Human splenic Fc receptor function and dysfunction: definition by circulatory clearance rate compared to computerized kinetic scintigraphy

In vivo reticuloendothelial Fc receptor function was studied in 14 individuals. To assess this function Tc-99m-labeled IgG-coated autologous erythrocytes were injected intravenously and circulatory clearance rates of radioactivity were determined. In 12 individuals [6 normals and 6 patients with systemic lupus erythematosus (SLE)], kinetic computerized scintigraphic imaging of various internal organs was compared to circulatory clearance rates. Both circulatory clearance rates and percentage splenic uptake (PSU) were significantly depressed in patients. The difference between patients and normals was more significant for PSU than for circulatory clearance. Splenic uptake curves showed significantly less linearity for patients, suggesting that splenic defects in SLE are not only quantitative, but also are qualitative. Understanding the nature of immune clearance defects in immune complex mediated diseases may allow for a more rational approach to treatment of patients with these disorders.     

Effects of mannose and mannose derivatives on the clearance of IgG antibody-coated erythrocytes in the rat.

The effects of D-mannose, mannose dimers, mannan, or lactotransferrin [a glycoprotein containing mannose alpha-(1,6) linkages] infusion on the clearance of IgG-coated, 99mTc-labelled, autologous red blood cells (IgG-RBC) by the spleen and liver were investigated in the rat. Untreated autologous rat RBC labelled with 111In were simultaneously injected to correct for 99mTc present in the blood contained in each organ. In normal rats, the mean specific spleen uptake (per g) of IgG-RBC was about 10 times higher than the mean specific liver uptake (per g). Consistent with the clearance curves of IgG-RBC, the mean specific splenic uptake of those RBC significantly decreased after D-mannose, mannose dimers, mannan, or lactotransferrin injections, compared with that measured in normal rats or in control rats receiving i.v. physiological saline, 5% or 15% glucose. In contrast, the mean specific liver uptake of IgG-RBC remained unchanged under otherwise identical experimental conditions. The splenic blockade induced by mannan and mannose derivatives was dose-dependent, C3-independent and spontaneously reversible within 42 hr. Splenic macrophages isolated from mannose- or mannan-treated animals expressed a decreased receptor activity for the Fc domain of IgG, whereas no consistent effect on the C3 receptors was noted. These data show a transient and specific impairment of the Fc(IgG)-receptor function of rat splenic macrophages after the i.v. injection of D-mannose or of mannose derivatives. They support the concept that simple sugar compounds can exhibit immunoregulatory activities in vivo, as has been already shown in vitro.     

Reticuloendothelial Fc receptor function in SLE patients. II. Associations with humoral immune response parameters in vivo and in vitro.

We studied the relationship between reticuloendothelial Fc receptor function and some parameters of the humoral immune response in vivo and in vitro in 18 SLE patients. Fc receptor-mediated immune clearance correlated remarkably well with (a) a decrease of antigen specific IgG after immunization with a primary test antigen (alpha-Helix pomatia haemocyanin) (P less than 0.01) and (b) the spontaneous IgG release in vitro of B cells obtained from peripheral blood (P less than 0.01). These two parameters were significantly interrelated. Reticuloendothelial Fc receptor function was not related to serum IgG levels. The study provides evidence for an association between polyclonal B cell activation and Fc receptor-mediated immune clearance in SLE patients. The possible nature of this association is discussed.     

Quantitative reticuloendothelial function of liver and spleen in man

A method for separate determinations of liver and spleen reticuloendothelial function, using a small-size 99Tcm -antimony sulphide colloid and gamma camera technique, is described. Several methods for achieving blood-background correction are examined, and it is shown that, by a three-compartment model, the use of a specific blood pool tracer can be dispensed with. Hepatic and splenic uptake of the colloid can be described by first order kinetics, and can be calculated to an error less than 5%. In a reference material (n = 13), hepatic and splenic clearance was 262 ml/min (100-412) and 22 ml/min (0-62), respectively. In cirrhosis (n = 7), hepatic clearance was decreased and splenic clearance increased. The results indicate that this method, which is well suited for clinical studies and which is based on a reasonable physiologic model, in cirrhosis of the liver demonstrates a decreased hepatic reticuloendothelial function with (compensatory?) increase in that of the spleen.     

