Immunologic Response to Subarachnoid and Intracerebral Injection of Antigens

Summary Antibody response in rabbits was measured after canine red blood cells (RBC) and Brucella antigen were injected s.c., i.v., into the cisterna magna (i.c.m.), and into the substance of the brain (i.c.). The following average agglutinin titers were observed after injection of RBC: s.c., 1:320; i.v., 1:5,120; i.c.m., 1:30,000; and i.c., 1:160. The following average hemolysin titers were observed after injection of RBC: s.c., 1:10; i.v., 1:16; i.c.m., 1:28; i.c., 1:8. After injection of Brucella antigen, agglutinin titers were s.c., 1:200; i.v., 1:900; and i.c.m., 1:2,560. In splenectomized rabbits agglutinin and hemolysin titers after s.c. injection were similar to titers after s.c. injection in normal rabbits. After i.v. injections in splenectomized rabbits, titers were similar to those attained after s.c. injection. Titers after i.c.m. injection in splenectomized rabbits were similarly lower than titers produced by i.c.m. injection in normal rabbits. Magnitude of the antibody response was thought to be related to the distribution of antigen in the body; the extremely high titers after i.c.m. injection, to a “slow leak” of antigen from the cerebrospinal fluid into the blood.