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2001 Abstract: 2401 In Vitro Production of Hydrogen Peroxide by Human Monocytes Obtained from Jaundice Patients

2001 Digestive Disease Week

# 2401 In Vitro Production of Hydrogen Peroxide by Human Monocytes Obtained from Jaundice Patients
Marisa Treglia-Dal-Lago, José Jukemura, Marcel C. C. Machado,

José A. M. Barbuto, São Paulo, Brazil

BACKGROUND: Jaundice causes several alterations of immune function in humans. Most studies have concentrated their attention on neutrophil and lymphocyte functions. In this study we analyzed monocyte function, as measured by the spontaneous and phorbol myristate acetate (PMA) -induced production of hydrogen peroxide, in jaundice patients.

METHODS: Peripheral blood was obtained from jaundice patients treated at the "Divisão de Cirurgia de Vias Biliares do HC FMUSP", before treatment and 1 to 2 weeks after surgery, with relief of cholestasis. Bilirrubin levels were measured at the time of all blood collections. Mononuclear cells (PMBC) were separated by density gradient centrifugation over Ficoll-paque and cultured for 1 hour in peroxidase and phenol red containing medium, in the presence, or not, of phorbol myristate acetate (PMA-30ng/ml), Hydrogen peroxidase release was evaluated by phenol oxidation, as measured by absorbance at 620 nm in an ELISA reader.

RESULTS: PMBC obtained from patients before surgery did not release any hydrogen peroxide, neither spontaneously, nor with PMA stimulation. After relief of cholestasis, PMBC from 7/10 patients acquired the ability to release hydrogen peroxide with PMA stimulation. In these cases, the level of hydrogen peroxide produced varied between 0.5 to 1.0 nmoles/well. Also PMBC obtained before surgery, but maintained "in vitro" for 1 week, produced hydrogen peroxide when stimulated with PMA (in 8/10 patient).

CONCLUSION: These results indicated that monocyte from jaundice patients shows a deficit in their hydrogen peroxide production, that can be reversed when bilirrubin levels decrease, both "in vivo" and "in vitro" (after culture).

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