Lipopolysaccharide polyclonal activation

Switching to classes other than IgD is most obvious in activated B cells. Extensive studies have been performed on mouse B cells that have been polyclonally activated by bacterial lipopolysaccharide (LPS) [2,16-18] or by both LPS and switch factors , i.e. certain lymphokines produced by T lymphocytes [6-9]. Antigen stimulation in vitro (e.g. [19]) and mitogenic stimulation of human B cells (e.g. [20])... 

In assays to assess the immunomodulatory activity of a polysaccharide isolated from white mulberry root bark, the compound was found to enhance proliferation of splenic lymphocytes in a synergistic manner in the presence of mitogens. However, the compound suppressed primary IgM antibody production from B cells, which was activated with lipopolysaccharide, a polyclonal activator, or immunized with a T-cell-dependent antigen, sheep red blood cells (Kim et al. 2000). 

A lipopolysaccharide (LPS) is any compound consisting of covalently linked lipids and polysaccharides. The term is used more frequently to denote a cell wall component from Gram-negative bacteria. LPS has endotoxin activities and is a polyclonal stimulator of B-lymphocytes. 

Rheumatoid factors of the IgM and IgG classes have been shown to form immune complexes in serum or joint fluid either by self-association (K17, M4, M26, P13, Sll, W21) or by reaction with native IgG (C4, K17, M4, N5, Sll, W21, W22), and these appear to be the predominant immune complex material in rheumatoid arthritis (C4, Gl, K17, M4, M26, N5, Sll, W21, W22). The primary cause of rheumatoid factor production in rheumatoid arthritis is unknown. However, rheumatoid factors are known to be present in other diseases associated with chronic antigenic stimulation (C14, M14) and can be induced in vitro by stimulation with antigens, autologous aggregated IgG, anti-idiotype reagents, and polyclonal B cell activators such as lipopolysaccharide and Epstein-Barr virus (C4, Dll, F6, F7, Gil, 16, P10, S24). Rheumatoid factors, including IgG rheumatoid factors which form selfassociating intermediate-sized (11-19 S) complexes, play a major role in... 

FIGURE 3 (top) Mean arterial blood pressure (MAP) and (bottom) iNOS activity in the lungs at 240 min after lipopolysaccharide (LPS) (10 mg/kg) in vehicle-treated rats (Control), rats pretreated with a polyclonal antibody against lipocortin 1 (Anti-lipo 1), rats in the presence of dexamethasone (3 mg/kg intravenously for 60 min) pretreatment (DEX), and dexamethasone-treated rats that had also been pretreated with a polyclonal antibody against lipocortin 1 (DEXAnti-lipo 1) ( = 5-6). Data are expressed as the means SEM of n observations. 

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