Differential Effect of Heterologous Anti-Lymphocyte Serum on Antibody-Producing Cells and Antigen-Sensitive Cells

Abstract

Summary Rabbit antiserum to mouse lymphocytes (anti-lymphocyte serum (ALS)) did not suppress the primary cellular 19 S or 7 S immune response to sheep red blood cells when given after the antigen. Furthermore, ALS failed to decrease the number of antibody-producing cells when injected into animals already hyperimmunized against sheep red blood cells, but had marked suppressing effect on the antigen-sensitive cells in these animals. This was investigated by a transfer system: hyperimmune spleen cells from ALS-treated and untreated donors, respectively, were mixed with sheep red blood cells and inoculated into irradiated (600 r) syngeneic, nonimmunized recipients. The number of 19 S and 7 S antibody-producing spleen cells was determined 7 days later. Transfer of spleen cells from ALS-untreated donors resulted in excessive cellular 7 S production, in the recipients. The total number of 7 S cells exceeded 106 per spleen and the proportion varied between 1 and 50% as a rule. Pretreatment of the immunized donors by ALS caused a reduction of more than 90% of the number and proportion of 7 S antibody-producing cells in the secondary hosts. Analogous results were obtained for 19 S production. The effect could not be ascribed to destruction of ALS-treated cells in the secondary recipients. The results suggest a differential effect of ALS on antibody-producing cells and antigen-sensitive cells.