Defective reticuloendothelial system Fc-receptor function in systemic lupus erythematosus

Effect of gluten-free diet on splenic hypofunction of adult coeliac disease

Splenic function has been serially measured by counting pitted red cells in 15 coeliac patients, before and during a gluten-free diet. The basal percentage values of pitted cells decreased significantly during treatment but no correlation was observed between the duration of the gluten-free diet and the percentage of recovery of splenic function over basal values. Out of six coeliacs with pitted cell values consistent with splenic hypofunction, three showed a total recovery after gluten withdrawal. Our data suggest that, contrary to recent reports, hyposplenism in adult coeliac disease is improved by a gluten-free diet, and that environmental factors may be important in determining and maintaining this complication.

Mechanisms of immune red cell destruction, and red cell compatibility testing

The immune destruction of red cells can occur as a complement-mediated intravascular process, or extravascularly, where the red cells are destroyed by macrophages following interaction with cell-bound IgG1, IgG3, and/or C3b. Many of the factors that affect this in vivo destruction are not taken into account during in vitro pretransfusion compatibility testing. At present, even by use of more elaborate tests, it is difficult to accurately predict the fate of a transfused unit of blood. By using some simple information, such as antibody specificity and thermal range, it is sometimes possible to predict the outcome of transfusing a unit of blood that is incompatible in vitro. At other times it may be necessary to utilize 51Cr-labeled red cells to determine the risk of transfusing such units. Because of the paucity of reported clinical correlations, macrophage/monocyte monolayer assays are of little practical value at present.

Platelet-associated immunoglobulin G in childhood idiopathic thrombocytopenic purpura

Platelet-associated IgG was studied in children with acute and chronic ITP and in patients with thrombocytopenic SLE, using the microtiter solid-phase radioimmunoassay. Of the children with acute ITP, 85% had elevated PAIgG levels. The degree of elevation of PAIgG at onset of disease did not correlate with the development of chronicity. Of the children with acute ITP, clinically and hematologically indistinguishable from the rest, 15% had normal PAIgG values. All of 22 children with chronic ITP had elevated PAIgG values. Although there was good correlation between the platelet count and the PAIgG value in children with chronic ITP, the association was not as striking in those with acute ITP; thus, factors in addition to the level of PAIgG may contribute to the thrombocytopenia in the latter group. Patients with SLE and thrombocytopenia had higher values of PAIgG than would be predicted from the platelet count; the PAIgG value is probably not the only factor determining the degree of immune thrombocytopenia.

Effects of castration and sex hormones on immune clearance and autoimmune disease in MRL/Mp-lpr/lpr and MRL/Mp-+/+ mice

The clearance of erythrocytes sensitized with IgG was studied in MRL/Mp-lpr/lpr (MRL-lpr) and MRL/Mp-+/+ (MRL-+/+) mice, which spontaneously develop autoimmune disease. In both strains, an age-dependent decline in clearance of IgG-sensitized erythrocytes was found. Impaired clearance occurred at an earlier age in MRL-lpr mice than in MRL-+/+ mice, correlating with the relative severity of autoimmune disease in these strains. Androgen treatment improved clearance in MRL-+/+ mice but not in MRL-lpr mice, even though autoantibody levels, renal function, and survival were improved. These results suggest that the beneficial effects of androgen on autoimmune disease are not due solely to improved clearance of immune complexes. Castration followed by estrogen administration did not influence immune clearance or autoimmune disease in MRL-lpr mice. These results indicate that impaired immune clearance is a common feature in several autoimmune mouse strains. However, the effects of sex hormones on immune clearance and autoimmune disease may be dissociated in some strains.

Abnormal reticuloendothelial function in patients with active vasculitis and idiopathic membranous glomerulopathy. A study with 99mTc-labeled heat-damaged autologous red blood cells

Reticuloendothelial function was assessed in 11 patients with systemic lupus erythematosus, 8 patients with Wegener's granulomatosus, and 20 patients with idiopathic membranous glomerulopathy by using autologous 99mTc-labeled heat-damaged red blood cells. With this method organ uptake could be measured by quantitative scintigraphy. There was no relation between the T1/2 of the blood disappearance curve and the T1/2 of the splenic uptake curve. The T1/2 of the blood disappearance curve was normal in all three patient groups. However, there was a significant shift from spleen to liver uptake in patients with active systemic lupus erythematosus, active Wegener's granulomatosus, and membranous glomerulopathy in comparison with a control group. There was no relation with age, level of circulating immune complexes, complement level, kidney function, or immunosuppressive treatment. We conclude that an increase of the liver component of reticulo-endothelial function may compensate abnormalities in splenic function. This stresses the importance of quantitative scanning to detect such abnormalities. The study provides evidence for disease related hyposplenism in patients with active systemic lupus erythematosus, active Wegener's granulomatosus, and membranous glomerulopathy.

