Renal tubular absorption of β2 microglobulin

Renal tubular absorption of β2 microglobulin. 125Iodinated human β2 microglobulin (β2m, 5 to 30 mg) was administered to anesthetized rats. Clearance studies showed a low threshold of excretion of injected β2m and a high Tm of 400 to 600 µg · min-1 · kg-1. A glomerular sieving coefficient of 0.97 was calculated as the slope of the curve: β2m excretion rate = F (plasma β2m × glomerular filtration rate) for values above saturation. Electrophoresis analysis of proteinuria in agarose gel and sodium dodecyl sulfate polyacrylamide gel showed that injection of saturating doses of β2m induced the excretion of proteins of similar size but different charge and that of other proteins of different size. Among the latter, some were excreted transiently in association with β2m, whereas others had a delayed excretion suggesting existence of a complex mechanism of reabsorption whose steps remain to be elucidated.Absorption tubulaire rénale de la β2 microglobuline. De 5 à30 mg de β2 microglobuline (β2m) humaine marquée à l'Iode 125 ont été injectés à des rats anesthésiés. Des études de clairance ont montré un seuil d'excrétion bas et un Tm élevé de 400 à 600 µg · min-1 · kg-1. Un coefficient de tamisage de 0,97 a été mesuré à partir de la pente de la courbe: excretion de β2m = F (concentration plasmatique de β2m × filtration glomérulaire) pour les points au-dessus de la saturation. L'analyse de la protéinurie par électrophorèse sur gel d'agarose et sur gel de polyacrylamide avec dodecyl-sulfate de sodium a montré que l'injection de doses saturantes de β2m provoque l'excretion de protéines de même taille mais de charge différente, ainsi que de protéines de taille différente. Parmi ces dernières, certaines sont excrétées de manière transitoire et en même temps que la β2m, tandis que d'autres ont une excrétion retardée suggérant l'existence d'un mécanisme de réabsorption complexe dont les étapes restent à étudier

CONTROLE DE LA DELETION DES LYMPHOCYTES T APRES INJECTION D'UN SUPERANTIGENE BACTERIEN (EFFET DES ANTIMETABOLITES ET ROLE DES MOLECULES DE CLASSE I DU CMH)

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Alteration of deacylated lipopolysaccharide antagonistic properties by interaction with plasma factors

International audienceThe acyl poly(1,3)galactoside (APG) from Klebsiella pneumoniae is a bis-acylated Lipopolysaccharide(LPS) devoid of eater-linked fatty acids, APG interacts with CD14 and CD11b/CD18 on monocytes, This study addressed the role of serum proteins in the binding and functional properties of APG as a candidate LPS antagonist, In the absence of serum, APG did not induce tumor necrosis factor alpha (TNF-alpha) synthesis by human mononuclear cells and dose-dependently inhibited their activation induced by different LPS, Conversely, in the presence of 5% autologous plasma, APG activated cells and did not antagonize LPS, Serum decreased APG but not LPS binding to monocytes, Binding competition experiments indicated that APG and LPS competed for the same receptors in serum-free conditions but bound to different receptors in the presence of plasma, The data indicate that serum-dependent LPS receptors do contribute to LPS activation of monocytes but do hot recognize deacylated LPS analogues

Tumor necrosis factor-α up-regulates Bcl-2 expression and decreases calcium-dependent apoptosis in human B cell lines

International audienc

Binding to leukocytes and induction of TNFα production involve different sites within the lipid-A region of LPS-like molecules

International audienc

Apoptosis without decrease of cell DNA content

International audienc

Acylation of the lipid a region of a Klebsiella pneumoniae LPS controls the alternative pathway activation of human complement

International audienc