Macrophage colony stimulating factor (MCSF) influences proliferation and survival of mononuclear phagocytes through the CSF-1 receptor. The DAP12 adaptor protein, which transduces signals emanating from various myeloid receptors, is critical for mononuclear phagocyte function. DAP12-mutant mice and humans show defects in osteoclasts and microglia and exhibit brain and bone abnormalities. Here, we demonstrated that DAP12 deficiency impairs MCSF-induced macrophage proliferation and survival in vitro. In addition, DAP12-deficient mice show fewer microglia in defined central nervous system areas, and DAP12-deficient progenitors regenerate myeloid cells inefficiently following BM transplantation. MCSF-CSF1-R signaling induced stabilization and nuclear translocation of β-catenin, which activates cell cycle genes. DAP12 was essential for phosphorylation and nuclear accumulation of β-catenin. These results outline a mechanistic explanation for the multiple defects in DAP12-deficient mononuclear phagocytes.

Mutations decreasing function of the Fas death receptor cause the autoimmune lymphoproliferative syndrome (ALPS) with autoimmune manifestations, spleen/ lymph node enlargement, and expansion of CD4/CD8-negative T cells. Dianzani Autoimmune Lymphoproliferative Disease (DALD) is a variant lacking this expansion. Perforin is involved in cell-mediated cytotoxicity and its biallelic mutations cause familial hemophagocytic lymphohistiocytosis (HLH). We previously described an ALPS patient carrying heterozygous mutations of the Fas and perforin genes and suggested that they concurred in ALPS. This work extends the analysis to 14 ALPS, 28 DALD, and 816 controls, and detects an N252S amino acid substitution in 2 ALPS, and an A91V amino acid substitution in 6 DALD. N252S conferred an OR ‫؍‬ 62.7 (P ‫؍‬ .0016) for ALPS and A91V conferred an OR ‫؍‬ 3 (P ‫؍‬ .016) for DALD. Copresence of A91V and variations of the osteopontin gene previously associated with DALD conferred an OR ‫؍‬ 17 (P ‫؍‬ .0007) for DALD.In one N252S patient, NK activity was strikingly defective in early childhood, but became normal in late childhood. A91V patients displayed lower NK activity than controls. These data suggest that perforin variations are a susceptibility factor for ALPS/DALD development in subjects with defective Fas function and may influence disease expression. IntroductionFas is a death receptor belonging to the tumor necrosis factor receptor (TNFR) superfamily and induces cell death upon triggering by FasL. [1][2][3] In the immune response, it is highly expressed by activated effector lymphocytes and is involved in switching off the immune response, limiting clonal expansion of lymphocytes, and favoring peripheral tolerance. Moreover, FasL is expressed by cytotoxic T cells and NK cells and is involved in killing of target cells expressing Fas. Fas induces cell apoptosis by triggering a cascade of caspases through 2 partly interconnected pathways: the extrinsic pathway involves caspase-8-mediated direct activation of the cascade, whereas the intrinsic pathway proceeds through mitochondrial release of cytochrome c and activation of caspase-9. Both pathways converge in the activation of effector caspases, such as caspase-3, -6, and -7. [1][2][3] Defective Fas function leads to the unwanted accumulation of lymphocytes and favors autoimmunity possibly by impairing the switching off of autoreactive lymphocytes. This has been shown in the autoimmune lymphoproliferative syndrome (ALPS), an inherited disease characterized by (1) defective function of Fas, (2) autoimmune manifestations that predominantly involve blood cells, (3) polyclonal accumulation of lymphocytes in the spleen and lymph nodes with lymphoadenomegaly and/or splenomegaly, and (4) expansion of TCR␣␤ ϩ CD4/CD8 double-negative (DN) T cells in the peripheral blood. Moreover, ALPS patients are predisposed to develop lymphomas in adulthood. 3-11 ALPS is generally due to deleterious mutations of the Fas gene (TNFRSF6) and is classified as ALPS type-Ia, but rare mutations of other ge...