Triad of glomerulonephritis, antinuclear antibodies, and positive skin immunofluorescence. Variant of systemic lupus erythematosus

We are reporting findings in 13 patients who presented with glomerulonephritis without evidence of systemic disease, but who were found to have positive antinuclear antibody results and immunoglobulin and/or complement deposits at the dermal-epidermal junction of normal skin not exposed to light. There was no evidence of other organ involvement, and serologic tests for systemic lupus erythematosus (SLE) gave negative results. The renal disease is characterized by severe proteinuria, focal or diffuse proliferative glomerular lesions on biopsy, with variable patterns of immunoglobulin deposits. No clinical manifestations or serologic results typical of SLE have developed during prolonged observation. HLA phenotyping carried out in eight of the 13 patients revealed DR2 or DR3 alloantigens or both in seven of the eight patients, an incidence similar to that in patients with overt SLE. Because of the specificity of the skin biopsy immunofluorescence, the similarity of HLA-DR antigens, and a favorable response of the renal disease to therapy, we believe that these patients have a variant of SLE.

Hepatitis B immune complex glomerulonephritis: simultaneous glomerular deposition of hepatitis B surface and e antigens

A case of a 29-year-old homosexual male with chronic hepatitis B infection, cryoglobulinemia, and glomerulonephritis is described. The glomerular lesions were not readily classified, but exhibited features consistent with immune complex deposits, in both peripheral loop (predominantly epimembranous) and mesangial sites. Immunofluorescence studies, which included the use of a monoclonal antibody, showed that HBsAg was present in mesangial deposits but not in peripheral loop deposits. Immunoperoxidase studies employing HRP-conjugated anti-HBc and anti-HBe provided evidence that the epimembranous deposits contained HBe. Studies of the patient's serum revealed high titers of HBsAg, low titers of HBeAg, as well as anti-HBe and anti-HBc. The cryoglobulins contained small amounts of HBsAg, HBeAg, and anti-HBc, but anti-HBe and anti-HBs antibodies were not found. The possible mechanisms accounting for accumulation of HBsAg and HBeAg in glomeruli are discussed. In addition, the literature concerning the nature of hepatitis B antigens found in glomerular deposits is reviewed.

Evaluation of heat-damaged and IgG-coated red cells for testing reticuloendothelial function

In vitro methods for standardising and assessing the reproducibility of reticuloendothelial function tests in man were performed. Variation in the degree of heat-induced red blood cell damage could be detected by both Channelyzer plots and a filtration test of red cell plasticity although the former test was less sensitive and difficult to quantitate. In a consecutive study of the clearance of heat-damaged red blood cells (HDRBC) in 8 patients and 2 normal individuals, consistent changes were demonstrated by both assays although occasionally one assay alone provided inconclusive results. When undamaged red cells were coated with IgG anti-D antibodies, the number of IgG molecules bound per red cell was determined by an indirect antiglobulin radioimmunoassay. With this assay, it was shown that the rate of clearance of coated cells was related to the amount of cell bound IgG anti-D. Some variation in the degree of coating of cells from patients with systemic lupus erythematosus was found although the differences were insufficient to account for the reported reduction in the clearance of IgG-coated cells in patients with this disease. The radioimmunoassay and microhaemagglutination techniques revealed that neither IgG, Clq, C3 or C3d were bound to HDRBC following incubation in autologous serum suggesting that these cells were cleared in vivo by mechanisms unrelated to immune receptor recognition.

