A new therapeutic antibody removal method using antigen positive red cells. Application to M-incompatible pregnant...

A study was made for the therapeutic removal of red cell antibodies using antigen positive red cells. With preliminary experiments in vitro, the criteria for the optimal absorption of anti-M with O MM red cells were estimated to be the following: an incubation time of 10 min, an incubation temperature of 0-4 degree C (in an ice-water bath), and a red cell-to-plasma ratio of 1:2.5. On the basis of these in vitro experiments, the following procedure was designed. One unit (about 90 ml) of O MM packed red cells was added to a bag containing 250 ml of patient's plasma, the mixture was incubated in an ice-water bath for 10 min. Following centrifugation, autologous plasma from which the antibodies were removed was reinfused. After absorption the titer of anti-M fell from 512 to 4. No variation in the level of other plasma components was detected and no hemolysis was seen. After 2.51 of patient's plasma was treated using the above described method, the antibody titer usually decreased one log2 unit. When this method was compared with exchange plasmapheresis, no significant abnormalities in the immunoglobulin and hemostatic factors could be detected, but a moderate decrease in platelet count was seen after plasmapheresis. Thus, it appears that our method provides a rational therapeutic modality for specifically removing antibodies.