Low-grade intravascular coagulation and reticuloendothelial function

The present study evaluated the influence of experimentally produced intravascular coagulation on reticuloendothelial (RE) stability. Intravascular coagulation was initiated by the intraperitoneal injection of bovine thrombin (500 U/100 g body wt) into male rats. RE function was evaluated by the vascular clearance of an 131I-labeled RE test colloid. Thrombin injection resulted in a transient (0.5-2 h) (P less than .05) depression of the phagocytic index (K) with maximal depression at 1 h postthrombin challenge. The phagocytic index was unaltered after injection of saline or heat-inactivated thrombin. Vascular clearance depression was primarily due to a 37% decrease (P less than .001) in hepatic Kupffer cell colloid clearance and was associated with increments in lung (82%) and marrow (100%) colloid localization with no splenic alterations. While intravascular coagulation was associated with decreased hepatic blood flow at 30 min and 120 min, sinusoidal flow was normal during maximum RE impairment at 60 min. The in vivo clearance depression was not reflected as an intrinsic Kupffer cellular deficit when evaluated in an in vitro system. The results indicate a transient RE dysfunction during intravascular coagulation, the mechanism of which remains to be elucidated.     

Nuclear imaging and the assessment of human Fc receptor function: Studies in systemic lupus erythematosus

In vivo immune clearance of immunoglobulin G sensitized autologous erythrocytes (rbc) was studied in nine patients who fulfilled American Rheumatism Association (ARA) criteria for systemic lupus erythematosus (SLE). Opsonized rbc were radiolabelled with technetium 99. The rate of radioactive blood clearance was measured, as was organ-specific radioactive uptake utilizing area-of-interest (AOI) measurements in a computerized scintigraphic imaging system. It was shown that dynamic quantitation of an AOI corresponding to the heart generated time-activity curves which approximated blood-clearance curves. Calculation of first order clearance (min per 50% decrease in counts) showed a highly significant correlation between rates derived from heart AOI curves and those derived from blood-clearance curves (r = 0.9483, P = 0.0003). Clearance curves showed a monoexponential slope in most patients. Further exploration of organ-specific AOI curves showed that percent splenic uptake and the nature of the splenic uptake curves varied between patients. These studies point toward a variable splenic role in Fc receptor function for SLE patients and further demonstrate the utility of nuclear imaging in studying immune clearance.     

Interferon production of vitro by leucocytes from patients with systemic lupus erythematosus and rheumatoid arthritis.

The production of interferons (IFN) by peripheral blood leucocytes from normal donors an patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) has been investigated in response to several IFN inducers in vitro. Whereas IFN responses of RA donors did not differ significantly from the normal group, those of SLE patients were significantly reduced, and many of these patients failed to respond to all. Patients with active or acute SLE responded significantly less well than those with inactive disease. There was no apparent effect of steroid therapy on the IFN responses of either SLE or RA patients. These data may indicate a basic immunological defect of the circulating leucocytes of SLE patients, which may be responsible for some of the in vitro lymphocyte anomalies reported for this disease.     

Reticuloendothelial Fc receptor function in SLE patients. I. Primary HLA linked defect or acquired dysfunction secondary to disease activity?

