Inmunologia (Barcelona, Spain : 1987)最新文献

The immune system is probably one of the most complex cellular organizations in the body. Its complexity is not superfluous, but rather it is required to fulfill the complicated purpose of the immune system, namely: the recognition of the diverse repertoire of microorganisms and pathogens; the detection of neoplastic lesions originating from a range of tissues; and, while executing these tasks, the maintenance of peripheral tolerance by suppressing detrimental responses against healthy tissues. Since they were discovered by R. Steinman et al. nearly 40 years ago, dendritic cells (DCs) have emerged to be critical players in conducting the immune response to fulfill these roles. Here, we provide a general view on some aspects of DC immunology, highlighting the crucial role that R. Steinman's research in the DC field has played during all those years. This review will also give an outline on DC research in the particular aspects that represent the focus of research groups in Spain (recently organized as the DC.esp working group within SEI). Firstly, some of the subtypes of DC will be described, particularly thymic DC and their role on tolerance; then the DC role in tolerance will be examined, followed by their implications in viral infections. Finally, antigen targeting DCs will be reviewed taking into account the crucial contributions made by R. Steinman et al. This chapter will end by reviewing some DCs based therapies in viral infections.

Aim

Haemophagocytic lymphohistiocytosis (HLH) is characterised by T cell and macrophage activation and excessive production of inflammatory cytokines. Genetic diagnosis is required to discriminate between primary forms (familial HLH, FHL), due to mutations in genes involved in cytolysis, and secondary forms. We aimed to analyse the genes coding for Munc13-4 (UNC13D) and syntaxin-11 (STX11) proteins in search of mutations that might explain HLH in 5 patients without perforin defects.

Materials and methods

Perforin expression was evaluated by flow cytometry, sCD25 was measured by ELISA and NK activity was investigated by the conventional functional assay. Coding regions and exons surroundings were sequenced for PRF1, UNC13D and STX11 genes.

Results

P1 and P2 developed severe early-onset HLH, P1 died at 6 months. P3, with a sister who died after HLH, responded well to treatment (HLH-2004), and had a second HLH episode two years later. P2 developed HLH at year 7 while in complete remission after lymphoblastic leukaemia. P4 and P5 were brothers who died at 5 and 6 years old due to an HLH and EBV mononucleosis infection. XLP was discarded because P4 was a girl. P1 and P3 showed mutations in UNC13D previously described as pathogenic. There were no changes in STX11.

Conclusions

UNC13D mutations were found in 50% of the HLH families without perforin defects and STX11 defects were not detected. These results agree with published series in which mutations in UNC13D explain up to 50% of FHL without PRF1 mutations, supporting a heterogeneous genetic background for this disease.

T lymphocyte antigen activation is facilitated by clustering of membrane glycosphingolipid-enriched microdomains (GEMs, lipid “rafts”) at the T cell/APC contact that is linked to changes in actin cytoskeleton and is one major mechanism of CD28 costimulation. Ligation of CD28 alone, or ligation of the CD28-like molecules CTLA-4 (CD152) and ICOS (CD278) induces actin polymerization with cell elongation and generation of lamellipodia and filopodia in T cells. These changes are dependent on Src, PI3-kinase, Vav, and Rho family GTPases. Whereas CD28 and CTLA-4 have been shown to be functional and physically associated with lipid rafts, the presence of ICOS in lipid rafts or its effect in raft clustering is not known. In this work, we have activated the T cell line D10 with anti-ICOS antibodies, alone or combined with anti-CD3 antibodies, bound or unbound to polystyrene microbeads or glass coverslips. The possible relationship of ICOS-induced changes in actin cytoskeleton to the ICOS localization in membrane rafts was then analyzed by fluorescence microscopy, or by immunoblot of detergent insoluble (“raft”) or soluble (“non-raft”) fractions of cell lysates. Our data show that ICOS promotes TCR/CD3 induction of raft clustering at the site of activation. However, ICOS, which, on its own, can induce accumulations of polymerized actin, is undetectable in membrane rafts, even when using CD3 or ICOS, ligands capable of inducing clear changes in the actin cytoskeleton.

Dendritic cells (DC) play a critical role in the regulation of the immune response. They are the main antigen presenting cells, due to their ability to capture, process and present antigens to T lymphocytes in an optimal way, and to generate specific immune responses. Subsequently, when methodological techniques allowed their in vitro purification and maturation, it was verified that they were able to activate several other immune cell subsets, like B lymphocytes, NK cells, macrophages or eosinophils, and even to induce immune tolerance. A deeper knowledge of their biology and functions has allowed the development of clinical trials in anti-tumour and anti-infective DC-based therapies, and also to induce post-transplant tolerance and to treat autoimmunity.

The group of major histocompatibility complex (MHC) alleles known as shared epitope (SE) is to date the strongest rheumatoid arthritis (RA) genetic risk factor. Many studies have shown that the measurement of anti-citrullinated peptides antibodies would be useful in the diagnosis and follow-up of RA.

Our aim is to determine the magnitude of the association between the possession of SE alleles and serum positive titres of antibodies against citrullinated peptides.

Our selection criteria included case–control or cohort studies, where data involving antibodies against citrullinated peptides and SE in RA patients were available. No date or language restrictions were imposed.

Bibliographical databases MEDLINE, Cochrane Database of Systematic Reviews and EMBASE were searched for pertinent literature. Two reviewers independently identified relevant citations and extracted data. Data extraction was then checked by two different reviewers.

Five published and one unpublished (own data) studies were included in the final meta-analysis. Overall, 2700 European descent RA patients were included in this meta-analysis. A significant association between SE and positive titres of serum antibodies against citrullinated peptides [OR(95% CI) = 3.19 (2.21–4.60)] was found.

Positive titres for antibodies against citrullinated peptides are threefold more frequent in RA patients who carry SE alleles than in those patients lacking them.