Background: Autoimmune lymphoproliferative syndrome (ALPS) is a rare inherited disorder characterized by defective function of Fas, autoimmune manifestations that predominantly involve blood cells, polyclonal accumulation of lymphocytes in the spleen and lymph nodes with lymphoadenomegaly and/or splenomegaly, and expansion of TCRαβ+ CD4/CD8 double-negative (DN) T cells in the peripheral blood. Most frequently, it is due to Fas gene mutations, causing ALPS type Ia (ALPS-Ia). However, other mutations, namely of the FasL gene (ALPS-Ib) and the caspase-10 gene (ALPS-II) are occasionally detected, whereas some patients do not present any known mutations (ALPS-III). Recently, mutations of the NRAS gene have been suggested to cause ALPS-IV.

No abstract

KSR1 is a mitogen-activated protein (MAP) kinase scaffold that enhances the activation of the MAP kinase extracellular signal-regulated kinase (ERK). The function of KSR1 in NK cell function is not known. Here we show that KSR1 is required for efficient NK-mediated cytolysis and polarization of cytolytic granules. Singlecell analysis showed that ERK is activated in an all-or-none fashion in both wild-type and KSR1-deficient cells. In the absence of KSR1, however, the efficiency of ERK activation is attenuated. Imaging studies showed that KSR1 is recruited to the immunological synapse during T-cell activation and that membrane recruitment of KSR1 is required for recruitment of active ERK to the synapse.

The current investigation provided the first data concerning the frequency of ponticulus posticus in Italy: further studies are needed to widen the sample, verify possible regional variations and improve the analysis by more advanced radiological examinations such as CT and cone beam CT scans.

OBJECTIVE-Perforin plays a key role in cell-mediated cytotoxicity. Mutations of its gene, PRF1, cause familial hemophagocytic lymphohistiocytosis but have also been associated with lymphomas and the autoimmune/lymphoproliferative syndrome. The aim of this work was to investigate the role of PRF1 variations in type 1 diabetes.RESEARCH DESIGN AND METHODS-We typed for the N252S and A91V variations in an initial population of 352 type 1 diabetic patients and 816 control subjects and a second population of 365 patients and 964 control subjects. Moreover, we sequenced the coding sequence and intron-exons boundaries in 200 patients and 300 control subjects.RESULTS-In both cohorts, allelic frequency of N252S was significantly higher in patients than in control subjects (combined cohorts: 1.5 vs. 0.4%; odds ratio 6.68 [95% CI 1.83-7.48]). Sequencing of the entire coding region detected one novel mutation in one patient, causing a P477A amino acid change not detected in 199 patients and 300 control subjects. Typing for HLA-DQA1 and DQB1 alleles showed that type 1 diabetespredisposing DQ␣/DQ␤ heterodimers were less frequent in patients carrying N252S or P477A than in those carrying wild-type PRF1. We previously found that natural killer (NK) activity is not decreased in most N252S heterozygotes, but we detected one whose NK activity was normal at the age of 12 but strikingly low in early childhood. Here, we discovered that NK function was low in three heterozygotes in early childhood, one homozygous adult, and in the subject carrying P477A.CONCLUSIONS-These data suggest that N252S and possibly other PRF1 variations are susceptibility factors for type 1 diabetes development.

Human ICOS is a T cell costimulatory molecule supporting IL10 secretion. A pilot study investigating variations of the ICOS gene 3'UTR detected 8 polymorphisms forming three haplotypes (A, B, C). Haplotype-A and -C displayed the highest difference. Activated T cells from healthy AA homozygotes expressed significantly less ICOS and secreted more IL10 than AC heterozygotes, whereas AB heterozygotes displayed intermediate levels. Analysis of 441 multiple sclerosis patients and 793 controls showed that frequency of AA homozygosity was significantly lower in MS patients with relapsing-remitting onset (N=416) than in controls (OR=0.70). Moreover, AA patients with relapsing-remitting onset had lower relapse rate and multiple sclerosis severity score than non-AA patients.