Antibody-dependent cellular cytotoxicity to allogeneic but not autologous erythroblasts in vitro

Antibody-dependent cellular cytotoxicity (ADCC) is a very sensitive mechanism for immune injury of target cells, which utilizes extremely low concentrations of antibody. We have developed a method for demonstrating this type of cytotoxicity to normal human erythroblasts. The latter were enriched 3- to 4-fold and were then labeled with 59Fe. Blood lymphocytes from the same donor were enriched to 93% and were added as effector cells at a 60:1 ratio to the target cells. After 4 hr at 37 degrees C, as 5- to 10-fold increase in the release of 59Fe occurred when the plasma or IgG from patients with pure red-cell aplasia was present. This activity was not present when the effector cells were absent. However, this activity was found in the remission plasmas of patients and was not found when autologous erythroblasts were used. These studies demonstrate a method for detecting ADCC to allogeneic normal human erythroblasts. This ADCC does not appear to be related to the disease since a similar autoimmune activity to the patients' own erythroid cells was not detected. Further studies are suggested using other effector cells in this system.