Reticuloendothelial system (RES) Fc receptor-mediated immune clearance was measured in 18 patients with systemic lupus erythematosus (SLE). Only two patients, with major disease activity, had a prolonged T 1/2 of the blood disappearance curve of injected IgG coated red cells in comparison to 22 healthy controls. Circulating immune complexes (CIC) were studied with three methods: PEG precipitation, C1q-ELISA and the indirect granulocyte phagocytosis test (IGFT). The T 1/2 of the blood disappearance curve related significantly to the IGFT (r = 0.55, P less than 0.05) and not to the PEG and C1q-ELISA test. Although HLA-DR3 phenotype frequency was significantly increased in our SLE population (P less than 0.05), it was not related to Fc receptor function. Similarly, HLA-DR2 phenotype was not related to RES Fc receptor function. These data do not support the concept that a genetic HLA linked defect in reticuloendothelial Fc receptor function is a primary cause of SLE, predisposing the inflicted individual to immune complex deposition. However, Fc receptor-mediated immune clearance seems to be related to disease activity itself and to levels of CIC.     

Theophylline pharmacokinetics in patients with liver diseases with reference to estimated hepatic blood flow]

Pharmacokinetics of theophylline were determined in patients with liver cirrhosis and idiopathic portal hypertension with reference to estimated hepatic blood flow assessed by indocyanine green (ICG). Decreased plasma clearance of theophylline was noted in patients with liver cirrhosis and the clearance was significantly lower in Child C group than in Child A, B groups (17.5 +/- 3.4 ml/Kg/hr vs 27.6 +/- 8.7, p less than 0.05). Theophylline has been classified as a drug with a low hepatic extraction ratio and it has been believed that changes in hepatic blood flow have little effect on its clearance. The results of present study indicate that theophylline clearance is basically not related to ICG clearance but to theophylline extraction ratio, supporting the common belief. However, it is noteworthy that the clearance was related to decreased hepatic blood flow rather than extraction ratio in a cirrhotic patient with huge extrahepatic shunt, suggesting that hepatic clearance of this drug could be affected by hepatic blood flow under some circumstances.     

Cachectin/tumour necrosis factor-alpha in the circulation of patients with rheumatic disease

By means of a sensitive double-antibody radioimmunoassay, cachectin/tumour necrosis factor-alpha (TNF) was measured in sera from 51 patients with rheumatic disease. Elevated levels of circulating cachectin/TNF were observed in 46% of patients with rheumatoid arthritis (RA; p less than 0.001 versus blood donors) and in 29% of patients with systemic lupus erythematosus (SLE; p less than 0.05 versus blood donors). Marked elevation of cachectin/TNF occurred in both RA and SLE patients in connection with severe infections. The results show that cachectin/TNF is present in the circulation of certain patients with rheumatic disease, and that although the median cachectin TNF level in SLE patients is lower than that in RA patients, the cachectin/TNF response in SLE patients to severe infections is similar to that in RA patients.     

巨细胞病毒感染和系统性红斑狼疮患者细胞免疫功能的相互关系

本文观察了27例系统性红斑狼疮(SLE)患者,巨细胞病毒(CMV)感染对共NK细胞活性无显著影响,但NK活性大于40％的SLE患者CMV感染率较NK活性小于40％者明显低;CMV感染使患者白细胞介素2(IL-2)水平明显降低,只有高水平(大于110U/ml)IL-2的SLE患者CMV感染率低于IL-2水平低者。CMV感染对SLE患者T细胞亚群CD抗原表达影响不大。     

Expression of TLiSA1 on T cells from patients with rheumatoid arthritis and systemic lupus erythematosus

The expression of a new activation antigen, T cell lineage specific activation antigen (TLiSA1) on peripheral blood T cells from 16 rheumatoid arthritis (RA) and 8 systemic lupus erythematosus (SLE) patients and synovial fluid T cells from RA patients was determined in the context of T cell activation. The percentages of TLiSA1 positive T cells from inactive (4.6 +/- 5.2, mean +/- SE) or active RA (19.3 +/- 8.6) or inactive (1.7 +/- 2.1) or active SLE (8.7 +/- 2.7) were significantly increased compared with that of normal controls (0.7 +/- 0.4) (P less than 0.01). All patients with vasculitis showed relatively high positive percentages. The mean fluorocytometric intensity of TLiSA1 positive T cells from RA and SLE patients was significantly higher than that from normals. Percentages of TLiSA1 positive T cells from synovial fluids (21.8 +/- 4.9%) were significantly increased compared with those from peripheral blood of the same patients, indicating the local activation of T cells in patients with RA. An increase in the expression of TLiSA1 with no increase in the expression of the very late activating antigen 1 (VLA-1) was found in peripheral blood from RA, suggesting a difference in the stage of T cell activation in RA. In RA, there was a clinical correlation with levels of TLiSA1 expression on peripheral T cells. After stimulation with PHA, TLiSA1 positive percentages were increased on Day 2 and continued to increase through 5 days of culture. The maximum expression was obtained on Day 5. An increased number of TLiSA1 positive T cells belonged to OKT8. These results suggest that there is the systemic and the local activation of T cells in RA, following antigen stimulation, or a generalized nonspecific activation of immune system that could provide a means to monitor the abnormal immunologic activity in RA.     

