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Abstract. The cell surface receptor Fas (FasR, Apo-1, CD95) and its ligand (FasL) are mediators of apoptosis that have been shown to be implicated in the peripheral deletion of autoimmune cells, activation-induced T cell death, and one of the two major cytolytic pathways mediated by CD8 + cytolytic T cells. To gain further understanding of the Fas system, we have analyzed Fas and FasL expression during mouse development and in adult tissues. In developing mouse embryos, from 16.5 d onwards, Fas mRNA is detectable in distinct cell types of the developing sinus, thymus, lung, and liver, whereas FasL expression is restricted to submaxillary gland epithelial cells and the developing nervous system. Significant Fas and FasL expression were observed in several nonlymphoid cell types during embryogenesis, and generally Fas and FasL expression were not localized to characteristic sites of programmed cell death. In the adult mouse, RNase protection analysis revealed very wide expression of both Fas and FasL. Several tissues, including the thymus, lung, spleen, small intestine, large intestine, seminal vesicle, prostate, and uterus, clearly coexpress the two genes. Most tissues constitutively coexpressing Fas and FasL in the adult mouse are characterized by apoptotic cell turnover, and many of those expressing FasL are known to be immune privileged. It may be, therefore, that the Fas system is implicated in both the regulation of physiological cell turnover and the protection of particular tissues against potential lymphocyte-mediated damage.OPTOSIS is an active cell death process that takes place in a spectrum of physiological conditions such as embryonic development and normal cell turnover, but is also the mode of cell death resulting from CD8 ÷ T cell-mediated cytotoxicity (Steller, 1995). The mechanisms that regulate apoptotic cell death are therefore crucial for normal development and homeostasis.The Fas receptor (FasR, Apo-1 CD95) 1 is a cysteine-rich type I membrane protein belonging to the tumor necrosis factor (TNF) NGF receptor family, and shows high sequence similarities to CD27, CD30, CD40, and the lymphotoxin-13 receptor (Nagata and Golstein, 1995;Smith et al., 1994). Upon contact with cross-linking antibodies or the natural ligand (FasL), cells expressing Fas undergo apoptosis rapidly (Itoh et al., 1991;Trauth et al., 1989) by way Please address all correspondence to L

Astrocytomas are among the most common brain tumors that are usually fatal in their malignant form. They appear to progress without significant impedance from the immune system, despite the presence of intratumoral T cell infiltration. To date, this has been thought to be the result of T cell immunosuppression induced by astrocytoma-derived cytokines. Here, we propose that cell contact-mediated events also play a role, since we demonstrate the in vivo expression of

Graft-versus-host disease (GVHD) is the main complication after allogeneic bone marrow transplantation. Although the tissue damage and subsequent patient mortality are clearly dependent on T lymphocytes present in the grafted inoculum, the lethal effector molecules are unknown. Here, we show that acute lethal GVHD, induced by the transfer of splenocytes from C57BL/6 mice into sensitive BALB/c recipients, is dependent on both perforin and Fas ligand (FasL)-mediated lytic pathways. When spleen cells from mutant mice lacking both effector molecules were transferred to sublethally irradiated allogeneic recipients, mice survived. Delayed mortality was observed with grafted cells deficient in only one lytic mediator. In contrast, protection from lethal acute GVHD in resistant mice was exclusively perforin dependent. Perforin-FasL-deficient T cells failed to lyse most target cells in vitro. However, they still efficiently killed tumor necrosis factor alpha-sensitive fibroblasts, demonstrating that cytotoxic T cells possess a third lytic pathway.

Fas ligand (FasL, Apo-1L) is a member of the tumor necrosis factor protein family and binding to its receptor (Fas, Apo-1, CD95) triggers cell death through apoptosis. Ligand expression is restricted to cells with known cytolytic activity and found on hematopoietic cells of the T cell and natural killer lineage. Here we provide evidence that B lymphocytes can express FasL. Flow cytometric analysis revealed that FasL is expressed on the surface of B cells upon stimulation with either lipopolysaccharide or phorbol 12-myristate 13-acetate/ionomycin. FasL expression on activated B cells was confirmed by western blot and reverse transcriptase polymerase chain reaction analysis. FasL on B cells is functional since lipopolysaccharide-activated B lymphocytes derived from wild type, but not from gld mutant mice, were able to kill Fas-sensitive target cells. Our data suggest that the Fas system may contribute to the control of B cell homeostasis.

Clusterin is a serum glycoprotein endowed with cell aggregating, complement inhibitory, and lipid binding properties, and is also considered as a specific marker of dying cells, its expression being increased in various tissues undergoing programmed cell death (PCD). However, no study has so far directly shown that cells expressing clusterin in these tissues are actually apoptotic as defined by morphological and biochemical criteria.We have studied cellular clusterin gene expression in vitro using three different models of PCD: (a) ultraviolet B (UV-B) irradiation of human U937, HeLa, and A431 cell lines, (b) in vitro aging of human peripheral blood neutrophils (PMNs), and (c) dexamethasone-induced cell death of the human Iymphoblastoid cell line CEM-C7. In all three models, the classical morphological and biochemical features of PCD observed did not correlate with an increase, but with either a marked decrease or an absence of clusterin gene expression as assessed by Northern blot analysis. In situ hybridization of U937 and A431 cells after UV-B irradiation revealed, in addition, that only morphologically normal cells that are surviving continue to express the clusterin gene.Our results demonstrate that in the human myeloid, lymphoid, and epithelial cell types studied, clusterin gene expression is not a prerequisite to their death by apoptosis. In addition, and most interestingly, in situ hybridization of U937 and A431 cells revealed that only surviving cells express the clusterin gene after the induction of PCD, thus providing novel evidence suggesting that clusterin may be associated with cell survival within tissues regressing as a consequence of PCD. (J.

We report the case of an 80-year-old patient who had intense pruritus which did not respond to a 3-month treatment with topical corticosteroids. On dermoscopy examination of the excoriations, we found the typical dermoscopic aspect of the scabies mite at a distance. Dermoscopy allows identifying a triangular structure which corresponds to the anterior section of the mite including the mouth part and the 2 pairs of front legs. This aspect has been described as resembling a jetliner with its trail, a delta glider or a spermatozoid. Traditional diagnostic methods for scabies failed in this case because the mites were at a distance from the burrows. This was due to the fact that the reaction to the mite was less pronounced and the diagnosis is frequently missed. Dermoscopy is a useful tool for the diagnosis of scabies either as a diagnostic test or to guide the traditional diagnostic tests.

Switching from immunotherapy to targeted therapy in metastasized melanoma can be complicated by a cytokine release syndrome (CRS). CRS is a serious complication, which is induced by high levels of circulating cytokines, associated with T-cell engagement and proliferation, and results in a constellation of symptoms with variable organ involvement. We report 2 patients with BRAF V600 mutant melanoma who were previously treated with anti-PD-1±anti-LAG-3 antibodies and were switched to BRAF/MEK-inhibitors because of progressive disease. Both cases depict the complexity of interactions occurring during sequential treatment with immune checkpoint inhibitors and kinase inhibitors. Early identification and management of CRS is crucial to decrease its toxicity and improve safety of further drugs to be given in a therapeutic ladder.