Immunological consequences of splenectomy

Primary Care Considerations for Elderly U.S. Veterans of World War II and the Korean War: A Narrative Review

Many of the United States' more than 18 million veterans obtain healthcare through the Department of Veterans Affairs' (VA) Veterans Health Administration system; however, recent legislative changes have expanded veterans' access to non-VA care in their communities, particularly for those who do not live near VA medical centers. Veterans are seen by physicians in outpatient practice across the United States and are admitted to non-VA hospitals; this is particularly salient for older veterans, who may require a more frequent and high level of care. We present a review of characteristics of U.S. veterans from two conflicts: World War II (WWII) and the Korean War. While non-VA clinicians are well equipped to provide care for patients of all different ages, veterans of armed conflicts have a unique constellation of exposures and cultural considerations that must be accounted for when providing them care. In this review, we describe characteristics of the generations of American veterans who served in WWII and the Korean War conflicts in a brief historical context. We then note conflict-specific exposures and potential long-term sequelae to watch for during physical examinations and to monitor thereafter, age-specific health and emotional concerns, and best practices for providing care to this cohort of veterans.

Pathogenesis of Autoimmune Hepatitis-Cellular and Molecular Mechanisms

Pediatric autoimmune liver disorders include autoimmune hepatitis (AIH), autoimmune sclerosing cholangitis (ASC), and de novo AIH after liver transplantation. AIH is an idiopathic disease characterized by immune-mediated hepatocyte injury associated with the destruction of liver cells, causing inflammation, liver failure, and fibrosis, typically associated with autoantibodies. The etiology of AIH is not entirely unraveled, but evidence supports an intricate interaction among genetic variants, environmental factors, and epigenetic modifications. The pathogenesis of AIH comprises the interaction between specific genetic traits and molecular mimicry for disease development, impaired immunoregulatory mechanisms, including CD4+ T cell population and Treg cells, alongside other contributory roles played by CD8+ cytotoxicity and autoantibody production by B cells. These findings delineate an intricate pathway that includes gene to gene and gene to environment interactions with various drugs, viral infections, and the complex microbiome. Epigenetics emphasizes gene expression through hereditary and reversible modifications of the chromatin architecture without interfering with the DNA sequence. These alterations comprise DNA methylation, histone transformations, and non-coding small (miRNA) and long (lncRNA) RNA transcriptions. The current first-line therapy comprises prednisolone plus azathioprine to induce clinical and biochemical remission. Further understanding of the cellular and molecular mechanisms encountered in AIH may depict their impact on clinical aspects, detect biomarkers, and guide toward novel, effective, and better-targeted therapies with fewer side effects.

Case Report: Combination Therapy with Liposomal Amphotericin B, N-Methyl Meglumine Antimoniate, and Pentamidine Isethionate for Disseminated Visceral Leishmaniasis in a Splenectomized Adult Patient

In immunocompromised patients, visceral leishmaniasis (VL) can present with atypical clinical symptoms that include poor response to treatment. No optimal therapeutic regimen is available for such cases. In a splenectomized male patient, we observed a disseminated form of the disease in the liver, bone marrow, lymph nodes, and gastrointestinal tract. There was an apparent clinical improvement when he was initially treated with liposomal amphotericin B (L-AmB), but this was followed by a relapse involving severe clinical symptoms. He was finally treated successfully with a combination of L-AmB, meglumine antimoniate, and pentamidine isethionate. It is important to include asplenia as an immunosuppressive condition that induces exotic VL pathologies. In such cases, combination anti-Leishmania drug therapy should be considered.

The immunity features and defects against primary cytomegalovirus infection post-splenectomy indicate an immunocompromised status: A PRISMA-compliant meta-analysis

BACKGROUND

To evaluate if splenectomy results in severely impaired immune responses against primary cytomegalovirus (CMV) infection compared to the general immunocompetent population.

