The in vitro effects of heparin, dipyridamole (DIPY) and lysine-acetylsalicylate (LASA) on human peripheral blood leucocyte migration and upon production/release and effect of leucocyte migration inhibitory activity (LMIA) from lymphocytes stimulated with concanavalin-A (con-A) have been studied. The final concentration of each drug was of the same order of magnitude as during clinical treatment. The leucocyte migration under agarose was significantly increased by DIPY at a concentration of 100 mug/ml. The release/production of LMIA was inhibited by DIPY at 1 mug/ml and by LASA at 0.3 mug/ml. Heparin had no influence on LMIA release, even at 10 IU/ml. The LMIA of supernatants from con-A-stimulated lymphocyte cultures was inhibited by DIPY at a concentration of 10 mug/ml, by LASA at 3 mug/ml and by heparin at 10 IU/ml. The findings suggest that DIPY and LASA could have a dual role as modifiers of inflammation: 1) the well known role as antiaggregants tending to limit and impede thrombosis, and 2) as antagonists to the lymphocyte-mediated (type IV) immune reaction through a depressive action on lymphokine production/release and activity.
