The interaction of human peripheral blood eosinophils with bacterial lipopolysaccharide is CD14 dependent.
Bacterial lipopolysaccharide (LPS, endotoxin) is a ubiquitous component of dust and air pollution and is suspected to contribute after inhalation to an activation of eosinophils in bronchial tissues of asthmatic patients, provoking inflammatory and allergic processes. We were therefore interested in the interaction of eosinophil granulocytes with LPS and have examined the activation of and uptake to human peripheral blood eosinophils by LPS. Eosinophils were stimulated by LPS and the endotoxic component lipid A and the release of tumor necrosis factor alpha (TNF-alpha) and of the eosinophil-specific granule protein eosinophil cationic protein (ECP) was estimated. The results show induction of TNF-alpha and ECP-release by LPS and lipid A in a dose-dependent manner. Anti-CD14 monoclonal antibody (moAb) (clone MEM-18) and the synthetic lipid A partial structure 406 blocked the release of TNF-alpha and ECP by LPS-stimulated eosinophils. Studies with radioactively labeled LPS showed dose-dependent uptake of (3)H-LPS to eosinophils. The (3)H-LPS uptake was found to be specific because preincubation with unlabeled LPS, compound 406 and also anti-CD14 antibodies inhibited uptake of (3)H-LPS to eosinophil granulocytes. By flow cytometry using anti-CD14 moAb and by reverse transcriptase-polymerase chain reaction (RT-PCR) technique, CD14 expression was detectable. Furthermore, messenger RNA (mRNA) expression of Toll-like receptors (TLR) 2 and TLR 4 was detected, indicating the presence of these CD14 coreceptors. The results indicate that eosinophils can take up LPS and can be stimulated by LPS in a CD14-dependent manner. Hence, in addition to allergens, eosinophils interact with endotoxin, a process that possibly exacerbates ongoing inflammatory and allergic processes.
Plötz
S G
SG
Department of Immunology and Cell Biology and the Department of Immunochemistry and Biochemical Microbiology, Research Center Borstel, Center for Medicine and Biosciences, Borstel, Germany.
Lentschat
A
A
Behrendt
H
H
Plötz
W
W
Hamann
L
L
Ring
J
J
Rietschel
E T
ET
Flad
H D
HD
Ulmer
A J
AJ
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001798:Blood Proteins / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism; D016207:Cytokines / Q000096:biosynthesis / Q000187:drug effects; D029721:Drosophila Proteins; D047091:Eosinophil Granule Proteins; D004804:Eosinophils / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008050:Lipid A / Q000494:pharmacology; D018950:Lipopolysaccharide Receptors / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000378:metabolism* / Q000493:pharmacokinetics; D008562:Membrane Glycoproteins / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D012260:Ribonucleases; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014316:Tritium; D014409:Tumor Necrosis Factor-alpha / Q000187:drug effects / Q000378:metabolism
D000911:Antibodies, Monoclonal; D001798:Blood Proteins; D016207:Cytokines; D029721:Drosophila Proteins; D047091:Eosinophil Granule Proteins; D008050:Lipid A; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha; D014316:Tritium; D012260:Ribonucleases