Objective: To study the in vitro effects of low-molecular weight heparin (LMWH) and dexamethasone on the hemolysis of red blood cells from paroxysmal nocturnal hemoglobinuria (PNH) patients.
Methods: By Ham's test and micro-complement lysis sensitive test (mCLST), the changes of hemolysis of red blood cells from 6 PNH patients were tested by adding different doses of LMWH and dexamethasone into the test mixture. The effects of LMWH and dexamethasone on the coagulation of the tested blood samples were also studied by activated partial thromboplastin time (APTT).
Results: (1) Either LMWH or dexamethasone could dose-dependently inhibit the hemolysis of PNH red blood cells, and the effects were synergistic when added together. The same dose of LMWH induced a less than 100% prolongation of APTT. (2) Dexamethasone could inhibit the hemolysis in Ham's test and had different effects on the hemolysis by different adding methods in mCLST. LMWH could inhibit the hemolysis in both Ham's test and mCLST.
Conclusion: Both LMWH and dexamethasone could inhibit the hemolysis of PNH red cells and showed a synergistic effect. The mechanisms of the inhibition of hemolysis were different. Furthermore, a tolerable dose of LMWH induced only a limited prolongation of APTT, which might be useful for controlling acute hemolysis and reducing the dose of dexamethasone.