Experimental autoimmune anemia induced with haptenated syngeneic mouse red blood cells and low dose X-irradiation

This paper describes an experimental model of autoimmune anemia induced with haptenated syngeneic mouse red blood cells (MRBC). A strain mice immunized with penicillinated MRBC (PEN-MRBC) generated IgM anti-MRBC autoantibody response and a very low level of the corresponding IgG response. The IgG anti-MRBC autoantibody response was augmented when mice were X-irradiated (250 rad) prior to immunization with PEN-MRBC, suggesting that a radiosensitive suppressive mechanism controls the IgG autoantibody response. Both the IgM and the IgG secondary anti-MRBC autoantibody responses emerged in mice that had been injected with PEN-MRBC 2 months before a second PEN-MRBC injection. Low dose X-irradiation (250 rad) of A mice without subsequent immunization induced an early IgG anti-MRBC autoantibody response and late IgM response, suggesting the existence of antierythrocyte autoreactivity in normal animals which is controlled by a radiosensitive suppressor mechanism. The anti-MRBC autoantibody response was not only induced by PEN-MRBC. Multiple injections of A mice with trinitrophenylated MRBC also induced autoantibodies against erythrocytes. The IgG anti-MRBC autoantibody response was associated with anemia, but it is not yet known if the two events are related or independent. Autoantibodies of X-irradiated mice immunized with PEN-MRBC were linearly titrated and partially absorbed with MRBC. Less efficient absorption was achieved with human and sheep red blood cells. Fifty percent of splenocytes from X-irradiated mice injected with PEN-MRBC expressed IL-2 receptor 3 days after the injection, whereas the number of cells expressing this receptor earlier or later was significantly less. The various applications of this autoimmune model are discussed.