Mode of inheritance of decreased C3b receptors on erythrocytes of patients with systemic lupus erythematosus

The erythrocytes of patients with systemic lupus erythematosus have been shown to have a decreased number of receptors for the major cleavage fragment of the third component of complement (C3b). We studied the basis for this decreased number of C3b receptors by measuring the uptake of anti-C3b-receptor antibody on cells from 113 normal subjects, 38 patients with systemic lupus erythematosus, 14 of their spouses, and 47 of their relatives. The normal subjects had 5014 +/- (mean +/- S.E.M.) receptor sites per cell, but the patients and their relatives had significantly fewer sites--2809 +/- 241 and 3167 +/- 196, respectively (P less than 0.0005). The number of sites in the patients' spouses did not differ from normal (P greater than 0.3). Three phenotypes, indicated by the numbers of receptors, occurred in the normal population; a high phenotype (HH, with 5500 to 8500 sites per cell), an intermediate phenotype (HL, with 3000 to 5499), and a low phenotype (LL, less than 3000). These three phenotypes were present in 34, 54, and 12 percent, respectively, of the normal subjects; in contrast, 5, 42, and 53 per cent of patients had these respective phenotypes. Pedigree analyses indicated that these phenotypes were inherited in an autosomal codominant manner. We conclude that the decreased number of C3b receptors in lupus is inherited, not acquired.

Degradation of soluble immunoglobulin aggregates in vitro by monocytes from normal subjects and from patients with systemic lupus erythematosus

The capacity of human peripheral monocytes to degrade soluble immunoglobulin (IgG) aggregates (AIgG) was studied in vitro. Under serum-free conditions peripheral monocytes from normal donors were able to degrade soluble AIgG in a linear and time-dependent fashion. Addition of fresh human or fresh guinea-pig serum to the incubation mixtures caused a marked increase in degradation of the amount of soluble AIgG available. The stimulatory effect of fresh serum was complement-mediated, because it was abolished by heat treatment of the serum and was not seen when C4- or C3-deficient sera were tested. Functional inactivation of C3 receptors on the phagocytes by trypsin also abolished the complement-mediated stimulation, suggesting cooperation between Fc and C3 receptor in degradation of soluble AIgG. No significant differences were found between monocytes from normal donors and those from patients with systemic lupus erythematosus, as far as degradation is concerned in the presence of complement.

Adult-onset Still's disease. Twenty-year followup and further studies of patients with active disease

Eleven female patients with adult-onset Still's disease were followed for 7-36 years (mean 20.2 years) after the onset of their illness. Ten of these patients had a chronic course characterized by remissions and exacerbations of arthritis associated with fever and rash. Five patients had terminal interphalangeal involvement, and carpal ankylosis was demonstrated on x-ray film in 10. Two patients developed a widespread polyarthritis, and renal amyloidosis was diagnosed 10 years after disease onset in the most severely affected patient. In 4 patients studied during an exacerbation of the disease, circulating immune complexes were detected by the staphylococcal A binding assay, but not by the C1q binding assay. Synovial fluid analysis in 1 patient revealed a low C3 level and total hemolytic complement (CH50) together with immune complexes and IgG rheumatoid factor. Immune complexes were not identified in the characteristic Still's rash by immunofluorescence or electron microscopy, although mast cell degranulation, neutrophil lysis, and perivascular fibrin deposition were reminiscent of immune complex--mediated vascular injury. The clinical and laboratory features as well as the long-term course of adult- and juvenile-onset systemic Still's disease are similar, but further studies of genetic markers and immunopathology are required to establish a common pathophysiology.

Factors controlling the intrasplenic transit of platelets

The kinetics of 111In platelets have been investigated in human subjects using a gamma camera and computer system. Time activity curves were recorded over the spleen, chest and liver, following intravenous bolus injection of autologous radio-labelled platelets. Splenic blood flow expressed as the percentage of total blood volume entering the spleen in unit time, and intrasplenic platelet transit time were calculated from the time activity curves. Spleen size was recorded from the camera images. Splenic blood flow increased with increasing spleen size (r = 0.56, P less than 0.001). Platelet transit time showed an inverse relationship with a semi-quantitative estimate of splenic perfusion (i.e. splenic blood flow per unit volume spleen; r = 0.64, P less than 0.001) but was not related to spleen size. At high rates of estimated splenic perfusion transit time appeared to reach a minimum value of about 7 min, whereas at low rates of estimated perfusion, transit time rose sharply to reach levels greater than 20 min. The effect of polycythaemia, taken to indicate high intrasplenic haematocrit on platelet transit time, was also investigated. Patients with secondary polycythaemia had elevated transit times (19 min SEM 1.6, n = 10) compared with primary polycythaemia (9.7 min SEM 0.8, n = 5) and normals (9.6 min SEM 0.5, n = 5). It was concluded that splenic perfusion was important in determining the duration of platelet transit.

