Effect of omeprazole, lansoprazole, and ranitidine on the DNA synthesis of mononuclear cells.

Abstract

To examine and compare the effects of omeprazole, lansoprazole, and ranitidine on the DNA synthesis of peripheral blood mononuclear cells. Ex vivo laboratory study. Clinical research laboratory of an academic medical center. Healthy volunteers. None. Venous blood was collected from normal subjects and peripheral blood mononuclear cells (PBMCs) were isolated using centrifugation techniques over a Ficoll-Hypaque density gradient. PBMCs were added to 12-well culture plates in four groups of media: a) control; b) control plus lansoprazole (25 microg/mL); c) control plus omeprazole (0.35 microg/mL); and d) control plus ranitidine (50 microg/mL). PBMCs were exposed to the drug for 96 hrs, with addition of phytohemagglutinin (2.5 microg/ mL) for the last 48 hrs, and 3H-thymidine (1 microCi) during the final 6 hrs. PBMCs were filtered onto glass-fiber filter paper and the radioactivity was determined by scintillation counting. Since radioactivity is measured only in those cells undergoing DNA synthesis or cell division, results are expressed as quantification of 3H-thymidine uptake. Median disintegrations per min (DPM)/number of PBMCs per well+/-SEM are reported: control 68.3+/-37.8; ranitidine 38.4 +/-94.2; lansoprazole 14.6+/-84.4; and omeprazole 15.1+/-48.9. There was a significant difference between lansoprazole vs. ranitidine (p< .01), and omeprazole vs. ranitidine (p< .05), and no significant difference between lansoprazole and omeprazole. This is the first study to compare the potential immunomodulating effects of these commonly used agents. Ranitidine caused increased DNA synthesis in PBMCs when compared with lansoprazole and omeprazole. This phenomenon may be an important, often disregarded, effect of histamine-2-receptor antagonists when used in postsurgical or trauma patients who have T-lymphocyte-mediated immune suppression.