The deleterious effect of reduced pH and hypoxia on neutrophil migration in vitro

The effect of altered microenvironment on human neutrophil locomotion was investigated. Reduced pH impaired both random and chemotactic migration using both the under-agarose and Boyden chamber techniques. Using the under-agarose technique, migration was progressively inhibited below pH 6.5, achieving significance at pH 5.5 (P less than 0.01 vs pH 7.5 for chemotactic and random migration). A similar pattern was noted using the Boyden chamber technique. At pH 7.40, extreme hypoxia (less than 30 mm Hg) caused a small (15-25%) but significant reduction in chemotactic migration. An additive deleterious effect of low pH and hypoxia on PMN migration was also found. These studies suggest that altered local microenvironment may contribute to the failure of host leukocytes to resolve infection.