Results of experimental studies on mice concerning the important role of cells producing normal autoantibodies (AAPC) in the reaction of the organism to specific antigens have been systematized. The number of AAPC in the blood and organs increases as early as 15-20 min after the administration of antigen and this increase is particularly intensive during reimmunization. On the other hand, the administration of heterologous antigens to the same mice causes a decrease in the number of AAPC. Transfer of blood plasma from immunized donors induces an increase in the number of AAPC in the recipients. The addition of specific antigen to blood preparations conditions a considerable increase in the number and size of AAPC in immunized humans and animals. It has been demonstrated that one and the same cell produces both auto-antibodies and specific hemolysins. A hypothesis has been proposed dealing with the stages of involvement of autoantibody-producing cells in the immune response and with a new type of intercellular interactions between erythrocytes and karyocytes.