Transient reversal of thrombocytopenia in idiopathic thrombocytopenic purpura by high-dose intravenous gamma globulin

Since recent observations indicate that treatment with high-dose intravenous polyvalent intact immunoglobulin leads to a rapid reversal of thrombocytopenia in the idiopathic thrombocytopenic purpura (ITP) of childhood, we decided to apply this treatment to adults with ITP and to test the possibility that the effect of the immunoglobulin might be attributable to transient blockade of the reticuloendothelial system. Using sequential clearance studies of autologous 99mTc-labeled and anti-Rh(D)-sensitized erythrocytes in four adults with ITP who were treated with total doses of 1 to 1.5 g of immunoglobulin per kilogram of body weight, we found that a transient rise in platelet counts to normal levels within four to five days was accompanied by a marked temporary prolongation of the immune-particle clearance time. These data suggest that commercial intravenous immunoglobulin preparations may interfere with phagocyte Fc-receptor-mediated immune clearance. Since platelets in ITP treated with immunoglobulin were fully hemostatic, this type of therapy may allow surgical procedures to be performed safely in patients with this disease.

Complement receptor (CR1) deficiency in erythrocytes from patients with systemic lupus erythematosus

This study reports quantitative information on the concentration of complement receptor for C3b and C4b (CR1) on erythrocytes from normal individuals and patients with immune complex disease. The measurements were performed by an immunoradiometric assay using monoclonal antibodies against CR1. The antibody specificity was confirmed by immunoprecipitation of CR1 from extracts of surface-labeled cells, by inhibition of rosette formation between B lymphocytes and the erythrocytes intermediate EAC14oxy23b, and by the characteristic distribution of the antigen among cells of human peripheral blood. The number of CR1 molecules in erythrocytes from 52 normal individuals was estimated as 1,410 +/- 620. No significant differences in CR1 levels were observed when individuals were grouped by sex, age, or blood groups. In patients with SLE and rheumatoid arthritis, the number of CR1 molecules per RBC was significantly lower, i.e., 600 +/- 307 and 903 +/- 417, respectively. CR1 levels were normal in asthmatics undergoing long-term treatment with prednisone. In SLE patients, significant correlations were found between CR1 levels, C4 hemolytic titers, and levels of circulating immune complexes. In two out of four patients with SLE, CR1 levels increased significantly during remission, showing that the deficiency is, at least in part, reversible. The deficiency in CR1 could be genetically controlled or could represent an epiphenomenon caused by the interaction of the receptor with a ligand present in the circulation of patients.

Clearance mediated by splenic macrophage membrane receptors for immune complexes in cutaneous vasculitis

This study concerns 11 patients with immune complex associated cutaneous vasculitis (5 leukocytoclastic vasculitis or Gougerot Ruiter's disease, 3 essential mixed cryoglobulinaemia, 2 Henoch-Schönlein purpura and 1 Waldenström's hypergammaglobulinaemic purpura). By determining the clearance of 51Cr-labeled IgG sensitized erythrocytes we showed a slight modification in the splenic mononuclear phagocyte system. In patients with Gougerot-Ruiter's disease the clearance of the autologous IgG-coated erythrocytes was delayed in 1 patient, and normal in 2 patients. In contact, the 8 other patients showed accelerated rates of IgG-mediated clearance. There was no statistically significant correlation between clearance rate, serum complement component levels and composition and/or levels of circulating immune complexes. Thus, the accelerated clearance rate suggests an enhanced activity of the mononuclear phagocyte system IgG-Fc receptors.

Kinetics of heat damaged autologous red blood cells. Mechanism of clearance from blood

The kinetics of radiolabelled heat damaged red cell (HDRBC) distribution have been studied in humans using a gamma camera, and compared with the kinetics of other blood cells. Liver uptake of 111In labelled HDRBC was completed within about 10 min of injection; splenic uptake was biphasic with a half time of about 5 min over the first 20 min following injection, and a later half time much longer than this. Activity initially present in the lung fields cleared within 24 h. The rate constants of liver uptake of 99mTc labelled HDRBC and of 111In labelled platelets were very similar; the rate constants of splenic uptake of these 2 particles were also very similar up to about 20 min following injection when the splenic platelet levels became constant and the HDRBC level continued to slowly rise. Splenic uptake and blood clearance of red cells coated with IgG (IgG-RBC), in contrast to HDRBC, were monoexponential. It was concluded that: (1) the blood clearance of HDRBC was due to pooling within, and to irreversible extraction by, the spleen; (2) liver uptake of HDRBC, which was irreversible, was completed within 10 min of injection; (3) IgG-RBC clearance was due to irreversible extraction by the spleen; (4) HDRBC uptake in the lung was unrelated to reticuloendothelial function, and represented prolonged transit through the lung microvasculature.