Differential generation of chemiluminescence — detectable oxygen radicals by normal polymorphonuclear leukocytes challenged with sera from systemic lupus erythematosus and rheumatoid arthritis patients

Summary The generation of chemiluminescence (CL)-detectable oxygen radicals by normal human polymorphonuclear leukocytes (PMN) after challenging with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) sera is described. CL was measured in a luminol-dependent assay and referred to a standard obtained when preformed immune complexes (Ic) (human tetanus toxoid-antitoxoid Ic resuspended in normal pooled serum) were tested on PMN. Normal sera gave rise to CL activity by PMN between 0% and 50% of the standard Ic (mean±standard error of the mean (SEM): 20.7±4.8). Sera from SLE and RA patients induced strikingly different biological effects on PMN. SLE sera generally induced a high CL-detectable generation of oxygen metabolites which may be causally related to the intense tissue damage (vasculitis) frequently observed in this disease. In contrast to SLE, RA sera induced a CL-detectable respiratory burst by PMN that was included in the normal range. Thus, the biological effects of these sera in terms of stimulation of toxic oxygen radical generation by phagocytes are quite different. This generation of oxygen radicals might reflect a different clearance of circulating Ic by PMN in SLE and RA disease.Abbreviations CL Chemiluminescence - PMN Polymorphonuclear Leukocytes - SLE Systemic Lupus Erythematosus - RA Rheumatoid Arthritis - Ic immune complexes - TAT tetanus-antitetanus toxoid - TAT-S tetanus-antitetanus toxoid resuspended in pooled, non-inactivated human serum - SEM standard error for the mean - EHM Eagle-Hepes-Medium - PBS phosphate-buffered-saline - RF rheumatoid factor - SPA staphylococcal protein A - ANA antinuclear antibodies - KD kilodaltons - Ag antigen     

Immunomodulation by isoprinosine: effects on in vitro immune functions of lymphocytes from humans with autoimmune diseases.

Isoprinosine (IPS) is a new anti-viral agent which appears to have immunomodulatory activities which include its ability to enhance the in vitro blastogenic responses of normal lymphocytes to mitogens. The present study compares the effects of IPS on the in vitro immune functions of peripheral blood mononuclear cells (PBMC) from systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) patients with its effects on PBMC from normal controls. Each mitogen (Con A, PHA or PWM) was used at its optimal concentration with a range of IPS concentrations (0-25 micrograms/ml). PHA-induced blastogenesis by PBMC from all three groups was enhanced by IPS at or above 5 micrograms/ml. The Con A-induced responses of SLE lymphocytes were significantly enhanced over controls by IPS (P less than 0.02 at 5 micrograms/ml) while those of RA lymphocytes were not. IPS had little effect on PWM-induced blastogenesis by RA lymphocytes but did enhance the blastogenic responses of SLE lymphocytes (P less than 0.01 at 5 micrograms/ml). In contrast, the characteristically high immunoglobulin synthesis by SLE lymphocytes was decreased by IPS. The mechanism responsible for these effects is not known but IL-2 production by patient lymphocytes in vitro which was low for both RA (P less than 0.01) and SLE (P less than 0.02) increased significantly (P less than 0.05) when SLE lymphocytes were cultured with IPS. These data identify IPS as an agent for the study of aberrant immune regulation in autoimmune diseases and suggest that it may have potential therapeutic value in SLE.     