METHODS

We performed a systemic literature review to study CMV infections in splenectomized individuals, a special population group presently considered immunocompetent to viral infections. We retrieved 30 cases with established CMV infection post-splenectomy and we recorded their disease manifestations, laboratory findings, immunological studies, and histopathology reports. In addition, we retrieved numerous multidisciplinary articles in view of post-splenectomy immunology defects, as well as of immune responses to primary invading CMV in the absence of the spleen. Two clinical studies directly comparing splenectomized with nonsplenectomized individuals under severe iatrogenic immunosuppression as well as the numerically largest review articles of CMV infections in immunocompetent were retained.

RESULTS

Splenectomy results in the loss of spleen's ability to fend-off blood-borne pathogens and impairs the link between innate and adaptive immunity. The major post-splenectomy immune-defects against CMV are: weakened, delayed or absent anti-CMV IgM, and compensatory marked IgG response; severely impaired B-cell and CD4, CD8 T-cells function responses; and post-splenectomy, bone marrow compensates for the absence of spleen's immune responses against CMV, mimicking a monoclonal T-cell lymphoproliferative process.

CONCLUSION

The puzzled diagnosis of the CMV syndrome post-splenectomy is of the most challenging and misleading, resulting in risky and costly interventions and a subsequent prolonged hospitalization (2 months). The mounting multi-disciplinary literature evidence renders us to suggest that splenectomized individuals are not only prone to encapsulated bacteria but also behave as immunocompromised to CMV.

Effects of plant essential oil supplementation on growth performance, immune function and antioxidant activities in weaned pigs

BACKGROUND

The aim of this study was to determine the effects of plant essential oil supplementation on growth performance, immune function and antioxidant activities in weaned pigs.

METHODS

In the study, 24 weaned pigs were used to explore the effects of plant essential oil (PEO) on growth performance, immune properties and antioxidant activities. Pigs were fed with a basal diet (CON) or basal diet containing different concentrations of PEO (PEO50: 50 ppm; PEO100: 100 ppm; PEO200: 200 ppm). After 3 weeks, all pigs were slaughtered and blood and tissue samples were collected for biochemical analysis.

RESULTS

The results showed that PEO supplementation quadratically increased body weight gain (BWG) (P = 0.031), linearly (P <  0.05) and quadratically (P <  0.05) decreased F:G. In addition, IgG increased linearly (P <  0.05) and IgM increased linearly (P <  0.05) and quadratically (P < 0.05) as PEO supplementation. Similarly, MDA in serum, jejunal mucosa and pancreas were linearly decreased (P < 0.05) and GSH in serum (linear and quadratic, P < 0.05), duodenal mucosa (linear and quadratic, P < 0.05) and in ileal mucosa (linear and quadratic, P < 0.05) were notably increased. Futhermore, antioxidant-related genes expression levels of GST in spleen (linear and quadratic, P < 0.05), GPX1 (quadratic, P < 0.05) and SOD1 (linear, P < 0.05) in spleen and GST in liver (quadratic, P < 0.05) were markedly upregulated by PEO supplementation increasing.

CONCLUSIONS

These results suggest that PEO improves growth performance, immune function, and antioxidant activities in weaned pigs, and it may also relieve weaning stress if used as a feed additive in the livestock industry. And that supplementation 200 ppm PEO in diet would seem to be economically feasible.

Population-based cohort study examining the association between splenectomy and empyema in adults in Taiwan

OBJECTIVE

This study aimed to investigate the association between splenectomy and empyema in Taiwan.

METHODS

A population-based cohort study was conducted using the hospitalisation dataset of the Taiwan National Health Insurance Program. A total of 13 193 subjects aged 20-84 years who were newly diagnosed with splenectomy from 2000 to 2010 were enrolled in the splenectomy group and 52 464 randomly selected subjects without splenectomy were enrolled in the non-splenectomy group. Both groups were matched by sex, age, comorbidities and the index year of undergoing splenectomy. The incidence of empyema at the end of 2011 was calculated. A multivariable Cox proportional hazards regression model was used to estimate the HR with 95% CI of empyema associated with splenectomy and other comorbidities.

