THE EFFECT OF OMEPRAZOLE ON HUMAN NATURAL-KILLER-CELL ACTIVITY

1. Omeprazole, an antiulcer drug, inhibits the gastric acid pump via b locking the parietal cell (H++K+)-ATPase. Omeprazole was also reported to have an inhibitory action on polymorphonuclear neutrophil activiti es. In the present study the potential effect of omeprazole on human n atural killer cell (NK) activity was investigated. 2. Omeprazole decre ased NK cytotoxic activity in a dose-dependent manner. 3. Degraded ome prazole showed a similar action. 4. In vitro NK inhibitory action of o meprazole and its acid-degraded form was observed at the concentration s equal and higher than 18 mu M (micromolar). 5. NK inhibitory action of omeprazole was recovered to 75% by washing away of the agent. 6. Om eprazole decreased the conjugate formation of effector and target cell s by 50% at the concentration of 288 mu M.