The removal of blood from normal dogs followed by the intravenous injection of human syphilitic serum in amounts varying from 30 to 50 cc. per kilogram of body weight was followed by the presence of small amounts of syphilis reagin (the antibody concerned in the Wassermann reaction) in the cerebrospinal fluid.
The reagin was found in the cerebrospinal fluid as early as three hours after transfusion with syphilitic serum; tests at shorter intervals were not made. The amount of reagin found in 0.5 cc. of cerebrospinal fluid was small in all experiments as based upon the degree of complement fixation with all antigens.
After irritation of the spinal meninges by the preliminary injection of sterile horse serum the amount of reagin gaining access to the cerebrospinal fluid after transfusion of syphilitic serum, appeared to be somewhat greater.
All traces of syphilis reagin in the cerebrospinal fluid of dogs following transfusion of human syphilitic serum apparently disappeared after 22 to 48 hours as determined by completely negative Wassermann reactions.
The intravenous injection of dog-typhoid immune serum into a normal dog in amount of about 30 cc. per kilogram of body weight, was followed by the appearance of traces of agglutinin in the cerebrospinal fluid within three hours after transfusion; fluid removed forty-eight hours later was free of agglutinin.
These experiments demonstrate the possibility of the passage of antibody from the blood into the cerebrospinal fluid without primary involvement of the central nervous organs or injury to the mechanism concerned in the production of cerebrospinal fluid, when the amount of antibody in the blood has reached a point of high concentration. While it is possible that in human syphilis the presence of traces of reagin in the cerebrospinal fluid may be due to the passive transfer of this substance from the blood, as shown by Wile and Stokes the presence of the reagin with or without other changes in the fluid, as an increase of protein and cells usually indicates the presence and activity of T. pallida in the tissues of the central nervous organs.