RESULTS

The overall incidence rate of empyema was 2.56-fold higher in the splenectomy group than in the non-splenectomy group (8.85 vs 3.46 per 1000 person-years). The Kaplan-Meier analysis revealed a higher cumulative incidence of empyema in the splenectomy group than in the non-splenectomy group (6.99% vs 3.37% at the end of follow-up). After adjusting for confounding variables, the adjusted HR of empyema was 2.89 for the splenectomy group compared with that for the non-splenectomy group. Further analysis revealed that HR of empyema was 4.52 for subjects with splenectomy alone.

CONCLUSION

The incidence rate ratio between the splenectomy and non-splenectomy groups reduced from 2.87 in the first 5 years of follow-up to 1.73 in the period following the 5 years. Future studies are required to confirm whether a longer follow-up period would further reduce this average ratio. For the splenectomy group, the overall HR of developing empyema was 2.89 after adjusting for age, sex and comorbidities, which was identified from previous literature. The risk of empyema following splenectomy remains high despite the absence of these comorbidities.

Splenectomy Correlates With Increased Risk of Pyogenic Liver Abscess: A Nationwide Cohort Study in Taiwan

OBJECTIVES

Little is known about the risk of pyogenic liver abscess in patients with splenectomy. We explored the relationship between splenectomy and pyogenic liver abscess in Taiwan.

METHODS

We conducted a nationwide cohort analysis using the hospitalization dataset of the Taiwan National Health Insurance Program. We included 17,779 subjects aged 20-84 years who underwent splenectomy in 1998 to 2010 (splenectomy group) and 70,855 randomly selected subjects without splenectomy (non-splenectomy group). Both groups were matched by sex, age, other comorbidities, and hospitalization year of receiving splenectomy. The incidence of pyogenic liver abscess at the end of 2011 was measured. The multivariable Cox proportional hazard regression model was used to estimate the hazard ratios and 95% confidence intervals for pyogenic liver abscess associated with splenectomy and other comorbidities.

RESULTS

The overall incidence rate was 3.75-fold higher in the splenectomy group than that in the non-splenectomy group (2.15 vs 0.57 per 1000 person-years; 95% confidence interval, 3.57-3.94). After controlling for potential confounding factors, the adjusted hazard ratio of pyogenic liver abscess was 3.89 in subjects with splenectomy (95% confidence interval, 3.20-4.72) when compared with subjects without splenectomy. In further analysis, the hazard ratio markedly increased to 14.34 for those with splenectomy and having any of the assessed comorbidities, including alcoholism, biliary stone, chronic kidney disease, chronic liver diseases, and diabetes mellitus (95% confidence interval, 10.61-19.39).

CONCLUSIONS

Patients with splenectomy are at an increased risk of developing pyogenic liver abscess, particularly when they have comorbid conditions.

Splenectomy Alters Distribution and Turnover but not Numbers or Protective Capacity of de novo Generated Memory CD8 T-Cells

The spleen is a highly compartmentalized lymphoid organ that allows for efficient antigen presentation and activation of immune responses. Additionally, the spleen itself functions to remove senescent red blood cells, filter bacteria, and sequester platelets. Splenectomy, commonly performed after blunt force trauma or splenomegaly, has been shown to increase risk of certain bacterial and parasitic infections years after removal of the spleen. Although previous studies report defects in memory B-cells and IgM titers in splenectomized patients, the effect of splenectomy on CD8 T-cell responses and memory CD8 T-cell function remains ill defined. Using TCR-transgenic P14 cells, we demonstrate that homeostatic proliferation and representation of pathogen-specific memory CD8 T-cells in the blood are enhanced in splenectomized compared to sham surgery mice. Surprisingly, despite the enhanced turnover, splx mice displayed no changes in total memory CD8 T-cell numbers nor impaired protection against lethal dose challenge with Listeria monocytogenes. Thus, our data suggest that memory CD8 T-cell maintenance and function remain intact in the absence of the spleen.

Peripheral blood T lymphocyte subsets in children with congenital asplenia

The aim of the current study was to examine whether a congenital lack of the spleen changes distribution, state of activation and function of peripheral lymphocyte T subsets. Seven children with congenital asplenia (CA) aged 1.5-17 years and seven age-matched controls were tested. By triple-color flow cytometry we examined: (1) the expression of CD3(+), CD4(+), CD8(+), CD19(+), and CD56(+) on lymphocytes; (2) the distribution of CD45RA(+) and CD45RO(+) in CD4(+) and CD8(+); (3) the expression of CD27(+) in the CD4(+) and CD8(+) T-cell-bearing CD45RA(+), CD45RO(+), or CD45RB(+). Lymphocyte proliferative responses and cytokines production (IFN-gamma, IL-6, TNF-alfa, and IL-10) in anti-CD3-induced peripheral blood mononuclear cells were tested. The results indicate (1) a normal distribution of the basic lymphocyte subsets, (2) low CD3(+)/CD8(+) percentage but expressing CD8(+high) and non-significantly elevated CD4(+)/CD8(+) ratio, (3) CD45RA(+high) and CD27(+high) in the CD4(+) and CD8(+) T cell, and (4) CD45RB(+high) in the CD4(+) and CD45RO(+high) in the CD8(+). The distribution of CD27(+) in the CD45RA(+) and CD45RO(+) CD4(+) T cells remained unchanged. However, the percentage of CD8(+)/CD45RO(+)/CD27(+) T cells tended to be elevated. Altogether, these data indicate that CA is connected with (1) the presence CD4(+) T cells expressing the "naive" phenotype (CD45RA(+high) RB(+high) and CD27(+high)), (2) high numbers of activated CD8(+) T cells shifted toward the memory phenotype (CD45RO(+high)) but still showing high CD27(+) expression, which may indicate failure in T CD8(+) cytotoxic effectors differentiation, and (3) a tendency to the rather pro-inflammatory status of cells, low IL-10 expression, and suboptimal lymphocytes responses to mitogenic stimulation.

Splenectomy increases mortality in murine Trypanosoma cruzi infection

The spleen is a secondary lymphoid organ that harbours a variety of cells such as T and B lymphocytes and antigen-presenting cells important to immune response development. In this study, we evaluated the impact of spleen removal in the immune response to experimental Trypanosoma cruzi infection. C57BL/6 mice were infected with Y strain of the parasite and infection was followed daily. Mice that underwent splenectomy had fewer parasites in peripheral blood at the peak of infection; however, mortality was increased. Histological analysis of heart and liver tissues revealed an increased number of parasites and inflammatory infiltrates at these sites. Spleen removal was associated with reduction in IFN-γ and TNF-α production during infection as well as with a decrease in specific antibody secretion. Haematological disorders were also detected. Splenectomized mice exhibited severe anaemia and decreased bone marrow cell numbers. Our results indicate that spleen integrity is critical in T. cruzi infection for the immune response against the parasite, as well as for the control of bone marrow haematological function.

Termografia infravermelha em tempo real como método de avaliação da viabilidade do baço em modelo de esplenectomia parcial em porcos

OBJETIVO: Determinar se a termografia infravermelha é capaz de detectar com precisão a perda de perfusão tecidual em áreas de parênquima esplênico. MÉTODOS: Cinco porcos Landrace pesando entre 12 a 15 kg, após medicação pré-anestésica intramuscular e anestesia por infusão endovenosa, foram submetidos a quatro etapas de ligaduras sequenciais, dos vasos arteriais para o pólo inferior do baço: 1-vasos do ligamento esplênico; 2-ramo da artéria esplênica para o pólo inferior; 3-ramo arterial para o pólo inferior na face visceral do órgão; 4-parênquima esplênico dividindo o órgão. As imagens foram captadas por câmera Therma CAM SC500 instalada a 50 centímetros da superfície do órgão. As temperaturas foram medidas na região proximal (vascularizada) e na região distal (isquêmica), em três áreas circulares distintas de cada região através do software SAT Report, antes e após cada etapa de ligaduras, constituindo cinco grupos de medidas: tempo 0 = antes da etapa 1; tempo 1 = após etapa 1; tempo 2 = após etapa 2; tempo 3 = após etapa 3; tempo 4 = após etapa 4. RESULTADOS: Houve manutenção da temperatura da região proximal (vascularização preservada) durante todos os tempos de desvascularização. A temperatura da região distal (desvascularizada) iniciou queda a partir da primeira ligadura e tornou-se estatisticamente menor que a da região proximal a partir da ligadura 3 (Etapa 3). Houve diferença estatisticamente significativa entre as temperaturas proximais e distais do órgão na medida em que foram sendo realizadas as ligaduras vasculares. CONCLUSÃO: A termografia infravermelha foi capaz de distinguir com precisão áreas de parênquima esplênico com vascularização preservada de áreas isquêmicas e pode contribuir para a avaliação da viabilidade de órgãos sólidos.

