摘要:

Endotoxins (lipopolysaccharides, LPS) are biologically active substances present in the outer membrane of gram-negative bacteria. They induce a spectrum of biological effects which may be harmful or beneficiary for the host.Lipid A is the biologically active part of the LPS molecule. This was demonstrated using soluble forms of lipid A and more recently confirmed further by employing synthetic lipid A. LPS administered into experimental animals circulates as LPS/HDL complex and is cleared from the blood mainly into the liver and spleen. In the liver LPS undergoes partial deacylation however without a loss of toxic activity. Its excretion is effected mainly via the bile into the gut.The lethal toxicity and tolerance inducing properties of LPS are mediated by macrophages through tumor necrosis factorα(TNFα), which is probably the most important endogenous mediator of the lethal effects of LPS. The lethal toxicity of LPS may be completely inhibited by anti-TNFαantibodies.

ISSN:0883-0185    

DOI:10.3109/08830189009056632

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

ISSN:0883-0185    

DOI:10.3109/08830189009056633

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

The role of bacterial lipopolysaccharides (LPS) has been evaluated for their influence on the human T cell-mediated anti-Salmonella typhiactivity. In nonendemic areas for salmonellosis this activity is exerted by CD4+lymphocytes armed by IgA, whereas in endemic zones besides these cells also CD8+lymphocytes armed by IgG display an elevated anti bacterial activity. These results suggest that, in endemic regions, continuous antigenic challenge and, in particular, that exerted by lipid A (the active moiety of LPS) may play a role in triggering this activity.In other series of experiments, pretreatment of endemic peripheral blood lymphocytes (PBL) with smooth and rough (Rb and Re) forms ofSalmonellaLPS leads to the inhibition of antibacterial activity. In this respect, Re-LPS, which contains lipid A covalently linked to the core-chetodeoxyoctonate, gives rise to the maximum of inhibition.Finally, fractionation of PBL by means ofS. minnesotaR345 (Rb) cytoadherence has led to the conclusion that anti bacterial activity is present in the Rb-unbound population, thus indicating that bacterial adherence to PBL is a distinct phenomenon from natural anti-S. typhiactivity.The overall results suggest that lipid A is able to modulate the expression of antibacterial activity exerted by human peripheral blood T cells.

ISSN:0883-0185    

DOI:10.3109/08830189009056634

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

ISSN:0883-0185    

DOI:10.3109/08830189009056635

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

ISSN:0883-0185    

DOI:10.3109/08830189009056636

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

ISSN:0883-0185    

DOI:10.3109/08830189009056631

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor