Optimal site and amount of splenic tissue for autotransplantation.

Clinical and basic studies have documented a high susceptibility to pneumococcal infection in asplenic humans and animals. It has been suggested that autotransplantation of splenic tissue might be a method of providing host resistance when total splenectomy is necessary. However, the effect of splenic autograft has remained controversial. This study was performed to evaluate the most effective site and amount of splenic autograft using rats. Rats were divided into five groups for the purpose of determining the site of splenic autotransplantation: splenectomy, sham operation, implantation into the omental pouch, intraperitoneal implantation, and intramuscular implantation. For determining the amount for autotransplantation, the rats were divided into seven groups: splenectomy, sham operation, and implantations of 25, 50, 100, 200, or 300 mg of splenic tissue. All animals were challenged with Streptococcus pneumoniae type 6, 16 weeks after surgery. Howell-Jolly bodies appeared postsplenectomy, but disappeared in the implanted rats 16 weeks after the operation. Histologically, the implanted tissue was indistinguishable from that of a normal spleen. Pneumococcal clearance from the bloodstream and survival rate were significantly higher in rats implanted in the omental pouch as compared with splenectomized rats. Intraperitoneal and intramuscular implanted rats did not show a significant difference from the splenectomized rats. More than 50% of splenic tissue for autograft showed a significant increase in pneumococcal clearance and survival rate as compared with that of splenectomized rats. It was suggested that the most effective site of autotransplantation is the omental pouch and approximately 50% of the whole spleen would be necessary for prevention from sepsis.     

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.     

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.     

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.     

自体脾移植联合食管横断吻合术治疗肝硬化门静脉高压症

目的 探讨腹膜后自体脾移植联合食管横断吻合术治疗肝硬化门静脉高压症的临床疗效.方法 将2003年1月至2006年12月收治的36例肝硬化门静脉高压症患者随机分为自体脾移植组(n=18)和脾切除组(n=18),自体脾移植组接受脾切除、食管横断吻合及自体脾移植术,脾切除组接受脾切除、食管横断吻合术.于术前及术后2～6个月定期观察两组患者的一般情况、行脾脏放射性核素扫描,同时检测肝功能、血清促吞噬素(Tuftsin)及IgM水平,并行组间及手术前后比较分析.结果 自体脾移植组患者术后2个月血清Tuftsin和IgM水平与术前比较无明显差异(P0.05),而脾切除组患者术后2个月血清Tuftsin和IgM水平较术前明显降低(P<0.05);自体脾移植术对患者肝功能无明显影响;术后2个月放射性核素扫描证实移植脾于腹膜后存活.结论 自体脾移植对保留机体脾脏免疫功能具有重要价值,腹膜后自体脾移植联合食管横断吻合术治疗肝硬化门静脉高压症的临床效果确切,值得推广应用.     

腹膜后自体脾移植术在肝硬变门静脉高压症治疗中的临床研究

目的　观察腹膜后自体脾移植联合食管下段横断术治疗肝硬变门静脉高压症的临床效果。方法　将20例肝功能Child A、B级的肝硬变门静脉高压症患者随机均分为自体脾移植组和切脾组。自体脾移植组采用自体带蒂脾组织腹膜后移植联合改良的食管下段横断术,切脾组则采用脾切除联合改良的食管下段横断术。以患者术前的情况为对照,在术后2~6 个月观察患者的一般情况、脾扫描、肝功能、血清促吞噬素(tuftsin)及IgM水平。结果　术后第6天切脾组死亡1例,术后第10天脾移植组出现再出血1 例。自体脾移植组术后血清tuftsin、IgM水平高于切脾组,差异有显著性意义(P<0.01),而对肝功能无明显影响。结论　腹膜后自体脾移植能维持脾脏的基本免疫功能,且能长期存活,在临床上推广应用是可行的。     

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.     

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.     

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.     

Response to immunization after partial and total splenectomy

Survival after infection from Streptococcus pneumoniae in both animals and man is influenced by the amount of splenic tissue. We investigated the effect of differences in splenic weight upon the antibody response to immunization and the effect of immunization upon survival after pneumococcal challenge. Young Sprague-Dawley rats had either sham operation, hemisplenectomy, splenectomy with splenic autotransplantation, or total splenectomy. Nine weeks later, rats were immunized with a heat- and formalin-killed type-specific pneumococcal vaccine. Antibody response measured by radioimmunoassay was similar in all operative groups and was significantly higher than in nonimmune rats (P less than 0.01). Splenic weight was less after hemisplenectomy or autotransplantation than in sham-operated animals (P less than 0.01). Immunization improved survival after live pneumococcal challenge in rats that had autotransplantation and total splenectomy (P less than 0.001). Our results demonstrate that splenic weight does not affect the antibody response to pneumococcal immunization in rats. Immunization improves survival after bacterial challenge in susceptible animals and minimizes the detrimental effect of reduction in splenic mass.     

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.     

IMMUNE CELL SUBPOPULATIONS IN REGENERATED SPLENIC TISSUE IN RATS

Background : Asplenic patients have an increased risk of infections. Operations such as autotransplantation or splenic artery ligation have been suggested to ensure retention of functional splenic tissue after splenectomy, but their protective value is unclear. Immune responses, such as production of antibody, remain impaired in humans and animals even when such tissue is present, and phagocytosis is less efficient than by normal spleen tissue. In the present study the cellular composition of regenerated tissue is determined. Methods : Splenic tissue was obtained from rats 6–9 months after splenic autotransplantation, splenic artery ligation or sham operation. The lymphocyte and macrophage subpopulations were labelled using a panel of monoclonal antibodies and analysed by flow cytometry. Results : Both the total number of cells and the number of cells per gram of tissue were significantly reduced. There was a substantial reduction in the percentage of some of the cells examined (CD4⁺ and CD8⁺ T lymphocytes subsets), but not all (B lymphocytes, ED1⁺ and ED2⁺ macrophages, OX2⁺ and OX6⁺ cells). Conclusions : The reduction in the T lymphocyte subsets in regenerated splenic tissue compared with the normal spleen might explain the immunological dysfunction which persists after splenic autotransplantation. The reduction in the number of macrophages may be responsible for the alteration in phagocytic efficiency of regenerated splenic tissue.     

Relative merits of partial splenectomy, splenic reimplantation, and immunization in preventing postsplenectomy infection.

Partial splenectomy, splenic autotransplantation, and immunization with pneumococcal vaccine have been reported to protect patients against overwhelming postsplenectomy infection, and this study was undertaken to evaluate these therapeutic alternatives. For this purpose 136 rats were divided into experimental groups: 34 controls, 34 splenectomy, 34 partial splenectomy, and 34 splenic autotransplantation animals. Five weeks after operation, two-thirds of the animals were immunized with killed pneumococci. The effects of operation and immunization were studied by challenging the animals intravenously with pneumococci. Pneumococcal antibody titers were determined, and phagocytic uptake of pneumococci by the spleen and liver was measured. Immunization impressively increased the survival rate in all groups. At low-challenge doses autotransplantation prolonged survival. At higher-challenge doses only partial splenectomy increased survival. Partial splenectomy and control animals had higher antibody titers than did splenectomy and autotransplantation rats. Animals with the highest antibody titers had the greatest splenic and hepatic phagocytic uptake of pneumococci. Partial splenectomy was more efficient in removing pneumococci than was autotransplantation. Thus immunization is one of the most important factors contributing to survival after splenectomy. Partial splenectomy is preferable to splenic autotransplantation because it is associated with higher antibody titers after immunization, better pneumococcal splenic uptake, and improved survival rates.     

Assessment of post-splenectomy residual splenic function. Splenic autotransplants

Splenectomy increases the risk of fulminant sepsis. The present study assesses residual splenic function in patients splenectomized due to traumatic rupture of the spleen; and six cases with splenic autotransplants. Splenic tissue was observed in only 48% of the splenectomized patients and 100% of the autotransplant cases. The two most reliable analytical parameters to assess the presence of functional splenic tissue, were the absence of Howell-Jolly bodies and normal IgM blood levels. In cases where total splenectomy is indicated, it has proved useful to perform autotransplantation of splenic tissue at omentum major level.     

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.     

Autotransplantation of Spleen Mitigates Drug-Induced Liver Damage in Splenectomized Mice

Purpose: The spleen presents numerous functions, including the production of immunoglobulins and blood filtration, removing microorganisms and cellular debris. The spleen also has anatomical and functional relationship with the liver, but there are few studies on this topic. The aim of this study was to assess the effect of splenectomy and autologous spleen transplantation on both filtering functions of spleen and acetaminophen-induced hepatotoxicity. Materials and Methods: Fifty-two BALB/c mice were randomized into four groups: splenectomized; splenectomy and splenic autotransplantation in the greater omentum; sham operated control; and non-operated control. At day 7th, 14th, and 28th after surgery, splenic filtration was assessed by counting Howell-Jolly bodies (HJB) and pitted red cells (PIT). The animals received 400 mg/kg acetaminophen by gavage at day 28^th and after 12 or 24 hours were euthanized for evaluation of splenic and hepatic morphology. Results: The splenectomized group demonstrated reduced filtration of HJB and PIT in all analyzes, while the autotransplanted group developed progressive recovery of function after the 14th day. At day 28 after surgery the implants showed similar histology in comparison to normal spleen. Liver histology showed more intense centrilobular necrosis in splenectomized group in comparison to the others, suggesting a protective role of spleen in acetaminophen-induced liver injury. Conclusions: Splenic implants showed structural and functional recovery, demonstrating the ability of autologous implant to rescue filtering function of intact spleen. Furthermore, the integrity of splenic function appears to influence liver morphology, since the presence of the splenic implants mitigated the effects of chemically-induced liver damage.     