Splenectomy does not interfere with immune response to Leishmania major infection in mice

Spleen is one of the largest lymphoid organs in the body; it harbors immune cells including antigen presenting cells, B and T lymphocytes. It has an important role in humoral and cellular immune responses. Herein we investigated the role of spleen in the immune response to experimental Leishmania major infection. It is known that C57BL/6 mice are resistant to L. major infection whereas BALB/c mice are susceptible. Although splenectomy was associated with reduced serum levels of IFN-gamma, absence of the spleen did not change the profile of L. major infection in the resistant C57BL/6 and BALB/c susceptible mice. Both strains of mice maintained the same profile of cytokine production in regional lymph nodes after splenectomy and responded in the same way against the infection. Only splenectomized BALB/c mice had a reduction in IL-4 and IL-10 production by lymph node cells early in infection. Our data suggest that, in localized infections, regional lymph nodes may replace efficiently the immunological role of spleen in the cellular and humoral immune responses.

In Vitro Study of the Long-Term Effects of Post-Traumatic Splenectomy on Cellular Immunity

The purpose of this study was to investigate the effect of splenectomy on cellular immunity. We studied the cellular phenotype and type 1 [interferon-gamma, interleukin-2 (IL-2)] and type 2 (IL-4 and IL-10) cytokine-producing peripheral blood CD4+ and CD8+ T lymphocytes in 22 healthy adults who had undergone post-traumatic splenectomy about 1 to 35 years ago. Splenectomy resulted in a long-term reduction of the percentage of CD4+CD45RA+ cells and a late increase of the percentage and absolute numbers of T-cell receptor gamma/delta cells. Stimulation with Staphylococcal enterotoxin B resulted in normal IL-2 production by CD4+ T cells, indicating that the naïve cells were not anergic. Splenectomy also resulted in long-term priming of both CD4+ and CD8+ T cells. During the first 8 years, both type 1 and type 2 CD4+ T cells were primed to varying degrees. About 8 years later, the percentage of primed type 2 CD4+ T cells subsided, but that of type 1 CD4+ T cells, although decreased, remained detectable over a longer period. Priming of CD8+ T cells persisted throughout the study period. The long-term priming of type 1 CD4+ and CD8+ T cells, which may result in partial impairment of T-cell functions, may explain reported defects of immune responses to recall antigens in splenectomized individuals. In addition, changes in the profile of primed CD4+ T cells with time may be clinically relevant to relapses in autoimmune thrombocytopenia after splenectomy.

Long-term decrease of CD4+CD45RA+ T cells and impaired primary immune response after post-traumatic splenectomy