Blood clearance and tissue distribution of 99Tc-labelled pneumococci following splenectomy in rabbits.

Female New Zealand White rabbits, following sham laparotomy, total splenectomy and splenectomy with 50% splenic autotransplantation, have been injected intravenously with 99Tc-labelled type 2 Streptococcus pneumoniae. The blood clearance of isotope has been measured and the numbers of circulating bacteria quantitated by blood culture. On sacrifice of the animals the tissue uptake of the isotope has been measured. The results indicate 98% bacterial clearance from the blood within 7 min. The liver is the principal organ for reticuloendothelial uptake of the bacteria accounting for 60% of the total injected dose; 15% of the isotope clearance occurred in the lungs, and the spleen contributed only 3% of the total bacterial clearance. There was no difference in the observed pattern of clearance following splenectomy and following splenic reimplantation. Following the uptake of the bacteria in the tissues, the isotope dissociated from the bacterium and was excreted in the urine. The secondary rise in blood isotope level consequent upon this release was not accompanied by a secondary bacteraemia.     

Blood clearance and tissue distribution of 99Tc-labelled pneumococci following splenectomy in rabbits

Female New Zealand White rabbits, following sham laparotomy, total splenectomy and splenectomy with 50% splenic autotransplantation, have been injected intravenously with 99Tc-labelled type 2 Streptococcus pneumoniae. The blood clearance of isotope has been measured and the numbers of circulating bacteria quantitated by blood culture. On sacrifice of the animals the tissue uptake of the isotope has been measured. The results indicate 98% bacterial clearance from the blood within 7 min. The liver is the principal organ for reticuloendothelial uptake of the bacteria accounting for 60% of the total injected dose; 15% of the isotope clearance occurred in the lungs, and the spleen contributed only 3% of the total bacterial clearance. There was no difference in the observed pattern of clearance following splenectomy and following splenic reimplantation. Following the uptake of the bacteria in the tissues, the isotope dissociated from the bacterium and was excreted in the urine. The secondary rise in blood isotope level consequent upon this release was not accompanied by a secondary bacteraemia.     

Splenic reticuloendothelial function after splenectomy, spleen repair, and spleen autotransplantation

Overwhelming infection after splenectomy remains a problem despite the introduction of vaccine and antimicrobial prophylaxis. To evaluate prospectively various procedures proposed for salvage of the spleen, we measured reticuloendothelial function for two to five years in 51 patients who had initially presented with abdominal trauma and suspected splenic rupture. The mean percentage of pocked erythrocytes and the clearance of antibody-coated autologous erythrocytes in 8 patients who had splenic repair and in 6 who had partial splenectomy were the same as in 11 controls with intraabdominal injury that did not involve the spleen. The mean percentage of pocked erythrocytes remained significantly elevated in 19 patients who had undergone total splenectomy without autotransplantation of splenic tissue. One of seven patients who underwent splenic autotransplantation had a normal level of pocked erythrocytes 18 months after surgery, and a second patient had only a slight elevation at 24 months. The mean (+/- SEM) half-time clearance of labeled erythrocytes was significantly longer in the group that had total splenectomy without autotransplantation (421.1 +/- 74.5 hours) than in the autotransplantation group (91.6 +/- 20.0) or in the controls (5.4 +/- 2.0). We conclude that reticuloendothelial function was better preserved after partial splenectomy and splenic repair than after splenic autotransplantation, but that autotransplantation was superior to total splenectomy and appeared to be safe. Splenic autotransplantation deserves further study in patients who have had splenic trauma when other surgical maneuvers to save the spleen are not possible.     

Abnormal clearance of soluble aggregates of human immunoglobulin G in patients with systemic lupus erythematosus.

