Endotoxin desensitization of human mononuclear cells after cardiopulmonary bypass: role of humoral factors.
BACKGROUND
The ability of leukocytes to release proinflammatory cytokines on lipopolysaccharide stimulation in vitro is impaired after cardiopulmonary bypass (CPB). This study tested contribution and interaction of humoral factors in altered leukocyte responsiveness to lipopolysaccharide.


METHODS
Whole blood and isolated peripheral-blood mononuclear cells (PBMCs) from 10 patients obtained after induction of anesthesia (T1) and 20 min (T2) and 24 h (T3) after CPB were cultured in the absence or presence of lipopolysaccharide and assessed for release of tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-1beta and their functional antagonists, IL-1 receptor antagonist (IL-1ra) and IL-10. In addition, dose-response characteristics and interaction of IL-10 and norepinephrine as modulators of TNF-alpha release were studied.


RESULTS
Cardiopulmonary bypass induced release of antiinflammatory (T2: IL-10: median 25 pg/ml, 25th-75th percentile 9-42; IL-1ra: median 1,528 pg/ml, 25th-75th percentile 1,075-17,047; P < 0.05 compared with T1) but failed to induce proinflammatory cytokines (T2: TNF-alpha: median 0 pg/ml, 25th-75th percentile 0-6; IL-1beta: median 1 pg/ml, 25th-75th percentile 0-81; nonsignificant). Removal of plasma at T2 increased TNF-alpha response to lipopolysaccharide (+83.8%; P < 0.05), whereas it suppressed IL-10 (-36.8%; P < 0.05). Similarly, incubation of PBMCs (T1) with plasma obtained after CPB (T2) as well as addition of IL-10 or norepinephrine in concentrations present in plasma after CPB led to a reduced lipopolysaccharide-stimulated TNF-alpha and an increased IL-10 response. Coadministration of norepinephrine and IL-10 had synergistic effects. Although pretreatment with an anti-IL-10 antibody and labetalol before addition of plasma obtained at T2 largely restored the TNF-alpha response in vitro, their addition post-treatment failed to restore the monocytic TNF-alpha response.


CONCLUSIONS
Plasma contains interacting factors that inhibit the release of TNF-alpha and increase the release of IL-10, presumably attenuating the inflammatory response to CPB. Although norepinephrine fails to induce a cytokine response in the absence of other stimuli, its administration seems to augment the antiinflammatory IL-10 response while attenuating the TNF-alpha response.
Department of Anesthesiology and Critical Care Medicine, University of Saarland, Homburg, Germany.
U
U
Grundmann
H
H
Rensing
H A
HA
Adams
S
S
Falk
O
O
Wendler
N
N
Ebinger
M
M
Bauer
D000328:Adult; D000368:Aged; D000917:Antibody Formation / Q000187:drug effects*; D002395:Catecholamines / Q000097:blood; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D001026:Coronary Artery Bypass; D016207:Cytokines / Q000096:biosynthesis* / Q000187:drug effects / Q000378:metabolism; D003888:Desensitization, Immunologic; D004731:Endotoxins / Q000276:immunology / Q000494:pharmacology*; D006801:Humans; D007958:Leukocyte Count; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D013312:Stress, Physiological
D002395:Catecholamines; D016207:Cytokines; D004731:Endotoxins