Splenectomy and Impaired Resistance to Pneumococcal Infection

Abstract

Efforts to devise an animal model in which splenectomy decreases the effectiveness ofhost defences against acute bacterial infection have been infrequently successful. It has been difficult to provide a challenge which sharply differentiates controls from the operated animals. A model is described in which all splenectomized rats died after intravenous (i.v.) challenge with an LD₅₀ dose of pneumococcus Type 25. Normal rats immunized with pneumococcus Type 25 formalized bacteria and then challenged i.v. 3 to 6 days afterwards, all survived, while previously splenectomized rats, similarly immunized, all died. As the interval between immunizations and subsequent splenectomy was lenghtened in a stepwise fashion, the mortality following i.v. challenge fell from 80% to zero. Clearance of pneumococci from the blood stream reflected these results, more prompt disappearance of bacteria becoming evident at 1 to 3 hours after i.v. challenge in those most likely to survive. During this period of increasing antibacterial resistance both early antibody and the unique ability of the spleen to clear minimally opsonized bacteria were critical for effectiv antibacterial host defence. Early but delayed antibody could be detected in the immunized splenectomized rat, but was not adequate for protection in the absence of the spleen.

Log in or create a free account to read this content

Gain free access to this article, as well as selected content from this journal and more on nature.com

Access through your institution

or

Sign in or create an account

Continue with Google

Continue with ORCiD