Platelet-associated immunoglobulins IgG, IgM, IgA and complement C3c in chronic idiopathic autoimmune thrombocytopenia: relation to the sequestration pattern of 111indium labelled platelets

Levels of platelet-associated immunoglobulins (PAIg) IgG, IgM, IgA and complement C3c were related to parameters of 111Indium-labelled platelet kinetics in 17 patients with chronic idiopathic autoimmune thrombocytopenia (cAITP). Elevated levels of PAIg/C3c were found in 14 patients (82%) (PAIgG n = 13, PAIgM n = 11, PAIgA n = 1, PAC3c n = 5). Only PAIgG correlated with platelet counts (RS = -0.71, p less than 0.01). Mean platelet life span (MLS) was shortened in all patients (median 12.0 h, range 0.3-45.6 h) and correlated with the platelet counts (RS = 0.49, p less than 0.05). MLS was correlated with PAIgG (RS = -0.52, p less than 0.05), but not with PAIgM, PAIgA, or PAC3c. The site of sequestration was splenic in 10 patients and splenic-hepatic in 7 patients. Although no significant correlation between either site of platelet sequestration and any of the investigated PAIg/C3c was demonstrable, platelets coated with higher PAIgG levels were more readily sequestrated in the spleen, while elevations of PAC3c were found in 4 out of 7 patients with hepatic involvement.

Splenic trauma and salvage

The traditional view of the spleen as an expendable organ is no longer tenable. In recent years the importance of the spleen in immunologic processes of bacterial clearance, phagocytosis, and antibody formation has been well established. Post-splenectomy sepsis, once only considered a threat in children, is now recognized in adults. Several techniques have evolved since the early 1930s in dealing with splenic injury. These techniques include observation, prevention of iatrogenic injury, auto transplantation, and suture repair in conjunction with hemostatic agents. A recent review of splenectomies done at our institution showed a salvage rate of 97 per cent in children and 6.3 per cent in adults. The preservation of splenic function should be the principal goal in the isolated injury to the spleen; especially for iatrogenic trauma, conservative surgical management is indicated, particularly in children, but also now in adults.

Mechanisms of lymphocytic choriomeningitis virus-induced hemopoietic dysfunction

Results of this study showed that lymphocytic choriomeningitis virus infection causes a marked activation of natural killer (NK) cells not only in the spleen but also in the bone marrow. This activity reached its peak at about day 3 of infection and declined after days 6 to 7. Enhanced NK cell activity was found to correlate with decreased receptivity for syngeneic stem cells in bone marrow and spleen, with the notable exception that decreased receptivity persisted longer in bone marrow. Treatment of infected recipients with anti-asialo GM1 (ganglio-N-tetraosylceramide) significantly increased the receptivity for syngeneic hemopoietic cells. These findings are consistent with the hypothesis that NK cell activation causes rejection of syngeneic stem cells, thus resulting in hemopoietic depression. To understand the mechanisms behind the prolonged decrease in bone marrow receptivity (and bone marrow function in the intact mouse) mentioned above, we followed the changes in the number of pluripotential stem cells (CFU-S) circulating in the peripheral blood and in endogenous spleen colonies in irradiated mice, the limbs of which were partially shielded. It was found that following a marked early decline, both parameters increased to normal or supranormal levels at about day 9 after infection. Because the bone marrow pool of CFU-S is only about 20% of normal at this time after infection, a marked tendency for CFU-S at this stage in the infection to migrate from the bone marrow to the spleen is suggested. It seems, therefore, that as NK cell activity declines, the spleen regains the ability to support growth of hemopoietic cells and the bone marrow resumes an elevated export of stem cells to the spleen. This diversion of hemopoiesis could explain both the long-standing deficiencies of the bone marrow compartment and the prolonged decrease in the receptivity of this organ.

