BACTERIAL KILLING BY NEUTROPHILS IN HYPERTONIC ENVIRONMENTS

The effects of hypertonic sodium chloride and urea solutions on the ph agocytosis and killing of Escherichia coli by neutrophils were examine d. Neutrophil function was progressively inhibited by increasing osmol arity, with sodium chloride more inhibitory than urea. However, neutro phils killed at 25% of normal rates in 500 mosmol/L NaCl, and in 300 m osmol/L NaCl with 800 mosmol/L urea. These concentrations would rarely be exceeded in the human urinary tract. Inhibition of neutrophil supe roxide production and degranulation was similar to that observed with phagocytosis and killing, Neutrophils also phagocytosed and killed E. coli in isotonic and hypertonic urine, but no improvement in function attributable to the uptake of urinary osmoprotectants was evident. It is concluded that physiologic levels of sodium chloride and urea will slow, but not prevent, neutrophil activity at a hypertonic site of inf ection.