Conflicting data have been reported about the impact of repeated HBO2 exposure on the production of superoxide radicals during the neutrophil respiratory burst (RB) and on phagocytosis. In this study we wanted to see if exposure to hyperoxia would affect human neutrophil RB and phagocytosis. Short- and long-term effects after single or repetitive HBO2 exposure of 2.5 atmospheres absolute over a period of 90 min were studied in 40 healthy volunteers. The RB was measured by the intracellular oxidation of dihydrorhodamine after induction by Escherichia coli (E. coli), or priming with recombinant tumour necrosis factor alpha (TNF-alpha), followed by N-formyl-methionyl-leucyl-phenylalanine (fMLP) stimulation. The phagocytic activity was determined by the intake of FITC-labelled opsonized E. coli. No differences could be found between RB and phagocytic activity before and after HBO2 therapy, regardless of short- or long-term exposure. These findings indicate that exposure to hyperoxia does not impair these two important functions of the human innate host defense.

Ziel der Studie: Methodik: Ergebnisse: Schlussfolgerung: Objective: Methods: Results: Conclusions:

OBJECTIVE:Despite favourable clinical data on the successful use of hyperbaric oxygen (HBO), only limited investigations have been carried out to date regarding the influence of hyperoxia on leukocyte function. In a murine model, CD4+ T-cell population remained unchanged after repeated HBO exposure, however CD8+ cells were found to be increased. The aim of this study was to investigate whether repetitive exposure to hyperoxia would affect human monocyte and lymphocyte function.METHODS:Methods: After Ethics Committee approval the effects of elevated partial oxygen pressure were studied in the course of a ten-day HBO therapy (2.5 atmospheres absolute over a daily period of 90 min). Monocytes and lymphocytes of 30 patients with acute hearing loss were determined by flow cytometry before, throughout and after HBO therapy using monoclonal antibodies to CD3, CD4, CD8, CD14, CD25, CD45 and HLA-DR. Statistical analysis was made by ANOVA (analysis of variance).RESULTS:The relative percentage of CD3+, CD4+, CD8+, CD25+, CD14+, and HLA-DR+ cells remained unchanged during the course of and after HBO therapy.CONCLUSIONS:We conclude that repetitive exposure to hyperoxia does not influence human monocyte and lymphocyte functions in contrast to experimental data.