Mechanisms of splenic control of murine malaria: reticular cell activation and the development of a blood-spleen barrier

By complex stromal responses, the spleen controls the course of nonlethal Plasmodium yoelii murine malaria. The course of disease may be divided into four phases. In the immediate postinfective phase, lasting several days, the filtration beds of the spleen are open. Parasitized and nonparasitized erythrocytes, many plasma cells, lymphocytes, and macrophages are sequestered from the blood; and most or all of the parasitized erythrocytes are phagocytized. In the following precrisis phase, approximately 1 week long, there is increasing parasitemia and anemia. The filtration beds of the spleen support large-scale erythropoiesis, lymphopoiesis, plasmacytopoiesis, and monocyte-to-macrophage differentiation. Reticular cells, the stromal cells which form the splenic filtration beds, become activated, showing signs of intense protein secretion and increased branching and mitosis. The locules of the filtration beds appear sealed off from the blood by branches of activated reticular cells. A blood-spleen barrier is thereby formed, protecting splenic hematopoiesis from the parasite. Factors are produced, moreover, which damage intraerythrocytic parasites, producing crisis forms. Crisis follows. It may occur over several days, presaged by the appearance of circulating crisis forms. The filtration beds are opened to the blood. Circulating crisis forms are trapped within the locules of the filtration beds and phagocytized while the stores of reticulocytes produced there in the precrisis period are released to the blood. The malaria, as a result, is no longer patent and the anemia is relieved. In the fourth or postcrisis phase, lasting many months, the normal structure of the spleen is approached. We postulate that reticular cells, normal and activated, have the following functions: to fabricate the locules of the filtration beds; to control the migration of free cells through these beds; to trap free cells, including parasitized erythrocytes, by cell-surface adherence; to open or close the filtration locules, creating a dynamic blood-spleen barrier; to control the circulation of the spleen--by contraction and alignment in normal spleens and by activation and closing of locules in enlarged spleens; to synthesize collagen III; to synthesize factors which influence marrow release of monocytes; and to secrete antiplasmodial substances.

Kinetics of heat-damaged homologous red blood cells in patients with homozygous beta-thalassemia in relation to blood transfusion

The kinetics of heat-damaged homologous red blood cells (HDE) was studied prior to and 7-10 d following blood transfusion in 14 patients with homozygous beta-thalassemia. On the basis of our results, beta-thalassemic patients were classified into two distinct groups. In the first group the pretransfusion HDE extraction efficiency of the spleen was significantly lower than that of the second group and it increased dramatically following blood transfusion. On the contrary, the relatively higher pretransfusion HDE extraction efficiency of the patients of the second group showed a significant decrease after blood transfusion. These differences between the two groups of beta-thalassemics might be attributed to the different qualitative as well as quantitative alterations of the splenic vascular bed occurring in these patients during the course of their disease. Furthermore, there was convincing evidence that part of the HDE mixture was extracted by RES sites outside the spleen, a function which is also affected by blood transfusion.

Splenic hypofunction in the nephrotic syndrome of childhood

The reticuloendothelial system, including the spleen, subserves important immunologic functions. Loss of splenic function results in an increased incidence of severe bacterial infections and is accompanied by thrombocytosis. Several nephrotic children were noted to have remarkably high platelet counts and predisposition to bacterial infection with encapsulated organisms. We, therefore, investigated the splenic function of nine children with primary nephrotic syndrome and measured the phagocytic function of the spleen by sequestration of Technetium-99-labelled heat-treated autologous RBC, administered intravenously. Four children had decreased splenic function. Repeat studies performed in two of these children after remission of the nephrotic syndrome gave normal results. There were six episodes of bacterial infection (3 peritonitis, 1 septic arthritis, 1 cellulitis, and 1 Escherichia coli urinary tract infection) among the four patients with decreased splenic function. There were no episodes of bacterial infection among the five nephrotic children with normal splenic function. Nephrotic patients with decreased splenic function had significantly increased platelet counts (921,000 +/- 196,000; mean +/- SEM) compared to those with normal function (435,000 +/- 46,000; P less than 0.001). Our findings suggest the possibility that some nephrotic children may have decreased splenic function in association with increased susceptibility to bacterial infections.

