The effect of site and technique of splenic tissue reimplantation on pneumococcal clearance from the blood

The technique and site of reimplantation of splenic tissue influences survival of laboratory animals following intravenous injection of pneumococci. Splenic tissue was prepared by slicing, mincing, or grating the spleen. The tissue was placed subcutaneously, intraperitoneally, retroperitoneally, or in an omental pouch. This study was designed to determine the rate of pneumococcal clearance from the blood stream 16 weeks following splenic reimplantation by four different methods. All animals were challenged with an intravenous 1 mL bolus containing 10(7) bacteria. The New Zealand white rabbits were divided into six groups: intact spleen; splenectomized; spleen slices in an omental pouch; minced spleen in an omental pouch; splenic tissue implanted subcutaneously; and bits of spleen dropped into the peritoneal cavity. Animals with an intact spleen and those with spleen slices implanted into an omental pouch cleared bacteria during the first hour and all bacteria had disappeared at three hours. Bacteremia persisted longer than three hours in the other groups. Splenic tissue had regenerated in all animals with omental pouch implants, in four of six with minced spleen dropped into the peritoneal cavity but in only one with a subcutaneous implant. Reimplanted splenic tissue clears pneumococci from the blood stream best when thin slices of spleen are placed in an omental pouch. This technique also assures successful regeneration of splenic tissue.     

Splenic tissue autotransplantation in rabbits: no restoration of host defense

BACKGROUND: The loss of spleen may increase the incidence of overwhelming sepsis. To prevent this, splenic autotransplantation has been performed in humans and experimental animals. However, there is still controversy about the effectiveness of regenerated splenic tissue in preventing infection. This study explored the effectiveness of splenic tissue autotransplantation in restoring host defense. MATERIALS AND METHODS: Rabbits were divided into three groups: splenic autotransplantation, sham operation, and total splenectomy. Histomorphology, T-lymphocyte count, serum lysozyme levels, hemolysin titers, and pneumococcal clearance were observed as read-out parameters over 24 weeks. RESULTS: Histological study showed that the white pulp was poorly developed and central arterioles were missing in the regenerated splenic tissue of the autotransplanted rabbits. The weight of regenerated spleens recovered 6 months later in the splenic autotransplantation group was 11% of that in the sham operation group and was significantly less than the weight at implantation. There was no significant difference in the number of T lymphocytes or level of serum lysozyme between the three groups. A poor antibody response by the rabbits in the splenic autotransplantation and total splenectomy groups was noted after the primary intravenous administration of sheep red blood cells compared to those of sham operation group. After the challenge with type 3 pneumococci intravenously, pneumococcal clearance from the bloodstream in the splenic autotransplantation group did not differ significantly from that in the total splenectomy group, but was markedly delayed compared with that in the sham operation group. CONCLUSIONS: The low quantity and poor quality of the regenerated splenic tissue contribute to the inferior immunoprotective ability of animals autotransplanted with one-third of the original spleen. This suggests that the regenerated spleen cannot compensate for the immunological function of the original one, especially host resistance to infection.     

自体移植脾巨噬细胞C_(3b)、Fc受体及蛋白质表达的实验研究

目的　探讨自体脾组织移植后的功能状况。方法　采用小鼠进行自体脾组织网膜内移植 ,术后 6个月切取移植脾组织 ,检测巨噬细胞的Fc、C3b受体及蛋白表达。结果　自体移植脾巨噬细胞Fc受体的含量与原位脾相近 ,C3b受体的功能正常 ;蛋白质的表达与原位脾相同。结论　大网膜内自体移植脾组织的功能在细胞水平是正常的 ,移植脾组织具有原位脾的功能。     

脾切除对肺内细菌清除和移位的影响

目的:探讨脾切除对肺内细菌清除及移位的影响,同时观察自体脾组织移植的应用效果.方法:将Wistar大鼠90只随机分为假手术组、脾切除组和半脾移植组,采用肺炎球菌悬液雾化吸入方法攻击动物,观察肺组织学病变,肺内细菌清除和移位状况.结果:脾切除组动物肺组织严重充血肿胀,炎性细胞浸润少,肺内细菌清除功能降低,细菌向肺门淋巴结移位和侵入血流加快,与假手术组比较有显著性差异(P<0.05),但半脾移植组动物能基本恢复对肺炎球菌的抵抗能力.结论:脾切除后动物肺抗菌功能降低,而自体脾组织移植是保留脾功能的有益术式.     

