EFFECT OF HYPEROXIA ON MIGRATION OF ALVEOLAR MACROPHAGES INVITRO

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Abstract
Apparently directed migration (chemotaxis) is involved in the recruitment of alveolar macrophages in vivo. Because O2 is widely used in the treatment of pulmonary diseases, the effect of hyperoxia was examined on migration of guinea pig alveolar macrophages in vitro. Migration was measured in blind well chambers incubated in either room air or hyperoxia. N-formyl-methionyl-phenylalanine was used to stimulate random migration and to produce directed migration. Migration was quantified by counting the number of mononuclear cells per oil immersion field that migrated completely through a polycarbonate filter with 5 .mu.m pores. The average PO2 [O2 partial pressure] in the cell suspensions incubated in room air was 100 mm Hg. In the hyperoxic environments the average PO2 at 1 h was 260 mm Hg; at 2 and 3 h it was 410 and 425 mm Hg, respectively. In 6 separate experiments there was no significant difference between the mean response to N-formyl-methionyl phenylalanine in hyperoxia and in room air after 1 h of incubation. After 2 and 3 h of incubation the response in hyperoxia was significantly P < 0.002) lower than that in room air. The decreased response in hyperoxia did not appear to result from loss of viability of responding cells, diminished adherence of cells to the filters, loss of activity of N-formyl-methionyl phenylalanine exposed to high PO2 or failure of the cells the exhibit directed migration. Apparently hyperoxia decreased the response of alveolar macrophages primarily by impairing random migration.