Indeed, we observed an increased density of IgG plasma cells in the MZ and the reddish pulp, and augmented plasma IgG and IgM levels before 14?dpi

Indeed, we observed an increased density of IgG plasma cells in the MZ and the reddish pulp, and augmented plasma IgG and IgM levels before 14?dpi. model for HIV-1 contamination in humans C showing that infectious brokers have developed strategies to subvert MZ B-cell functions. In these two experimental models, we observed that two microbial superantigens for B-cells (protein A from and protein L from and (Attanavanich and Kearney, 2004). Specifically, MZ B-cells can mount rapid and efficient primary responses to soluble protein Ag and have an extraordinary ability to promote T-cell proliferation and cytokine production after immunization with protein Ag. Within a few hours of Ag priming, MZ B-cells are much superior to FO B-cells in the activation of naive CD4+ T-cells showed that MZ B-cells directly associate with blood-borne spirochetes and are activated to produce pathogen-specific IgM within 72?h of contamination (Belperron et al., 2005). When mice were depleted from MZ B-cells to determine their contribution to host defense against by TLR4 and TLR9 ligands to proliferate and secrete Ab (Whitlock and Watson, 1979). and promote their release from your MZ, thus potentially accelerating the kinetics of the Ag-specific IgM response (Rubtsov et al., 2008). In response to TLR agonists, MZ Xylometazoline HCl B-cells proliferate and exhibit a phenotypic maturation process characterized by an increased expression of MHC class II, CD40, and CD86 molecules. Xylometazoline HCl According to the TLR agonist used, they also display a different cytokine profile (Bialecki et al., 2009). The fact that MZ B-cells are well equipped in TLRs and that their stimulation prospects to cell proliferation, maturation (i.e., cytokine production) and Ab production (Rubtsov et al., 2008) further supports the conclusion that they play a role as innate sensors in MZ B cell-mediated immune responses. Strikingly, MZ B-cells are able to promote optimal immune responses by interacting with other cell types. For instance, they can transport immune complexes to follicular DCs and deposit them on their surface, or process Ag for direct presentation on MHC class II molecules to na?ve CD4+ T-cells (Martin and Kearney, 2002; Attanavanich and Kearney, 2004). Further evidence comes from studies of invariant NKT (iNKT) cells, a subset of NKT cells that identify exogenous and self glyco/lipid Ags offered by the non-classical class I molecule CD1d expressed on Ag presenting cells (APC; Bendelac et al., 2007). Upon main activation, iNKT cells produce large amounts of immunoregulatory cytokines, including IFN- and IL-4 that lead to downstream activation of DC, NK cells, B-cells, and standard T-cells (Bendelac et al., 2007). In the mouse, iNKT cells localize in the splenic B-cell area, including the MZ. In the presence of accessory cells (DC), MZ B-cells stimulate the release of both IFN- and IL-4 by iNKT cells, strongly suggesting that MZ B-cells have the potential to condition iNKT cell Xylometazoline HCl functions (Bialecki et al., 2009). The observation that MZ B-cells play a role in iNKT cell activation and and polysaccharide dextran by MZMs (Lanoue et al., 2004; Birjandi et al., 2011). Importantly, the dialog between MZ B-cells and MZM is essential to maintain the MZ structure and to allow efficient immune responses (Karlsson et al., 2003). For example, once MZM bind pathogen, they establish direct cellCcell interactions with MZ B-cells that are required for potent responses (Chen et al., 2005), allowing the clearance of and (Odermatt et al., 1991; Aichele et al., 2003). In another model system, MZ B-cells were found to regulate the expression of molecules on macrophages that are important for trapping Ag, which, in turn, is required for Ag capture by the B-cells, thus modulating MZM functions that Xylometazoline HCl are important Rabbit Polyclonal to Lamin A (phospho-Ser22) to protect against lethal contamination (You et al., 2011). Consistently, the decreased frequency of MZM and MZ B-cells seen Xylometazoline HCl in aged mice correlates with disruption in the marginal sinus and reduced capacity to bind and obvious pathogen-like particles (Birjandi et al., 2011). Thus, MZ B-cells not only provide a link between the innate and adaptive immune responses, but they also function as regulatory cells that control the phenotype and function of other cells involved in the acute innate immune response. Human MZ B-Cells Studies of the Ig genes expressed by MZ B-cells of normal untreated, non-intentionally immunized rodents revealed that this.