Congenital or acquired absence of the spleen and functional hyposplenism are associated with abnormalities of host defence such as an increased susceptibility to infection with encapsulated bacteria. The effects of the lack of the spleen on cell-mediated immunity are largely unknown. In the present study we have investigated peripheral blood lymphocyte subpopulations in healthy adults who had undergone splenectomy because of severe abdominal trauma > 4 years before the study. The results show a significant reduction in the percentage of CD4+ T cells due to a selective and long-term decrease in the percentage of CD4+CD45RA+ lymphocytes, the CD4+ T-cell subset mainly involved in primary immune responses to newly encountered antigens. Levels of the reciprocal CD45RO+CD4+ T-cell subset were comparable between splenectomized and control individuals, as were lymphoproliferative responses and IFN-gamma production to recall antigens. Decreased levels of CD4+CD45RA+ cells were accompanied by an impairment in primary immune responsiveness, as assessed by investigating T-cell proliferation to stimulation with keyhole limpet haemocyanin and by measuring antibody responses following primary immunization with a clinically relevant T-dependent antigen, hepatitis A vaccine, in vivo. These findings suggest a possible role of the spleen in the generation, maintenance and/or differentiation of naive, unprimed T cells or their precursors, which might have a possible functional relevance for primary immune responses following splenectomy.

Partial splenectomy in children: an alternative for splenectomy in the pathological staging of Hodgkin's disease

BACKGROUND

The more accurate staging of Hodgkin's disease in children is achieved with a staging laparotomy and splenectomy. A disadvantage of the splenectomy is the high risk for an overwhelming postsplenectomy sepsis (OPSI). Therefore, the partial splenectomy was introduced as an alternative to splenectomy in the staging of Hodgkin's diseases in children.

METHODS

During the period 1982-1988, 12 children with Hodgkin's disease underwent a staging laparotomy with partial splenectomy. All patients were preoperatively vaccinated with Pneumococcus vaccine. The first three patients received 44 Gy locoregional radiotherapy, whereas nine patients received 25 Gy locoregional radiotherapy and two courses of MOPP/ABVD (mitoxin, oncovin [vincristine], procarbazine, prednisone/adriamycin, bleomycin, vinblastine, decarbazine).

RESULTS

The morbidity was negligible. The pathological stage changed in three patients (25%). During a median follow-up of 6 years (range 4-10), no OPSI was diagnosed. One patient developed a secondary leukaemia.

CONCLUSIONS

Staging laparotomy for Hodgkin's disease is being performed with less frequency because the majority of patients are treated with chemotherapy and low-dose radiation therapy. After splenectomy and chemotherapy regimens with alkylating agents, there is an increased risk for secondary acute leukemia. With partial splenectomy an adequate staging of the disease can be achieved, allowing a more tailored therapy so that systemic chemotherapy will not be used as frequently, resulting in a lower treatment morbidity without decreasing survival.

Splenosis is regulated by a circulating factor

Splenic rupture may result in splenosis, the growth of splenic fragments. We used a parabiotic model to test the hypothesis that splenotic growth is governed by a circulating mediator(s). Pairs of C57B1/6 mice underwent side-to-side anastomosis. After 2 weeks, each of four groups underwent a second operation in which one or both of the partners had a sham operation or a splenectomy, or had splenic fragments transplanted into their peritoneums, or some combination thereof. Six weeks later, splenotic fragments were excised and weighed. Spleen fragments involuted when inserted into the pairs that had two intact spleens. In contrast, in pairs with one intact spleen and one set of fragments, multiple splenules developed, whose aggregate mass was approximately half (ratio, 0.53 +/- 0.04 [mean +/- SE]) that of the original transplanted fragments. Significantly more splenosis (P < .01) developed in pairs with no intact spleens and one set of fragments (0.82 +/- 0.04). The pairs with no intact spleens and twice as many fragments had an intermediate amount of splenosis (0.66 +/- 0.08). The authors conclude that (1) splenosis is inhibited by a factor (or factors) that circulates across the capillary network in a parabiotic pair of mice, and (2) the level of inhibition of splenosis appears to be directly proportional to total splenic mass. The authors speculate that spleen-saving operations, even if partial, may decrease the incidence of splenosis in the patient with a shattered spleen.