In the present study, we tested mononuclear phagocyte system function in nine healthy controls and 15 SLE patients with complement activating 123I-labelled aggregates of human IgG (AIgG). Clearance half-time of AIgG was 26 +/- 8 min in controls, compared to 58 +/- 27 min in patients (P less than 0.005). Binding of AIgG to erythrocytes was significantly lower in patients, 9.3 +/- 8.1 vs 24 +/- 20% (P less than 0.05). The increase of C3a-levels in plasma was significantly lower in patients than in controls (P less than 0.05 at 3 and 8 min), suggesting less complement activation. Liver and spleen uptake of 123I-AIgG was measured with a gamma camera and expressed as liver/spleen uptake ratios. In patients, the liver/spleen uptake ratios were significantly higher than in controls at 15 min, 3.8 +/- 2.0 vs 2.31 +/- 0.7 (P less than 0.05), due to less splenic uptake of AIgG. Correlations between clearance half-time or liver/spleen uptake ratios and immune complex levels or disease activity were not found. This study indicates that clearance of soluble AIgG is abnormal in patients with SLE, due to decreased splenic uptake of AIgG.     

Evidence for a role of accessible galactosyl or mannosyl residues of Fc domain in the in vivo clearance of IgG antibody-coated autologous erythrocytes in the rat

The potential role of accessible galactosyl or mannosyl residues of IgG in the clearance of IgG-coated autologous red blood cells (IgG-RBCs) by the spleen and the liver was investigated in the rat using rabbit anti-rat RBC IgG antibody molecules differing from each other by their capacity to bind in vitro to peanut agglutinin (PNA) and concanavalin A (Con A), i.e., two lectins that specifically bind to beta-galactosyl and alpha-mannosyl residues of Fc domain, respectively. Those IgG molecules [IgG(PNA) or IgG(Con A)] were separated from the starting anti-RBC IgG antibody batch [IgG(total)] by affinity chromatography on lectin columns. Each IgG-RBC preparation was labeled with 99mTc, and was reinjected iv with autologous rat RBCs labeled with 111In to correct for 99mTc present in the blood contained in each organ. The mean specific spleen uptakes per gram of the three IgG-RBC preparations increased according to the level of RBC sensitization but were at least 10 times higher in each instance than the mean specific liver uptake per gram. Consistent with the clearance curves of IgG(PNA)-RBCs, the mean specific splenic uptake per gram of those RBCs was significantly increased as compared to the same parameters determined using either IgG(total)-RBCs or IgG(Con A)-RBCs. In contrast, the mean specific liver uptakes per gram of IgG(PNA)-RBCs, of IgG(Con A)RBCs, or of IgG(total)-RBCs were not significantly different under otherwise identical experimental conditions. The increase in the splenic removal of IgG(PNA)-RBCs was C3 independent. Furthermore, splenic macrophages isolated from rats were able to bind in vitro significantly more IgG(PNA)-RBCs than IgG(total)-RBCs or IgG(Con A)-RBCs. These data therefore support the concept that, in the rat, the kinetic of removal of IgG-RBCs from the bloodstream by the Fc receptors of splenic mononuclear phagocytes may vary according to the nature of accessible carbohydrates located in the Fc domain of IgG antibody molecules coating the erythrocytes.     

A new look at reticuloendothelial blockade.

The characteristics of so-called reticuloendothelial blockade have been reinvestigated in mice using organ uptake, rather than blood clearance, as the main method of assessment. Blockade was induced by using i.v. dextran sulphate. I.v. 51Cr-labelled sheep red blood cells were used as test particles. Although clearance of colloid from the bloodstream induced prolongation of reticuloendothelial clearance of a subsequent dose of test particles, this was solely due to depression of hepatic phagocytosis and the splenic and bone-marrow clearance remained unimpaired. Because of this highly selective action of i.v. blockading colloid, and because testing via the i.v. route can only provide information about macrophages which line blood channels, the expression reticuloendothelial blockade is entirely inappropriate to describe these phenomena. Unexpectedly, the effects could be quantitated using a wide range of doses of this test particle and saturating doses were not required.