Cellular and humorial immune responses in mice. III. Acceleration of delayed hypersensitivity response by presensitization with suboptimal dose of antigen.

Delayed hypersensitivity (DH) response in mice induced by subcutaneous (s.c.) injection of optimal dose of sheep red blood cells (SRBC) 10(8)) was accelerated by s.c. injection of the antigen of 10(3) or more doses, given 2 or more days earlier. The accelerated response appeared soon after the injection of optimal antigen dose, that is, 1 or 2 days earlier than the response of non-presensitized control. The acceleration was antigen specific. The accelerated response was generally accompanied by an acceleration and/or enhancement of humoral antibody response. Parallel to the acceleration of DH response, the proliferation of regional lymph node cells in the presensitized mice was induced immediately after the following injection of 10(8) SRBC, 1 day earlier than that of non-presensitized animals. These results suggest that presensitization of mice with the antigen induces DH-related memory cells which proliferate immediately after the following injection and function as effector cells for DH reactions, and that the development of DH-related memory cells occurs in close relation to that of helper thymus-derived (T) cells for antibody production.