Serotherapy with thymoglobulin and alemtuzumab differentially influences frequency and function of natural killer cells after allogeneic stem cell transplantation

Although thymoglobulin and alemtuzumab are frequently used in hematopoietic stem cell transplantation (HSCT), little is known of their effects on NK cells, which mediate important functions in post-transplantation immunology. In the present study, we determined NK cell death in vitro using propidium iodide and Annexin V. The NK cell activity in 34 patients at day +30 after allogeneic HSCT was assessed using the CD107a assay. Alemtuzumab and thymoglobulin were similarly very potent in inducing NK cell death in vitro. Even in low concentrations (1 microg/ml) the antibodies induced apoptosis and necrosis in a relevant percentage of NK cells (30%). However, the number of tumor reactive (CD107a+…