Intraportal splenic autotransplantation in rats: Feasibility and effectiveness

This experiment was designed to see whether or not normal host resistance to infection could be reestablished in splenectomized animals by intraportal autotransplantation of homogenized splenic tissue. Part I studied the feasibility of the technique. Within 1 hr of splenectomy, 16 adult Lewis rats received an intraportal injection of autogenous splenic tissue which had been passed through a 500-μm screen. Five rats died acutely from hemorrhage at the site of injection. The others tolerated the infusion well, both acutely and chronically. The animals developed only transient elevations in liver enzymes; chronic portal hypertension did not occur. Histologically, splenic tissue could be demonstrated within terminal portal venules. Part II assessed the effectiveness of intraportal splenic autotransplantation. Eight to twelve months after splenectomy, autotransplantation, or sham operation, 103 Sprague-Dawley rats were challenged with intravenous boluses of 10⁵ to 10⁸ pneumococci. Mortality was 91% for splenectomized animals, 88% for animals bearing autotransplants, and 59% for controls. Thus intraportal splenic autotransplantation is technically feasible in rats. The grafts are well tolerated by the liver, and splenic tissue is preserved in intimate contact with the blood stream. Even after 8 to 12 months, however, such autografts are not capable of providing normal protection against massive pneumococcemia.     

Decreased phagocytic capacity of autotransplanted splenic tissue

Background: Asplenic patients have an increased risk of infections. Operations such as autotransplantation have been proposed to restore functional splenic tissue after splenectomy, but the protective value of this tissue is unclear. Immune responses such as production of antibody remain impaired in humans and animals even when such tissue is present, and clearance of particles from the blood is reported to be less efficient than by normal spleen tissue. The present study investigated the phagocytic capacity of cells in the regenerated tissue in vitro, free of the confounding effects of hepatic clearance. Methods: Single cell suspensions were prepared from splenic tissue from rats 6 months after splenic autotransplantation or sham operation. Phagocytosis of killed, fluorescein‐labelled bacteria was measured by flow cytometry. Results: Autotransplanted tissue contained fewer phagocytic cells than normal tissue, and these cells phagocytosed less per cell. Phagocytosis by spleen cells was dependent on heat‐labile opsonic factors. Conclusions: Autotransplanted splenic tissue does not restore the phagocytic capacity lost following splenectomy.     

Improved survival with splenic autotransplantation and fibronectin therapy following endotoxin administration in rats

The risk of overwhelming infections is greatly increased after splenectomy. In this experimental study in rats, we investigated whether the administration of fibronectinrich cryoprecipitate can improve the survival rate of splenectomized autotransplanted rats subjected to an intravenous challenge with endotoxin. Inbred Lewis rats were divided into four groups: A, splenectomy; B, splenectomy + splenic autotransplantation; C, splenectomy, splenic autotransplantation + fibronectin treatment, and D, sham. Five months after surgery, rats were challenged intravenously with Escherichia coli endotoxin. Immunoglobulin (IgG, IgM, IgA), complement and fibronectin levels were measured before surgery and endotoxin challenge, and 48 h after endotoxin challenge. The survival rate of splenectomized rats was not significantly improved by autotransplantation of splenic tissue, but was significantly (p less than 0.05) improved by autotransplantation and fibronectin treatment. The levels of fibronectin, immunoglobulins and/or complements were significantly decreased after endotoxin challenge in control and in autotransplanted fibronectin-treated rats. The survival improvement of autotransplanted rats treated by fibronectin is probably due to increased endotoxin phagocytosis and clearance.     

Does survival depend on the amount of autotransplanted splenic tissue?

Susceptibility to Streptococcus pneumoniae infection was studied in 11 groups of rats allocated to sham operation, splenectomy, or splenic autotransplantation of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the removed spleen. Three months later, all rats were exposed intravenously to type 1 Streptococcus pneumoniae (median lethal dose, LD50, for control group). Survivors were killed 13 days after the bacterial challenge. Autopsy showed that more splenic tissue was recovered in rats that received less than 50% splenic tissue compared with those that received 50% or more. More survivors were found among sham-operated rats (47.5%; 95% confidence intervals, 32 to 68) and rats that had 40% splenic tissue implanted (35%; confidence interval, 20 to 54) or those that were found to have regenerated 40% splenic tissue. We conclude that 40% of the spleen should be autotransplanted to protect the rat optimally against infection after splenectomy.     