Effects of splenectomy and splenic artery ligation on the portal pressure in portal hypertensive rats.

Immediate, short-, and long-term effects of splenectomy and splenic artery ligation on the portal pressure were studied in animal models experimentally created by partial portal vein ligation. The portal pressure of these animals would usually elevate immediately after partial ligation of the portal vein from a normal level of 6.0 +/- 0.5 to 14.8 +/- 1.3 mm Hg (P < 0.005), which could be maintained at least for 6 months. The portal pressure measured at 2 weeks, 4 weeks, and 6 months after portal vein ligation was 14.0 +/- 2.7, 15.2 +/- 2.7, and 12.7 +/- 2.0 mm Hg, respectively (P < 0.005, as compared with the normal). When splenectomy was performed on these animals at 2 weeks after partial portal vein ligation, the pressure dropped immediately but only transiently from 14.0 +/- 2.7 to 11.0 +/- 3.0 mm Hg, and bounced back to the presplenectomy level in 20 sec. After an additional 2 weeks, the portal pressure in these splenectomized rats was usually at 15.2 +/- 4.2 mm Hg, which was indistinguishable from that of rats whose portal vein was ligated but the spleen was not removed. Six months after splenectomy, however, the portal hypertensive rats had a portal pressure of 17.1 +/- 6.4 mm Hg, which was significantly higher than that of the controls. Splenic artery ligation, on the other hand, did not result in any immediate decrease in portal pressure (14.0 +/- 2.7 mm Hg vs 14.6 +/- 1.4 mm Hg; P > 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)     

Role of the liver in host defense to pneumococcus following splenectomy

Splenectomy is associated with increased susceptibility to bacterial infection, and this is thought to be primarily due to a decrease in clearance of bacteria from the blood. The purpose of the present study was to determine if splenectomy could increase susceptibility to pneumococcus type 3, which is cleared primarily by the liver in rats, and if hepatic function is altered by splenectomy. Splenectomy increased the mortality of rats challenged iv with pneumococcus. Heat-killed, 51Cr-labeled pneumococci were rapidly cleared by the liver and splenectomy did not alter the initial clearance rate or the initial hepatic uptake of bacteria. Injection of viable pneumococci showed that blood levels were unchanged at 30 min but were much greater 5 hr after challenge in splenectomized animals. Hepatic uptake of viable pneumococcus was also not changed at 30 min after injection but at 5 hr the number of bacteria in the liver was greater in the splenectomized animals. This suggests an impairment in hepatic bactericidal function. Another contributing factor may have been that the hepatic bactericidal capacity was overwhelmed by the pneumococci which would normally have been killed by the spleen. Lung localization of viable bacteria was increased initially but there was no decrease in pulmonary bactericidal function. Thus, splenectomy increased susceptibility to a bacteria cleared primarily by the liver which was attributed to an impairment of hepatic bactericidal function and/or an inability of the liver to compensate for the loss of splenic function due to a saturation of the bactericidal system.     

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.     

Regeneration of splenic remnants after partial splenectomy in rats

Splenic regeneration in the rat was measured after removal of 25, 50, or 75% of the spleen, 50% of the spleen with autotransplantation of the excised portion, and splenectomy with autotransplantation of 50% of the spleen. Splenic growth in rats undergoing sham splenectomies served as a control. Splenic mass at 6 weeks and 4 months after surgery was directly related to the remnant size. “Normalized” spleen weights (measured as grams of splenic tissue per 100 grams of rat weight) after 25, 50, and 75% splenectomy were 57, 41, and 38% of controls at 6 weeks, and 77, 71, and 44% of controls at 4 months. All differences were significant at P < 0.03 except those between 50 and 75% splenectomy at 6 weeks, and between 25 and 50% splenectomy at 4 months. A comparison of autotransplanted splenic mass after total splenectomy with that after 50% splenectomy (0.042 ± 0.005 and 0.025 ± 0.004, respectively, at 6 weeks) demonstrated that an intact subtotal spleen inhibited significantly regeneration of the autotransplanted spleen. The effect of autotransplanted splenic tissue on regeneration of a splenic remnant was little to none at 4 months.