In acute and chronic experiments, each of eight groups of young mice were assigned separately to different pressures of oxygen to which it was to be exposed. Lymphocytes from spleen, thymus, and peripheral blood were analyzed following oxygen exposure. Subset populations changed depending on the oxygen tension. Blood lymphocyte populations reflected lymphocyte changes in thymus or spleen. Thus, a full understanding of the pharmacological effects of hyperbaric oxygen, requires a knowledge of simultaneous effects of increased oxygen pressures on the various compartments comprising the immune system.

Lee, Hester, Coggin, Gottlieb, , , , , (1993). Increased oxygen tensions modulate the cellular composition of the adaptive immune system in BALB/c mice. Cancer biotherapy, 1993 ;8(3):241-52. https://www.ncbi.nlm.nih.gov/pubmed/7804365