Teardrop-shaped red cells in autoimmune hemolytic anemia

The presence of teardrop-shaped red cells in peripheral blood has traditionally been felt to reflect altered marrow architecture, namely myelofibrosis. We evaluated two patients with splenomegaly, moderately severe hemolytic anemia due to warm-reactive IgG anti-red cell autoantibody, and bone marrow erythroid hyperplasia without myelofibrosis. A striking predominance of teardrop-shaped red cells was noted upon examination of their blood films. Removal of a spleen containing extramedullary hematopoiesis in one and resolution of splenomegaly in the other were accompanied by disappearance of these cells. Our observations support a role for the spleen and for extramedullary hematopoiesis in the pathogenesis of this distinctive red cell morphologic abnormality.

Burst-promoting activity in anemia and polycythemia

Burst-promoting activity (BPA) in the sera of patients with various types of anemia and polycythemia was compared with that of normal subjects by an in vitro method using mouse bone marrow cells. The control culture contained normal human AB serum instead of sample materials. Results were expressed as a percentage of burst numbers in control cultures. Serum erythropoietin (Epo) levels were determined by a radioimmunoassay. Serum BPA in patients with aplastic anemia (155.4 +/- 56.7%, mean +/- SD) was significantly higher than that in normal subjects (112.1 +/- 29.1%, Wilcoxon's rank sum test, P less than 0.05). However, serum BPA in patients with uremic anemia (122.2 +/- 26.5%), polycythemia vera (101.9 +/- 19.5%) and stress polycythemia (115.5 +/- 25.6%) was not significantly different from normal subjects. There was a correlation between serum BPA and Epo titers in patients with aplastic anemia and paroxysmal nocturnal hemoglobinuria (r = 0.81, t test, P less than 0.001).

["Wandering spleen": preoperative diagnosis by echotomography of the abdomen (review of the literature and report of a case)]

Splenic wandering is a rare condition of upset position of spleen, due to congenital fault or to excessive looseness of the supporting apparatus of this organ. The literature reports about 180 cases thereof, few of which recognized as such before operation. Ultimate investigations, in this limited number of preoperative diagnoses, resulted angiography and hepato-splenic scintigraphy; only three times the diagnosis was correctly placed through ultra-sounds. The authors show a case, confirmed by the operative report, where the ultrasonic test allowed to place the diagnosis with certainty, and, due to a particular lot of circumstances, proved to be better than TAC.

Detection of eosinophil differentiation factor and its relationship to eosinophilia in Mesocestoides corti-infected mice

Eosinophil differentiation activity has been identified using a simple assay to detect eosinophil differentiation in vitro. Two factors were involved in this activity: eosinophil differentiation factor (EDF, Mr 32-64K) and IL-3 (Mr 19-44K). In this paper it is shown that eosinophil differentiation activity (EDA) can be detected in the serum of mice undergoing eosinophilia induced by Mesocestoides corti. This serum activity is shown to follow the ability of spleen cells to produce EDF after stimulation with parasite antigen or pokeweed mitogen. The activity in mitogen stimulated spleen supernatant (MSSS) and serum has a mean Mr of 38K (range 26K-58K). IL-3 is detectable in MSSS but not in serum. The appearance of the EDA is accompanied by an increase in eosinophil precursors in the bone marrow. These reach a peak at about eight to 16 days. A significant blood eosinophilia was detected by 16 days, reaching a peak at 24 days, although blood levels are a poor indicator of the number of eosinophils reaching the tissues. Eosinophils were present in large numbers in the spleen by 14 days and in the peritoneal exudate by 21 days. At peak levels, 5 X 10(7) eosinophils could be recovered from the peritoneal exudate.

Splenic erythropoiesis in rats under hypoxic and post-hypoxic conditions

In rats chronic hypoxia causes extramedullary haematopoiesis mainly localized in the spleen. It is not known how splenic erythropoiesis develops and how it regresses after termination of hypoxia. In this study the spleen of rats exposed to chronic hypoxia was studied by light and electron microscopy; the findings were compared to relevant peripheral blood values. Splenic erythropoiesis begins almost immediately after exposure to hypoxia and reaches its maximum after 2-4 weeks. It occurs mainly in the splenic cords drawing upon local erythroblasts and is accompanied by an increase in splenic weight as well as a decrease in splenic iron stores. After termination of hypoxia marked phagocytosis by splenic cord macrophages diminishes the number of erythroblasts and of erythrocytes with a concomitant increase in splenic iron stores. Thus, splenic erythropoiesis appears to be inhibited as part of a rebound phenomenon and returned to normal by phagocytosis of erythroid cells within 4 weeks after cessation of the hypoxic stimulus.