A serial study of splenic reticuloendothelial system Fc receptor functional activity in systemic lupus erythematosus

A serial study of reticuloendothelial system splenic Fc receptor function was undertaken in 13 patients with systemic lupus erythematosus (SLE). Fc receptor function was assessed by measuring the clearance half times of IgG-sensitized 51Cr-labeled autologous erythrocytes from the circulation. Prolonged clearance half times were initially detected in all patients, and the magnitude of the clearance defect was significantly correlated with disease activity (P less than 0.01, Spearman rank correlation) and immune complex levels (P less than 0.01). Clinical course and changes in receptor functional activity over time were found to be significantly correlated. Clearance half-times tended to return to normal in all 11 patients who clinically improved. The clearance half-time remained unchanged in 1 patient whose disease activity was stable, and it worsened in 1 patient whose illness flared. Levels of immune complexes also changed concordantly with clearance half-times and disease activity. These studies underscore the interrelationship between the presence of circulating immune complexes, defects in Fc receptor function that might lead to prolonged circulation of these complexes, and disease activity in SLE.

Clearance of sensitized erythrocytes in NZB/NZW mice. Effects of castration and sex hormone treatment

The clearance of particulate immune complexes consisting of erythrocytes sensitized with IgG or complement was investigated in (NZB x NZW)F1 (B/W) mice. Treatment of castrated B/W mice with androgen or estrogen was able to modulate this clearance. Young (3-month-old) male and female B/W mice cleared IgG-sensitized mouse erythrocytes rapidly, whereas older males (13 months) and females (7 months) showed a marked impairment in their ability to clear these cells. In addition, erythrocytes sensitized with complement in the absence of antibody were cleared within 5 min in young B/W mice. Older mice showed a greater and more rapid clearance rate of these cells. Castrated female B/W mice treated with androgen implants from three weeks of age showed improved clearance of IgG-sensitized erythrocytes at 7 months, whereas estrogen-treated male mice showed delayed clearance. These results suggest an age-dependent defect in the clearance of IgG-sensitized particles, perhaps due to diminished levels of serum complement and/or saturation of Fc receptors. In addition, there is an alteration in the clearance of complement-sensitized erythrocytes which may be related to changes in macrophage activity or enzyme inactivators of C3 and C4. The possible mechanisms responsible for the hormonal modulation of clearance are discussed in relation to the known ability of these hormones to influence autoimmune diseases.

Monocyte receptor function in patients with rheumatoid arthritis

Monocytes from patients with rheumatoid arthritis (RA), osteoarthritis (OA), and normal volunteers were studied for abnormalities of Fc and C3 receptor function. Monocytes from the majority of 22 patients with active RA showed enhanced E-rosette formation and Ea phagocytosis compared to monocytes from 20 normal volunteers and 10 OA patients, However, no significant differences in binding of EAC or uptake of iodinated aggregated gamma globulin were found among the 3 groups. Corticosteroid-treated RA patients exhibited significant depression of EA-rosette formation and phagocytosis. These results suggest that there is modulation of EA receptor function in monocytes from RA patients.

The effect of combination therapy (steroids, immunosuppressives, and plasmapheresis) on 5 mixed cryoglobulinemia patients with renal, neurologic, and vascular involvement

A prospective clinical study evaluated the effects of combined chemotherapy, steroids and plasmapheresis on 5 patients with mixed cryoglobulinemia with renal or neurologic and vasculitic manifestations. Treatment included prednisone (1mg/kg/day), chlorambucil (white blood cell count at greater than 3,000/mm3), and plasmapheresis (1 to 3 liters/week). There was healing of cutaneous ulcers (3/3), improvement in renal function (4/4), and diminution of purpura (2/2), but little improvement in peripheral neuropathy. Complications included leukopenia, perineal ulcers, and osteomyelitis.

