Distribution of cells mediating delayed type hypersensitivity responses of mice to sheep red blood cells.

Jones-Mote type delayed hypersensitivity (DTH) was elicited in mice by intravenous (i.v.) or subcutaneous (s.c.) injection of sheep red blood cells (SRBC) in saline. The state of DTH was measured by means of a footpad swelling test. Splenectomy at different intervals after i.v. immunization with 3 X 10(5) SRBC abolished the generalized state of DTH almost completely, even when splenectomy was performed as late as 6 days after immunization. Excision of the popliteal lymph node on the fifth day after s.c. immunization with 3 X 10(6) SRBC prevented footpad swelling after administration of a challenge dose of SRBC. These experiments suggest that Jones-Mote type DTH responsiveness to SRBC remains dependent on the presence of the initially reactive lymphoid organ, provided the dose of antigen is too low to evoke the generation of DTH-reactive cells in other lymphoid organs.