Immune response against hamster erythrocytes in the low-responder mouse strains. VII. Competitive suppression of antibody production against hamster erythrocytes by the simultaneous development of a delayed hypersensitivity against the antigen

1) A subcutaneous injection of hamster erythrocytes (HRBC) in Freund's complete adjuvant (FCA) or an intravenous injection of hamster lymph node (HLN) cells suppressed antibody production against HRBC in the low‐responder C57BL/6 and AKR mice, when HRBC in saline were given on the same day; 2) The suppressing effect of such treatments was neither detectable in the high‐responder SL mice, nor in the C57BL/6 mice, which had been pre‐sensitized with HRBC in FCA or hamster lymphoma cells; 3) Positive reactions of the peritoneal macrophage disappearance test and the enhanced antibody production were detected seven days after treatment with HRBC in FCA and HRBC in saline, or HLN cells and HRBC in saline; 4) The suppressing effect of such simultaneous treatments on anti‐HRBC antibody production was eliminated by a transfer of normal syngeneic thymus cells to AKR mice or a transfer of thymus cells from SL to C57BL/6 mice. Suppression of the antibody production in the low‐responder mice by the described simultaneous treatments may be due to a competitive involvement of HRBC‐specific thymus‐derived cells (T cells) in the developmental stages of delayed hypersensitivity and antibody production. High‐responder SL mice appear to have enough T cells for development of the delayed hypersensitivity and as helper cells in antibody production. These results appear to support the concept that T cells for delayed hypersensitivity and antibody production to HRBC antigen are derived from the same original pool.