma c) induced the tyrosine phosphorylation and activation of the Janus family tyrosine kinases Jak1 and Jak3. Jak1 and Jak3 associated with IL-2R beta and gamma c, respectively; IL-2 induced Jak3-IL-2R beta and increased Jak3-gamma c associations. Truncations of gamma c, and a gamma c, point mutation causing moderate X-linked combined immunodeficiency (XCID), decreased gamma c-Jak3 association. Thus, gamma c mutations in at least some XSCID and XCID patients prevent normal Jak3 activation, suggesting that mutations of Jak3 may result in an XSCID-like phenotype.

SummarySince the discovery of triggering receptor expressed on myeloid cells (TREM)-1 in 2000, evidence documenting the profound ability of the TREM and TREM-like receptors to regulate inflammation has rapidly accumulated. Monocytes, macrophages, myeloid dendritic cells, plasmacytoid dendritic cells, neutrophils, microglia, osteoclasts and platelets all express at least one member of the TREM family, underscoring the importance of these proteins in the regulation of innate resistance. Recent work on the TREM family includes: characterization of a new receptor expressed on plasmacytoid dendritic cells; definition of a key role for TREM in inflammatory bowel disease and multiple sclerosis; an expanded list of diseases associated with the release of soluble forms of TREM proteins; and identification of the first well characterized TREM ligand: B7-H3, a ligand for TREM-like Transcript (TLT)-2. Moreover, analysis of TREM signaling has now identified key regulatory components and defined pathways that may be responsible for the complex functional interactions between the TREM and toll-like receptors. In addition, there is expanding evidence of a role for TREM in the regulation of integrin function via Plexin-A1. Together these new findings define the TREM and TREM-like receptors as pluripotent modifiers of disease through the integration of inflammatory signals with those associated with leukocyte adhesion.

T cell receptor (TCR) signaling requires activation of Zap-70 and Src family tyrosine kinases, but requirements for other tyrosine kinases are less clear. Combined deletion in mice of two Tec kinases, Rlk and Itk, caused marked defects in TCR responses including proliferation, cytokine production, and apoptosis in vitro and adaptive immune responses to Toxoplasma gondii in vivo. Molecular events immediately downstream from the TCR were intact in rlk-/-itk-/- cells, but intermediate events including inositol trisphosphate production, calcium mobilization, and mitogen-activated protein kinase activation were impaired, establishing Tec kinases as critical regulators of TCR signaling required for phospholipase C-gamma activation.

Impaired immune responses occur frequently in cancer patients or in tumor-bearing mice, but the mechanisms of the tumor-induced immune defects remain poorly understood. In an in vivo murine colon carcinoma model (MCA-38), animals bearing a tumor longer than 26 days develop CD8+ T cells with impaired cytotoxic function, decreased expression of the tumor necrosis factor-alpha and granzyme B genes, and decreased ability to mediate an antitumor response in vivo. T lymphocytes from tumor-bearing mice expressed T cell antigen receptors that contained low amounts of CD3 gamma and completely lacked CD3 zeta, which was replaced by the Fc epsilon gamma-chain. Expression of the tyrosine kinases p56lck and p59fyn was also reduced. These changes could be the basis of immune defects in tumor-bearing hosts.

A variant 35 kb upstream of the HLA-C gene (-35C/T) was previously shown to associate with HLA-C mRNA expression level and steady-state plasma HIV RNA levels. We genotyped this variant in 1,698 patients of European ancestry with HIV. Individuals with known seroconversion dates were used for disease progression analysis and those with longitudinal viral load data were used for viral load analysis. We further tested cell surface expression of HLA-C in normal donors using an HLA-C-specific antibody. We show that the -35C allele is a proxy for high HLA-C cell surface expression, and that individuals with high-expressing HLA-C alleles progress more slowly to AIDS and control viremia significantly better than individuals with low HLA-C expressing alleles. These data strongly implicate high HLA-C expression levels in more effective control of HIV-1, potentially through better antigen presentation to cytotoxic T lymphocytes or recognition and killing of infected cells by natural killer cells.Correspondence should be addressed to M.C. (carringm@mail.nih.gov). Note: Supplementary information is available on the Nature Genetics website. Reprints and permissions information is available online at http://npg.nature.com/reprintsandpermissions/. AUTHOR CONTRIBUTIONS NIH Public Access Author ManuscriptNat Genet. Author manuscript; available in PMC 2010 December 1. Recently, however, a scan for genetic variants that influence the control of viral load indicated that a dimorphism 35 kb upstream of the HLA-C gene (-35C/T) had one of the two strongest genome-wide effects on the level of plasma viremia in early, established HIV infection as measured by viral load set-point, although no significant association of this variant was observed with progression to a CD4 cell count of <350 (ref.2 ). Notably, the -35C variant that associates with low viral load has also been shown to associate with high HLA-C mRNA levels in a codominant manner among a group of individuals of European ancestry 12,13 , although whether it associates with cell surface expression has not been tested. These findings suggest that certain HLA-C allotypes might have a primary role in restricting HIV replication through innate and/or acquired immune mechanisms that have previously been overlooked. Here we present data from 1,698 European American individuals, indicating that high levels of HLA-C confer strong protection early in the course of HIV infection and this early protection of high HLA-C extends to some extent into chronic infection. We propose a model in which highexpression HLA-C alleles might confer better innate and/or acquired immune responses than low-expression HLA-C alleles. RESULTS Effect of-35 on mean viral loadThe effect of -35 genotypes on mean plasma HIV load (mVL) measurements was tested in a group of 935 seroincident European American individuals (see Online Methods). Each individual was categorized into one of three groups based on their mVL (<2,000, 2,000-10,000 and >10,000 mean viral RNA copies per ml plasma), and the frequency of ea...

Interleukin-2 is an autocrine growth factor for T cells which also activates other cells including B cells and natural killer cells. The subunits of the interleukin-2 receptor (IL-2R) lack intrinsic enzymatic activity, but protein tyrosine phosphorylation is a critical event following ligand binding and src family kinases, such as Lck, are known to be activated by IL-2 (refs 5-9). However, IL-2 signalling can occur in the absence of receptor interaction with Lck, suggesting that other protein tyrosine kinases might be important. Here we report that a new member of the Janus family of kinases (Jak-3) is coupled to the IL-2R in human peripheral blood T cells and natural killer cells.