The Importance of Splenic Blood Flow In Clearing Pneumococcal Orgnanisms

Abstract

Overwhelming infection from encapsulated bacteria occurs after splenectomy. Decreases in IgM, tufsin, and serum opsonin are known to occur in animals and humans after splenectomy. A substantial immunologic advantage exists if some splenic tissue remains, but this may not offer sufficient protection from encapsulated bacteria if splenic arterial blood flow is reduced. This experiment was designed to examine the rate of pneumococcal clearance by the spleen and to determine the relationship between splenic blood flow and splenic tissue mass in bacterial clearance from the blood. Pneumococcal clearance, splenic blood flow, and residual splenic weight were measured in 171 rabbits with normal spleens, ligated splenic arteries, splenic autotransplants, hemisplenectomies, and splenectomies. Interruption of the splenic artery results in delayed pneumococcal clearance that is due to reduced blood flow and not to a decrease in splenic tissue mass. Splenic artery ligation to preserve an injured spleen cannot be assumed to give protection from sepsis.

Animal Models ofStreptococcus pneumoniaeDisease

“…Outbred strains, including Wistar, Sprague-Dawley, and CD (derived from Sprague-Dawley) rats, have been extensively utilized as experimental models (2,49,71,79,101,103,145,147,166,193,214,221,242,253). The New Zealand White rabbit is the most commonly used strain to induce pneumococcal pneumonia, sepsis, and meningitis (26,57,69,98,106,119,196,246). Finally, the chinchilla (only outbred strains are available), gerbil, and guinea pig are commonly used animal models of experimental otitis media (81,89,90,260).…”

“…route, and the model was employed to analyze the roles of lysosomes and cathepsin inhibitor in plasma (98), metabolic alterations in the course of disease (96), and the effects of splenectomy and drug therapy in the disease (97). An intracardiac model of experimental sepsis in New Zealand White rabbits was utilized to investigate the key role played by the spleen during the disease (106). This represents another example of refined surgery and measurements of clinical parameters in the rabbit in the course of infection.…”

Neural Signaling in the Spleen Controls B-Cell Responses to Blood-Borne Antigen

“…MZ and B1 B cells have a preactivated phenotype and express membrane immunoglobulins mainly of the immunoglobulin M (IgM) isotype (10); thus, they can initiate a rapid antibody response to bacterial polysaccharide which is detectable in the serum as early as 48 h after infection (8). These critical steps underlying B-cell activation and migration are key to efficient secretion of antibodies, which is necessary to confer significant protection against life-threatening infections from encapsulated bacteria (11). Disruption of these mechanisms, as occurs in splenectomized individuals, young children, the elderly and in transgenic animals lacking the chemokines or integrins that participate in the activation and migration of MZ cells, are associated with significant morbidity and mortality (12)(13)(14)(15).…”

Long-term evaluation of the beneficial effect of subtotal splenectomy for management of hereditary spherocytosis

“…27,28 In humans, optimal protection is likely to depend on the residual splenic mass [29][30][31] and on the preservation of adequate blood flow. 32 To obtain a splenic remnant accounting for 25% of the volume of a normal spleen required that approximately 90% of the volume of an enlarged spleen be removed. This is achieved by preserving the splenic tissue supplied by a single pedicle.…”