Bloodless splenic surgery: the safe warm-ischemic time

To assess the feasibility of a technique of bloodless splenic surgery, experiments were performed to determine the safe warm-ischemic time of the spleen. Ten mongrel dogs were divided into two groups. Group I (n = 5) underwent division of all collateral splenic vessels, followed by total splenic artery and vein occlusion for 3 hours. Group II (n = 5) underwent similar collateral devascularization, but with total occlusion of the splenic pedicle for 2 hours. All animals underwent sulfur colloid scintiscanning preoperatively and 2 weeks postoperatively. Blood specimens were analyzed for the presence of Howell-Jolly bodies and immunoglobulin (Ig) G IgG and IgM levels. Pathological examination of the spleens was performed 2 weeks postoperatively. Postoperative scintiscanning showed very poor splenic visualization in two of the five group I dogs. Pathologically these spleens had extensive necrosis. The remaining eight spleens had normal scans, and only mild congestion was noted. Howell-Jolly bodies were found in all group I dogs (mean, 14.6) but in only 2 group II dogs (mean, 0.6). In four group I dogs, a marked decrease in peripheral IgG was noted. Splenic immunoglobulin levels and peripheral IgM were similar in both groups. This study demonstrates that 3 hours of warm splenic ischemia resulted in splenic necrosis and loss of function in 40% of the dogs tested. Two hours of ischemia appears to be safe for dogs; certainly 1 hour should be safe for humans and should allow sufficient time for most splenic surgical procedures.

Splenic autotransplantation and the immune system. Adequate testing required for evaluation of effect

The risk of severe infections after splenectomy, even after many years, is now well established. In attempts to prevent these infections, spleen-saving techniques, including autotransplantation of spleen fragments, have been performed, when possible in combination with vaccination. The problem in autotransplantation is the evaluation of functional activity. The results of the tests used until now often do not seem to correlate very well with the risk of developing an overwhelming postsplenectomy infection (OPSI). This may be related to the fact that the tests used evaluate general functions, and not specific spleen-related functions, such as the capacity to mount a primary response to certain polysaccharide antigens present in the capsule of bacteria known to cause OPSI. In this review, the significance of the spleen in the human immune system is discussed and the effects of splenectomy are described, including the precautions that can be taken to diminish the risk of postsplenectomy infections and sepsis. It appears that postsplenectomy vaccination is more successful when recently developed protein-conjugated polysaccharide vaccines are used. Because the present testing of the function of spleen autotransplants is not adequate, we suggest that new tests should be developed, employing appropriate polysaccharide antigens.

Effects of splenectomy on the development of tumor-specific immunity

We have previously reported on the antimetastatic effects of experimental adoptive immunotherapy using plastic adherent lymphokine-activated killer cells (A-LAK) cells (R. E. Schwarz et al. Cancer Res. 49: 1441, 1989). We have also reported that the spleen is a superior source of lymphocytes for A-LAK cell generation (R. E. Schwarz and J. C. Hiserodt, Med. Hypotheses 28: 165, 1989). This study, therefore, was designed to examine the effects of splenectomy itself on tumor growth in an experimental animal model. Natural killer (NK)-resistant MADB106 mammary adenocarcinoma cells were injected iv into F344 rats to generate multiple lung metastases. Splenectomies (Sx) were performed on Days -6, -3, -1, 0, 1, 3, 6, and 10, counted from the time of tumor injection. Groups consisted of six animals each, and sham-anesthetized and -operated animals served as controls. Splenectomies, if performed between Days -3 and +1, had significant antitumor effects as documented by the number of outgrowing surface metastases (5 +/- 7 vs greater than 300; P less than 0.0001) and by animal survival (greater than 100 vs 21 +/- 3 days; P less than 0.001). However, splenectomies, performed at an earlier or later stage, did not show these effects. Sx did not alter peripheral blood NK activity or the percentages of mononuclear cell subsets except for a slight decrease in the T-helper/T-suppressor ratio (P less than 0.04). Interleukin 2 (rhIL2), given at 2.5 X 10(5) U/kg/day for 3 days immediately after splenectomy, completely abrogated the observed antitumor effects. Subcutaneous tumor rechallenge of long-term surviving animals showed no tumor take in 87% of the animals.(ABSTRACT TRUNCATED AT 250 WORDS)