Therapeutic plasmapheresis in systemic lupus erythematosus. Effect on immune complexes and antibodies to DNA

The effect of plasmapheresis in 8 patients with systemic lupus erythematosus (SLE) was investigated. Drug treatment was maintained at a constant level for at least 4 weeks before plasmapheresis. Levels of immune complexes were measured by a Raji cell radioimmunoassay, and by a solid-phase C1q-binding assay. Antibodies to ds-DNA and ss-DNA were measured by the Farr assay. In all cases, immune complexes and antibodies were lowered by plasmapheresis. In 5 patients, plasmapheresis was followed by a rapid rebound of complexes and antibody to pretreatment levels. In 3 in whom plasmapheresis was followed by treatment with cyclophosphamide for 1 month, a sustained immunochemical and clinical improvement followed, lasting in 2 cases for up to 3 years.

Reticuloendothelial system Fc receptor function and plasmapheresis in systemic lupus erythematosus: a preliminary report

Reticuloendothelial System (RES) Fc receptor-mediated immune clearance and levels of immune complexes were measured in patients with systemic lupus erythematosus undergoing plasmapheresis. RES clearance defects improved and disease manifestations and levels of circulating immune complexes decreased after plasmapheresis. Patients with initially abnormal reticuloendothelial system function, elevated levels of circulating immune complexes, and active acute illness appeared to respond to plasmapheresis. One patient with normal immune clearance, lacking measureable immune complexes, and manifesting chronic disease remained unchanged. Improvements seen following plasmapheresis were best maintained in patients receiving parenteral cyclophosphamide in the post-pheresis period. The correlation of clinical response, improved RES function, and decreased levels of immune complexes suggests the interaction of the latter two parameters in disease pathogenesis. Plasmapheresis has an important role as a research tool, and may be of clinical usefulness in a small number of patients with serious complications of systemic lupus erythematosus.

Mechanisms of neutrophil accumulation in the lungs of patients with idiopathic pulmonary fibrosis

Neutrophils are a characteristic feature of the alveolitis of idiopathic pulmonary fibrosis (IPF). a chronic disorder limited to lung. One mechanism by which neutrophils may be selectively attracted to lung and not other tissues is via the secretion of the neutrophil-specific chemotactic factor by alveolar macrophages. To evaluate the role of alveolar macrophages in modulating the migration of neutrophils to he lung in IPF, alveolar macrophages, obtained by bronchoalveolar lavage of patients with IPF, were evaluated for their ability to release a chemotactic factor for neutrophils. Unstimulated alveolar macrophages from normal individuals did not release the factor. In patients with IPF, there was a significant correlation between the proportions of neutrophils in lavage fluid and the release of a chemotactic factor for neutrophils by alveolar macrophages (p less than 0.001). The chemotactic factor released by IPF alveolar macrophages was of low molecular weight (400-600), at least partially lipid in nature, and preferentially attracted neutrophils compared with monocytes. Several lines of evidence suggested that immune complexes in the lung stimulated alveolar macrophages of patients with IPF to release the chemotactic factor. First, immune complexes stimulated normal macrophages to release the factor.Second, there was a significant correlation between the release of the chemotactic factor by IPF alveolar macrophages and the levels of immune complexes in bronchoalveolar lavage fluid. Third, bronchoalveolar lavage fluid containing immune complexes stimulated normal macrophages to release the factor. Fourth, IPF alveolar macrophages that released large amounts of the chemotactic factor had an apparent suppression of their immunoglobulin (Ig)G Fc receptor function, suggesting that immune complexes were bound to their surface. In contrast, the IgG Fc receptor function of IPF alveolar macrophages that released only small amounts of the factor was similar to that of normal macrophages. These studies suggest that neutrophils are attracted to the lung in patients with IPF by a potent chemotactic factor released by alveolar macrophages that have been stimulated, in vivo, via their IgG Fc receptor by immune complexes.

