Effect of hyperbaric oxygen on murine neutrophil and T-lymphocyte functions

We investigated the effect of repeated hyperbaric oxygen (HBO) exposure on PMN and T-lymphocyte functions in a murine model. Animals received eight 90-min exposures twice daily to 2.4 ata and 100% or 10% oxygen. Control animals were maintained in room air. On the ninth day spleens and peritoneal cell exudates were harvested. Phagocytosis was measured by flowcytometric analysis of the ability of PMN to engulf formalin-killed, fluorescence-labeled Staphylococcus aureus. PMN-killing capacity was measured by the ability of PMN to undergo an oxidative burst after stimulation with N-formyl methionyl-leucyl-phenylalanine, phorbol myristate, or opsonized zymosan. T-lymphocyte subpopulations were identified using monoclonal antibodies and two-color flow cytometry after 48 h stimulation with phytohemagglutinin, and lymphocyte proliferation was measured by 3 H-thymidine incorporation. We found PMN phagocytosis and oxidative burst were unchanged after HBO treatment. Lymphocyte proliferation was decreased, and an activated population of CD8+ T cells appeared after mitogen stimulation. We conclude that, although PMN function is not affected by prior HBO, lymphocyte proliferation is decreased. (Crit Care Med 1990; 18:974)