Defective support of S1/S1d splenic stroma for humoral regulation of stem cell proliferation

Humoral regulation of CFUs proliferation was investigated in S1/S1d mice characterized by a stromal defect, which severely limits in situ proliferation of in vivo colony-forming cells (CFUs). Injection of LPS-W evoked a large enhancement of CFUs numbers in the spleen of normal +/+ mice. S1/S1d mice were found to be refractory to low doses of LPS-W (up to 15 micrograms/mouse) and to have a diminished response to high doses (up to 150 micrograms). Serum transfer experiments showed that S1/S1d mice are not defective in the early elaboration (6 h) of a humoral factor (SHSF), which mediates the LPS-induced splenic stem-cell accumulation. In a serum-free in vitro system post-LPS S1/S1d and +/+ sera induced a similar degree of CFUs proliferation, indicating the ability of S1/S1d mice to produce normal levels of stem-cell-activating factor (SAF). Transfer of potent post-LPS serum from normal mice evoked a poorer splenic CFUs accumulation in S1/S1d mice as compared to normal +/+ littermates. The population size of splenic stem cells in S1/S1d mice parabiosed with normal +/+ mice also showed a limited increase in response to LPS-W injection. This diminished in vivo response of S1/S1d mice was not due to a decreased sensitivity of their CFUs for SAF, since S1/S1d and +/+ CFUs showed similar survival rates in vitro in the presence of SAF. We propose that the defective response of S1/S1d mice to LPS-induced humoral regulators is due to a nonmigratory component of the S1/S1d splenic stroma, which limits splenic CFUs proliferation either by a short-range inhibitory activity or by a deficiency of a local stimulatory activity or nutrient unlike SAF or SHSF, which might act in synergy with SAF.

The effect of abdominal radiation on spleen function: a study in children with Wilms' tumor

Reports of splenic dysfunction in patients with Hodgkin's disease who received radiation therapy to the spleen raise questions concerning impairment of splenic function and the long-term risk of bacterial sepsis in children who receive abdominal radiation for other diseases. Splenic function was studied in 20 children with Wilms' tumor using a quantitative assessment of vacuolated ("pitted") red cells as a measure of reticuloendothelial function. Fourteen children had received abdominal radiation to a field involving the spleen at a median dose of 2000 rads. Their pitted red cells counts were no different from those of 6 children who received therapy without radiation to the spleen or to those of a group of normal children and adults. We conclude that there is no demonstrable long-term impairment of spleen function with radiation doses at or below 2200 rads.

Reticulo-endothelial function in rats with obstructive jaundice

Reticulo-endothelial function was evaluated by measuring the biokinetics of a standardized 99mTc-sulphur colloid using scintillation camera technique in rats with biliary obstruction. There was no difference in the uptake of the colloid in the liver (K1) between sham operation and biliary obstruction at 1 week and 3 weeks. However, when corrected for changes in liver volume, the corrected colloidal uptake rate (cK1) of the liver was significantly decreased in 1 week's biliary obstruction (P less than 0.005 compared with sham operation) and 3 weeks' biliary obstruction (P less than 0.025 compared with 1 week obstruction). Colloidal uptake rate of the extrahepatic reticulo-endothelial system (K2) was significantly increased (P less than 0.005) in rats with 3 weeks' biliary obstruction. Activity distribution of 99mTc-sulphur colloid in 3 weeks' biliary obstruction was significantly decreased in both total organ basis and per gram basis (P less than 0.005). The results demonstrated a depression of RE activity of the liver in biliary obstruction.

