title: Absence of peripheral blood mononuclear cells priming in hemodialysis patients.
abstract: As a consequence of the proinflammatory environment occurring in dialytic patients, cytokine overproduction has been implicated in hemodialysis co-morbidity. However, there are discrepancies among the various studies that have analyzed TNF-alpha synthesis and the presence of peripheral blood mononuclear cell (PBMC) priming in this clinical setting. We measured bioactive cytokine by the L929 cell bioassay, and evaluated PBMC TNF-alpha production by 32 hemodialysis patients (HP) and 51 controls. No difference in TNF-alpha secretion was observed between controls and HP (859 +/- 141 vs 697 +/- 130 U/10(6) cells). Lipopolysaccharide (5 microg/ml) did not induce any further TNF-alpha release, showing no PBMC priming. Paraformaldehyde-fixed HP PBMC were not cytotoxic to L929 cells, suggesting the absence of membrane-anchored TNF-alpha. Cycloheximide inhibited PBMC cytotoxicity in HP and controls, indicating lack of a PBMC TNF-alpha pool, and dependence on de novo cytokine synthesis. Actinomycin D reduced TNF-alpha production in HP, but had no effect on controls. Therefore, our data imply that TNF-a production is an intrinsic activity of normal PBMC and is not altered in HP. Moreover, TNF-alpha is a product of de novo synthesis by PBMC and is not constitutively expressed on HP cell membranes. The effect of actinomycin D suggests a putative tighter control of TNF-alpha mRNA turnover in HP. This increased dependence on TNF-alpha RNA transcription in HP may reflect an adaptive response to hemodialysis stimuli.
authors.affiliation: Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brasil. bsantos@nefro.epm.br
authors.forename: B C
authors.initials: BC
authors.lastname: Santos
authors.forename: N
authors.initials: N
authors.lastname: Starobinas
authors.forename: J A M
authors.initials: JA
authors.lastname: Barbuto
authors.forename: M
authors.initials: M
authors.lastname: Russo
authors.forename: N
authors.initials: N
authors.lastname: Schor
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003513:Cycloheximide / Q000494:pharmacology; D016207:Cytokines / Q000096:biosynthesis*; D003609:Dactinomycin / Q000494:pharmacology; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D006435:Renal Dialysis; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
chemical_list: D016207:Cytokines; D011500:Protein Synthesis Inhibitors; D014409:Tumor Necrosis Factor-alpha; D003609:Dactinomycin; D003513:Cycloheximide