Influence of antigen on immune complex behavior in mice

To explore the possibility that the behavior of immune complexes can, under some circumstances, be directed by the antigen, we have studied the behavior of complexes of identical size made with the glycoproteins, orosomucoid (OR), and ceruloplasmin: or with their desialylated derivatives, asialo-orosomucoid (ASOR) and asialo-ceruloplasmin. Such desialylated proteins are rapidly removed from the circulation by a hepatic cell receptor for galactose, the sugar exposed upon removal of sialic acid. Mixtures of 125I-goat anti-ASOR with either ASOR or OR and mixtures of 125I-rabbit anti-OR with either ASOR or OR form complexes identically. The complexes were separated by density gradient centrifugation and injected intravenously into C3H mice. Blood clearance and hepatic uptake of the OR complexes and ASOR complexes were markedly different. T 1/2 for the goat OR complexes exceeded 300 min, whereas that for the ASOR complexes was 15 min. More detailed studies using rabbit complexes of various sizes revealed that light rabbit complexes behaved similarly to the goat complexes. The light rabbit OR complexes were cleared slowly, with only 18% found in the liver at 60 min, whereas the light rabbit ASOR complexes were cleared much more rapidly, with 62% found within the liver by 30 min. This rapid clearance was completely suppressed by a prior injection of a blocking dose of ASOR, which implies uptake by a galactose-mediated mechanism on hepatocytes. As the size of the rabbit complexes increased, so did the rate of Fc receptor-mediated clearance. Heavy rabbit OR complexes were cleared more rapidly than light OR complexes but not so rapidly as heavy ASOR complexes. The clearance and hepatic uptake of the heavy OR complexes were markedly suppressed by a prior injection of heat-aggregated gamma globulin, a known Fc receptor-blocking agent (45% hepatic uptake without and 6% with aggregated gamma globulin). The heavy rabbit ASOR complexes exhibited inhibition of blood clearance and hepatic uptake by both galactose receptor-blocking and Fc receptor-blocking agents. A blocking dose of ASOR reduced the hepatic uptake at 30 min from 75 to 49%, and heat-aggregated gamma globulin reduced it from 75 to 39%, which suggests that these heavy complexes were removed from the circulation by receptors both for the immunoglobulin and for the antigen. Cell separation studies and autoradiographs confirmed that those complexes cleared primarily by galactose-mediated mechanism were within hepatocytes, and those cleared by Fc receptors were within the nonparenchymal cells of the liver. It seems probable, therefore, the some antigen-antibody complexes may be removed from the circulation via receptors not only for immunoglobulin but also for antigen.

Detection of liver IgG Fc receptors using soluble immune complexes of peroxidase-antiperoxidase. II. Detection in liver tissue from mice with D-galactosamine-induced hepatitis

The presence of liver IgG Fc receptor sites was demonstrated in the liver tissue from C-57 black mice with D-Galactosamine (GalN)-induced hepatitis by the localization of soluble immune complexes of peroxidase-antiperoxidase (PAP). Cryostat sections of liver tissues were incubated with the complexes and the peroxidase activity was revealed histochemically. In the normal liver tissue, PAP were localized on the Kupffer cells, some of the sinusoidal walls, and the liver cell membrane mainly at the side of the sinusoid. Twenty-four hours after single administration of GalN (1,500 mg/kg body weight), positive PAP reaction was mainly observed on the membrane surface of infiltrating cells in the area of hepatocellular focal necrosis, and faintly observed on the degenerative hepatic cell membrane and the sinusoidal walls. After 48 hours, these features became more remarkable, especially at the sites with severe necrotic lesions. After 72 hours, the positive reaction on the regenerative hepatic cell membranes again became distinct. At the chronic stage 13 weeks after repeated administrations of GalN and Freund's complete adjuvant, a strong positive reaction was found on swollen and multiplied Kupffer cells, and a faint one found on the liver cell membrane, especially at the periphery of the lobules; moreover, many PAP-positive infiltrated cells were found in the area of piecemeal necrosis. The relationship between liver IgG Fc receptors and the severity of liver cell necrosis is discussed.

Detection of liver IgG Fc receptors using soluble immune complexes of peroxidase-antiperoxidase. I. Detection in liver tissue from patients with liver diseases

The presence of liver IgG Fc receptor sites was demonstrated in the liver tissue from 23 patients with liver diseases and 2 patients without liver lesions by the localization of soluble immune complexes of peroxidase-antiperoxidase (PAP). Cryostat sections of liver tissues were incubated with the complexes and the peroxidase activity was revealed histochemically. In the normal liver tissue, PAP were localized on the liver cell membrane, the Kupffer cells, and some of the sinusoidal walls. In acute hepatitis, a strongly positive reaction on swollen Kupffer cells was remarkable but positive reaction on the liver cell membrane was very weak. In chronic aggressive hepatitis, PAP were strongly positive on multiplied Kupffer cells and many PAP-positive infiltrated cells were observed at the area of piecemeal necrosis. However, the positive reaction on the liver cell membrane in patients with chronic aggressive hepatitis was generally fainter than in the normal cases without liver diseases. These results correlated well with the severity of liver cell necrosis. In chronic persistent hepatitis, the number of PAP-positive infiltrated cells in the portal area and positive Kupffer cells were fewer than in chronic aggressive hepatitis. Similar results were obtained with liver cirrhosis, and in particular, the liver cell membrane with regenerative nodules gave a positive reaction. A negative result was obtained by incubation with PAP-F(ab')2 alone. PAP reaction was significantly inhibited by pretreatment with aggregated human IgG, trypsin, and pronase but not with neuraminidase.

