|
| ||
|
|
||
Cell-dependent Immune Response (cell-dependent + immune_response)
Selected AbstractsPolymerase,, is up-regulated during the T,cell-dependent immune response and its deficiency alters developmental dynamics of spleen centroblastsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 5 2005Daniel Lucas Abstract Mammalian DNA polymerase,, (Pol,), preferentially expressed in secondary lymphoid organs, is shown here to be up-regulated in germinal centers after immunization. Alternative splicing appears to be part of Pol, regulation during an immune response. We generated Pol,-deficient mice that are viable and show no anatomical malformation or serious alteration in lymphoid populations, with the exception of an underrepresentation of the B,cell compartment. Young and aged homozygous Pol,,/, mice generated similar immune responses after immunization with the hapten (4-hydroxy-3-nitrophenyl)acetyl (NP) coupled to chicken gammaglobulin (CGG), compared with their wild-type littermates. Nonetheless, the kinetics of development of the centroblast population showed significant differences. Hypermutation analysis of the rearranged heavy chain intron region in centroblasts isolated from NP-CGG-immunized Pol,,/, mice showed a similar quantitative and qualitative somatic mutation spectrum, but a lower representation of heavily mutated clones. These results suggest that although it is not a critical partner, Pol, modulates the in vivo somatic hypermutation process. [source] N-terminal destruction signals lead to rapid degradation of the major histocompatibility complex class II transactivator CIITAEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2003Felix Schnappauf Abstract Major histocompatibility complex (MHC) class II molecules play an essential role for the cellular immune response by presenting peptide antigens to CD4+ T cells. MHC class II molecules and genes show a highly complex expression pattern, which is orchestrated through a master regulatory factor, called CIITA (class II transactivator). CIITA controls MHC class II expression not only qualitatively, but also quantitatively, and has therefore a direct influence on the CD4 T cell-dependent immune response. CIITA is itself tightly regulated not only on the transcriptional level, but as we show here also on the protein level. CIITA is subjected to a very rapid protein turnover and shows a half-life of about 30,min. Inhibition of degradation by proteasome inhibitors and the identification of ubiquitylated CIITA intermediates indicate that the degradation of CIITA is mediated by the ubiquitin-proteasome system. We identified two regions mediating degradation within the N-terminal domain of CIITA. N-terminal fusions or deletions stabilized CIITA, indicating that the N termini contribute to degradation. Several non-functional CIITA mutants are partially stabilized, but we provide evidence that transcriptional activity of CIITA is not directly linked to degradation. [source] Development of nephritis but not sialadenitis in autoimmune-prone BAFF transgenic mice lacking marginal zone B cellsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 9 2006Carrie Abstract B cell-activating factor belonging to the TNF family (BAFF) is a B cell survival factor required for B cell maturation. BAFF transgenic (Tg) mice develop autoimmune disorders characterized by autoantibody production, which leads to nephritis and salivary gland destruction (sialadenitis), features reminiscent of systemic lupus erythematosus and Sjögren's syndrome (SS), respectively. Disease in BAFF Tg mice correlates with the expansion of the marginal zone (MZ) B cell compartment and the abnormal presence of MZ-like B cells in the blood, LN and inflamed salivary glands, suggesting a role for these cells in BAFF-induced autoimmunity. Lymphotoxin-, (LT,)-deficient mice show disrupted splenic architecture, lack MZ B cells and some peripheral LN, and are unable to mount T cell-dependent immune responses. BAFF Tg mice lacking LT, (LT,,-BTg) retained these defects, yet still developed nephritis associated with the presence of B-1 B cells in the kidneys. However, in contrast to old BAFF Tg mice, aging LT,,-BTg mice no longer developed sialadenitis. Thus, autoimmune disorders in BAFF Tg mice are possibly events coordinated by MZ and B-1 B cells at separate anatomical sites. [source] Splenic function and IgM-memory B cells in Crohn's disease patients treated with infliximabINFLAMMATORY BOWEL DISEASES, Issue 5 2008Antonio Di Sabatino MD Abstract Background: Under experimental chronic inflammation, tumor necrosis factor (TNF)-, plays a role in damaging spleen marginal zone. This latter has a crucial function in mounting B cell-dependent immune responses against infections by encapsulated bacteria. In Crohn's disease (CD), a chronic inflammatory disorder where TNF-, is centrally involved, impaired splenic function may increase the susceptibility to bacterial infections. On this basis, we aimed to investigate the influence of anti-TNF therapy on splenic function in CD patients. Methods: Peripheral blood samples were obtained from 15 CD patients before and after treatment with infliximab administered at weeks 0, 2, and 6 at a dose of 5 mg/kg. Counting of erythrocytes with membrane abnormalities (pitted red cells) was used as an indicator of splenic function. Multicolor flow cytometry was performed to analyze circulating B cells. Results: A substantial clinical improvement in 10 of the 15 CD patients was associated with a significant reduction of pitted red cells (from median 6.0% to 3.6%; P < 0.01) after 10 weeks of treatment. In responder patients the improvement of splenic function was accompanied by a parallel increase of circulating IgM-memory B cells (from median 6.9% to 13.3%; P < 0.005). Splenic function was not ameliorated in nonresponder patients. Conclusions: Splenic function improved in CD patients who responded to infliximab and was accompanied by a concomitant restoration of the IgM-memory B cell pool responsible for the protection against encapsulated bacteria. Restoration of splenic function after infliximab treatment is intriguing and requires further investigation. (Inflamm Bowel Dis 2008) [source] | ||||||||||