Splenic resection or heterotopic transplantation of splenic tissue as alternatives to splenectomy. Regeneration and protective effect against pneumococcal septicemia

In 82 male Sprague-Dawley rats, divided into eight groups according to surgical procedure performed (total splenectomy, sham operation and six different modes of splenic conservation), resistance to intravenous injection of 4 X 10(3) CFU of Streptococcus pneumoniae type I was evaluated 16 weeks after the surgical procedures. Significant regeneration of the spleen and almost normal resistance to pneumococci was seen 16 weeks after a two-thirds resection. Pieces of the spleen, implanted subcutaneously or into the greater omentum, also showed marked regeneration; though survival time was prolonged, the mortality among these animals following injection with pneumococci did not, however, differ from that of totally splenectomized animals. Dispersed splenic tissue, injected subcutaneously, intramuscularly, or retroperitoneally, showed less sign of regeneration and had no effect on mortality or survival time in partially vis-à-vis totally splenectomized rats.     

自体脾组织移植后病理学变化的实验研究

目的　研究自体脾组织移植后不同时相点病理形态学变化规律。　方法　健康Wistar大鼠 5 6只 ,雌雄不限 ,体重 10 0～ 12 0 g ,随机分为 7组 ,每组 8只中又设脾切除自体组织大网膜内脾移植组 5只 ,假手术组 3只 ,分别于术后 7、14、3 0、60、90、12 0、180d取脾组织 ,光镜、透射电镜观察。　结果　移植脾组织之重量在术后 7d最轻 ,为 0 .0 72 g ,其后逐渐增加 ,180d时为 0 .5 11g ,各时相点之间有明显差异 (P <0 .0 5 )。病理检查提示移植脾组织经历急性期、缓解期、修复期三个病理时期 ,逐步恢复并接近正常的组织结构。　结论　自体脾组织大网膜内移植术是简便有效的脾移植方法。自体移植脾组织再生过程可分为 :急性期、缓解期与修复期     

Serum antibody responses to pneumococcal vaccine after splenic autotransplantation

Immunization with pneumococcal capsular polysaccharide vaccines is advocated after splenectomy; however, experimental and clinical data suggest an impaired antibody response in splenectomized individuals. This study examined the value of splenic autotransplantation at various sites in augmenting the antibody response to Type III pneumococcal capsular polysaccharide in mice immunized 3 months after operation. Splenectomy resulted in impaired antibody responses compared to sham-operated mice (p less than 0.001) using an enzyme-linked immunosorbent assay. Mice with intraperitoneal splenic autotransplants, but not mice with subcutaneous or intramuscular transplants, had greater antibody responses compared to splenectomized mice (p less than 0.05). Antibody responses were elevated only in mice autotransplanted with 50% or more of the original splenic mass. Since autotransplantation of splenic tissue augments the antibody response to pneumococcal capsular polysaccharides, the combination of splenic autotransplantation and pneumococcal vaccination may confer more protection than either modality alone in individuals who must undergo splenectomy.     

Penicillin and natural immunity protect against postsplenectomy sepsis

Prophylactic penicillin, splenic autotransplantation, and immunization using pneumococcal vaccine have all been shown to reduce the incidence and mortality of postsplenectomy sepsis. However, little is known regarding the effect of penicillin in established infection or the effect of prior infection in either asplenic controls or animals with autotransplanted splenic tissue. An animal model with bacterial introduction via the lungs was used to investigate the effect of penicillin, splenic autotransplantation, and previous exposure to the infecting organism on the mortality of postsplenectomy sepsis. One hundred fifty-nine rats underwent either sham celiotomy, intraperitoneal splenic autotransplantation, or splenectomy. Twelve weeks postoperatively all animals were challenged using Streptococcus pneumoniae delivered transtracheally. Half of each group received procaine penicillin by intramuscular injection for 5 days beginning 24 hr post bacterial inoculation and mortality was observed. Eight weeks later surviving rats that had received penicillin were reinoculated with the same organism and mortality was again observed. Splenic autotransplantation reduced the early mortality in postsplenectomy sepsis. Prior bacterial exposure reduced the mortality in postsplenectomy sepsis, even in splenectomized animals. Treatment with penicillin produced a marked reduction in mortality even when administration was postponed for 24 hr after bacterial inoculation.     

