CD95 is not functional in human erythrocytes

Introduction: The CD95 pathway is a potent inducer of apoptosis in nucleated cells and this death receptor is important for proper blood cell development. Although it is expressed in red blood cells, its functional role in erythrocytes is not well documented. These anucleated cells can undergo cell death via eryptosis, a process showing similarities to apoptosis of nucleated cells. This mode of cell death is mainly triggered by oxidative stress or energy depletion. Methods: CH11 was added to the purified human erythrocytes for induction of phosphatidylserine (PS) exposure. AnnexinV-FITC was used as a probe for PS detection. Results: No significantly enhanced PS-positive cell fraction could be observed after erythrocytes were treated with CH11. Conclusion: Based on some key features for an activated CD95 system, this death receptor has been considered to induce PS exposure. However, we give evidence, that CD95 is not functional in red blood cells and that activation of this death receptor does not lead to the exposure of phosphatidylserine.