Studies on the Immune Response of Guinea Pigs to the Envelope Substance of Pasteurella Pestis

According to fluorescent antibody observations, Fraction I injected in oil persisted in guinea pigs for 186 to 210 days. Its distribution detected with fluorescent antibody and by radioactivity differed. The latter suggested combination with antibody resulting in catabolism by the liver, elimination by the kidneys and brief storage in bone marrow not seen with fluorescent antibody. Only fixed reticular macrophages and fibroblasts were observed to ingest the antigen. It was not stored long in these cells. Many vessels, sinuses and other microscopic cavities were lined with a thick coating of the antigen. The last appearance in antibody producing centers was in the germinal centers of Flemming. Partial immunity developed 3 months after primary injection and could be restimulated at 6 months. Immunounresponsiveness of guinea pigs to Fraction I in oil was temporary; eventually a partial immunity arose.