Pulmonary antipneumococcal defenses after hemisplenectomy

Conservative splenic surgery such as partial splenectomy is advocated for splenic injuries, since splenectomy predisposes individuals to overwhelming sepsis with encapsulated organisms, of which Streptococcus pneumoniae is the most frequently isolated. The respiratory route is argued to be the most likely portal of entry of pneumococci; however, little data exist on the interaction of the spleen and pulmonary defense mechanisms against pneumococcal invasion. We studied the effect of splenectomy, 50% splenectomy (hemisplenectomy), 25% splenectomy, and sham operation on in vivo clearance of live pneumococci from the lungs of male CD-1 mice following an aerosol challenge of pneumococci. Splenectomy impaired pneumococcal clearance from mouse lung pairs and allowed for increased translocation of live pneumococci to tracheobronchial lymph nodes compared to sham-operated controls. Preservation of splenic mass by partial splenectomy improved lung clearance and allowed for fewer bacteria to be cultured from tracheobronchial lymph nodes compared to splenectomized animals. Clearance of live pneumococci from the lungs and survival were directly proportional to the amount of splenic tissue remaining. Splenic factors probably exist which regulate reticuloendothelial cell function throughout the host. Maintaining adequate splenic mass, therefore, is an important consideration when operating for splenic trauma.     

Immunologic function against infection in splenic autotransplanted mice

The increasing recognition of the danger of overwhelming postsplenectomy infection (OPSI) has led surgeons to attempt to maintain splenic function after spleen injury. One technique they use when splenorrhapy or partial splenectomy are not feasible is the deliberate autotransplantation of splenic tissue. But the amount of splenic tissue necessary to prevent OPSI remains controversial, and opinions differ about the importance of the location and size of the splenic fragments implanted. The mice were divided into five groups, I. splenectomy, II. splenectomy +30% of the spleen implanted intraperitoneal site, III. splenectomy +50% implanted intraperitoneally, IV. splenectomy +50% implanted subcutaneously and V. Sham operation. This study assessed the blood flow of the splenic tissue, increasing weight of splenic mass, histology, the serum level of the immunoglobulins (IgG, IgA, and IgM), pneumococcal antibody titers after vaccination, and survival after intravenous pneumococcal challenge. This study demonstrated that intraperitoneal transplantation showed better regeneration and afforded better protection from OPSI than subcutaneous transplantation. And 30 to 50 percent of the whole splenic tissue mass protected against experimental pneumococcal sepsis. The splenic autotransplants developed in volume and blood supply after 8 weeks, and immunologic function against infection recovered at the same time.     

Splenic autotransplantation provides protection against fatal sepsis in young but not in old rats.

Splenectomy increases the risk of contracting infections with high mortality. Thus, splenic tissue should be repaired orthotopically whenever possible. If all attempts fail, splenic autotransplantation might be a suitable method for splenic salvage. The protective function of such transplants in adults has been questioned, leading to a decreased frequency of splenic autotransplantations. However, the regeneration of splenic tissue is better in the young organism than in the old, suggesting that the protection provided by regenerated splenic tissue might be more reliable in children than in adults. In addition, children are at a higher risk in the case of overwhelming postsplenectomy sepsis. The protection warranted by regenerated splenic tissue after autotransplantation at different ages was examined using a highly standardized animal model. Sham operation, splenectomy, and splenic autotransplantation were performed on adult, weanling, and newborn rats, and Streptococcus pneumoniae was applied intranasally 9 months after the operation. After pneumococcal challenge about 80% of the splenectomized animals in the different age groups died of infection, whereas only 20% of the sham operated rats died. Regenerated splenic tissue resulting from splenic autotransplantation performed on adult or weanling rats demonstrated no protective function. However, in newborn rats with transplanted splenic tissue, both survival rate and survival time were increased significantly. Determination of lymphocyte subsets in the blood did not allow the protective role of splenic transplants to be predicted. This study indicates that disappointing results of splenic autotransplantation in adult patients should not lead to false pessimism about the role of this operation in children.     

Antibody responses after splenectomy and splenic autoimplantation in rats

The sequential immunologic consequences of total splenectomy, partial splenectomy, and total splenectomy with splenic implantation were investigated in an animal model. Adult male albino rats were divided into six groups: sham operated, total splenectomy, 50% splenectomy, 75% splenectomy, splenectomy with 100% intraperitoneal splenic implantation, and splenectomy with 100% subcutaneous splenic implantation. At 2, 4, and 6 months following operation, animals in each group received a single intravenous injection of sheep red blood cells. Six days later, serum hemolysin titers were measured. Results suggest the following: normal immunologic function could be expected if approximately 50% of the spleen is left in situ; intraperitoneal or subcutaneous splenic implantation improves but does not normalize antibody responses; approximately 25% of splenic tissue left in situ results in better immunologic function than 100% ectopic splenic implantation; and following total splenectomy, antibody responses to intravenously administered antigen may improve with time.     