Methods of splenic preservation and their effect on clearance of pneumococcal bacteremia

The intravascular clearance of type 3 Streptococcus pneumoniae was studied in Sprague-Dawley rats. Sham celiotomy was performed on 20 animals while another 20 rats underwent splenectomy. Four weeks later, bacteremia was induced by intraperitoneal (IP) injection of S. pneumoniae. Serial cultures of peripheral blood were obtained. Splenectomy produced significant impairment of intravascular clearance of bacteria compared to that noted among control animals (p less than 0.01). Eighty animals were divided into four equal groups: I--splenectomy, II--50% splenectomy with the upper half left in situ connected to the short gastric vessels, III--50% splenectomy with the lower half left in situ connected to the hilar vessels, and IV--splenectomy with implantation of splenic fragments. Pneumococcus was administered IP 16 weeks later. Rats were killed 6 hours after bacterial challenge. Residual splenic tissue was weighed. There was significantly less splenic tissue in Groups II-IV than noted in sham animals after 16 weeks (p less than 0.01). The type of partial splenectomy did not significantly affect the weight of residual splenic tissue 16 weeks later. Implantation did yield viable splenic tissue, though the amount proved significantly less than that resulting from either type of partial splenectomy (p less than 0.01). Mean bacterial counts with time for short gastric (Group II) and hilar (Group III) remnant animals were significantly different from those for the asplenic (Group I) rats (p less than 0.02 and p less than 0.001, respectively). Animals with splenic implants (Group IV) were not significantly different from asplenic rats (Group I). Animals with hilar splenic remnants proved significantly different from those with short gastric splenic remnants (p less than 0.01). Partial splenectomy offers protection against pneumococcal bacteremia, though preservation of the hilar blood supply affords the most benefit. The utility of splenic implantation remains unproven.

Acquired functional asplenia in sarcoidosis

Sarcoidosis is a recently identified cause of functional asplenia that can be diagnosed by radionuclide imaging. A 31-year-old woman with a five-year history of histologically compatible sarcoidosis was found to have nonvisualization of the spleen on technetium 99m sulfur colloid (radiopharmaceutical) liver-spleen scan. This scintigraphic finding was accompanied by poikilocytosis and Howell-Jolly bodies in the peripheral blood smear. A subsequent gallium 67 citrate scan reflected an abnormal increase in concentration of activity in the spleen, suggesting an active inflammatory process.Based upon this constellation of findings, it was concluded that acquired functional asplenia is the result of reticuloendothelial cell replacement via infiltration of the spleen by epithelioid cell granulomas of active sarcoidosis. This case also illustrates the reversibility of functional asplenia of sarcoidosis following adrenocorticosteroid therapy. Functional asplenia in sarcoidosis is now found to have a recognizable radionuclide imaging pattern.

Genetic influences on splenic function in coeliac disease

Splenic function was assessed using 'pitted' erythrocyte counts in 61 first degree relatives of patients with coeliac disease. 'Pitted' erythrocyte counts were normal in 12 parents, but were raised in 20% of 49 siblings and/or children of coeliac patients. First degree relatives had higher 'pitted' erythrocyte counts than normal controls (p = 0.002). The counts were lower in coeliac relatives than in age matched coeliacs (p = 0.0001), but no difference was present between the relatives and coeliac patients whose small bowel mucosa was morphologically normal. Considerable interfamily variation was found in 'pitted' erythrocyte counts, both in the coeliac patients and first degree relatives, and the pattern tended to 'run true' within families. The genetic factor influencing splenic function in coeliac disease is not HLA-linked but seems to be associated with a second, probably recessive, gene influencing the inheritance of coeliac disease.

The influence of splenic weight and function on survival after experimental pneumococcal infection

Splenectomy impairs survival after pneumococcal challenge in rats, while preservation of sufficient splenic tissue can be protective. This study investigated the effects of methylcellulose on stimulation of splenic weight, splenic histology, reticuloendothelial (RE) activity, and survival after pneumococcal infection. Methylcellulose increased spleen weight four- to five-fold but did not improve RE function or survival after infection. These parameters correlated best with the weight of the remnant in animals that did not receive methylcellulose. The functional limitations of splenic autotransplants were not corrected by methylcellulose stimulation of splenic weight. Preservation of a splenic remnant with intact blood supply is preferable to autotransplantation of the spleen to conserve RE capability.