Splenic phagocytic function after partial splenectomy and splenic autotransplantation

We investigated splenic reticuloendothelial activity after splenic preservation procedures to determine their effect upon the phagocytic function of the spleen. We performed the following procedures in Sprague-Dawley rats: sham laparotomy, total splenectomy, hemisplenectomy, subtotal splenectomy, or total splenectomy with intraperitoneal splenic autotransplantation. At nine weeks after operation, phagocytic function of the spleen was determined by measuring radiocolloid uptake. Mean (+/- SEM) splenic phagocytic indices for sham laparotomy (41.2 +/- 2.9), hemisplenectomy (44 +/- 2.9), and subtotal splenectomy (43.2 +/- 5.2) were similar; however, the phagocytic index was reduced markedly after autotransplantation (15.8 +/- 2.2). These data demonstrate that the phagocytic function of the spleen after hemisplenectomy and subtotal splenectomy correlates highly with the weight of the splenic remnant; however, phagocytic function after autotransplantation remains reduced even after accounting for differences in splenic weight.     

Comparison of omental splenic autotransplant to partial splenectomy. Protective effect against septic death

The possible benefit of either partial splenectomy or splenic autotransplantation as protection against post-splenectomy sepsis was investigated. Sprague-Dawley rats were challenged with intravenous Streptococcus pneumoniae and the incidence of bacteremia and mortality were recorded. Animals were divided into four groups based upon the amount of splenic tissue conserved: total splenectomy (0%), partial splenectomy (62%), splenic autotransplantation (27%), or sham celiotomy (100%). A statistically significant (P 0.05) decrease in the incidence of septic death was seen in comparing the total splenectomized animals (63%) to the autotransplant group (27%), the partial splenectomy (4%) and the control group (4%). This diminishing mortality is inversely proportional to the amount of splenic remnant in the respective groups. There was a similar, parallel relationship in the incidence of Streptococcus pneumoniae bacteremia. Thus, the greater the amount of remaining splenic tissue, the lower the incidence of bacteremia and subsequent mortality, implying the preservation of immunologic function with splenic conservation.     

Overwhelming pneumococcal infection in rats immediately after splenectomy

A rat model was used to evaluate the possibility that a nonspecific factor of splenic origin, promoting opsonization and/or antibody production, could affect the susceptibility to pneumococci after splenectomy. Streptococcus pneumoniae type 1 4 × 10³ CFU was injected intravenously in Sprague-Dawley rats. In Experiment I, two groups of previously splenectomized rats (15 at 7 weeks and 15 at 14 weeks of age) were challenged with pneumococci at the age of 15 weeks. All these rats succumbed with no difference in survival time between the two groups. In contrast, the entire control group of 10 nonsplenectomized (sham-operated) rats challenged peroperatively with pneumococci survived. In experiment II, 62 animals were divided into two equal groups. One group was splenectomized when 9 weeks old, and the other was subjected to omental resection (sham operation) at the same time. Two weeks later splenectomy was performed on previously oment-resected animals and the remaining animals were sham-operated. At the second operation all animals were challenged with pneumococci. In each group 74% died and survival times did not show any difference between the two groups. In experiment III splenectomy was performed on 37 9-week-old rats. Two weeks later 20 of these were subjected to omental resection, and in the remaining 17, intraabdominal deposition of homologous dispersed splenic tissue was carried out. Peroperatively, pneumococci were injected intravenously. No difference between the two groups as regards mortality rate or survival times was registered. These experiments revealed no factor remaining briefly after splenectomy that could affect the susceptibility to intravenous injection of Streptococcus pneumoniae type 1.     

Influence of splenectomy, partial splenectomy and splenic artery ligation on E. coli sepsis in rats

Male Sprague-Dawley rats were allocated to four groups--sham operation, partial splenectomy, splenic artery ligation or total splenectomy, and 4 weeks after the operation 3 x 10(8) colony-forming units of Escherichia coli were injected intraperitoneally. Among the splenectomized rats the mortality was significantly (p less than 0.02) increased compared with the controls, while both partial splenectomy and splenic artery ligation did not influence survival. Blood clearance and organ (liver, spleen and lungs) uptake of intravenously injected, radiolabelled, heat-killed E. coli were determined 1 hour after the intraperitoneal challenge. Splenectomy caused a significant decrease in blood clearance. Splenic uptake of radiolabelled E. coli was significantly reduced following partial splenectomy and splenic artery ligation. The splenic operations increased hepatic uptake expressed per gram tissue. Splenectomy thus resulted in reduced blood clearance and increased mortality in Gram-negative sepsis, while the reduced splenic uptake following partial splenectomy or splenic artery ligation did not influence blood clearance of E. coli or mortality.