T gamma subset specificity of lymphocyte reactive factors in juvenile rheumatoid arthritis and systemic lupus erythematosus sera

Sera from 34 patients with juvenile rheumatoid arthritis (JRA), 31 patients with systemic lupus erythematosus (SLE), and 22 normal controls were studied for microcytotoxicity before and after clearing in the ultracentrifuge. Normal T cells as well as T gamma and non-T gamma subpopulations were used. Before ultracentrifugation all test sera showed apparent T gamma cell specificity in the microcytotoxicity assay where rabbit complement was added. JRA and SLE sera produced much higher proportions of cell killing than normal controls. Ultracentrifugal clearing resulted in marked diminution in microcytotoxicity of JRA and some SLE sera. However, a considerable proportion of lupus sera continued to show T cell subset cytotoxicity after ultracentrifugal clearing. No evidence for significant alteration of T gamma rosetting capacity was recorded when ultracentrifuge-cleared test sera were preincubated with T cells prior to T gamma EA rosette formation. Apparent T gamma cytotoxic specificity in some uncleared JRA and SLE sera may relate to high molecular weight materials (IgM and immune complexes) present in such samples, whereas in others it relates to lymphocyte reactive antibody with subset reactivity.

Altered immune complex-induced prostaglandin production in human and murine lupus

Monocytes were isolated by adherence from peripheral blood of normal controls and patients with systemic lupus erythematosus who were in the inactive and untreated phase of the disease. Peritoneal macrophages were isolated by adherence from NZB/W, BXSB and C57 control mice. These mononuclear phagocytes were cultured for 24 hours in the presence or absence of immune complexes (IC), after which prostaglandin E (PGE) levels were measured by RIA. Among the humans, normal monocytes responded to in vitro IC treatment with a 6.3-fold increase in PGE output and monocytes from SLE patients displayed only a 3-fold increase in PGE output. Baseline levels showed no difference. Circulating IC levels, as determined by the Raji cell assay, were highly elevated (greater than 6400 ug/ml) in all but one SLE patient. The murine lupus models compared to controls showed similar differences. C57Bl/nJ mice showed a significant increase of PGE production when stimulated with increasing amounts of IC. BXSB and NAB/W mice, however, showed no such increase. It is hypothesized that defective Fc receptor function on monocytes of patients with SLE prevent IC-induced production of normal amounts of PGE.

Opsonic requirements for intravascular clearance after splenectomy

We investigated the opsonic requirements for intravascular clearance of pneumococci in guinea pigs and of sensitized erythrocytes in human beings after splenectomy. The impaired clearance of injected pneumococci in splenectomized guinea pigs was corrected by immunization. This improvement in clearance was due to increased hepatic sequestration of organisms. There was a significant delay in antibody-mediated clearance of autologous erythrocytes sensitized with IgG (P < 0.001), although the rate of complement-mediated clearance in splenectomized patients was normal. A fourfold increase in sensitizing antibody resulted in a significant improvement in clearance that was due to increased hepatic sequestration (P < 0.005). One patient who had an intact spleen and who had previously received Thorotrast (thorium oxide) had impaired antibody-mediated clearance despite increased sensitization. These observations suggest that, after splenectomy the remaining macrophages of the reticuloendothelial system require increased amounts of antibody to mediate efficient intravascular clearance of opsonized particles.

Defective Fc-receptor functions associated with the HLA-B8/DRw3 haplotype: studies in patients with dermatitis herpetiformis and normal subjects

Dermatitis herpetiformis is associated with the HLA-B8/DRw3 haplotype in over 90 per cent of patients, and various percentages have been reported to have circulating immune complexes. Since removal of immune complexes from the circulation is thought to depend on the Fc-receptor function of tissue macrophages, we studied this function by measuring the clearance of IgG-sensitized autologous erythrocytes in 16 patients with dermatitis herpetiformis, in normal controls with the HLA-B8/DRw3 haplotype, and in randomly selected controls. All patients were HLA-B8 positive, and all of 12 patients tested were HLA-DRw3 positive. Erythrocyte clearance was reduced in eight of the 16 patients, but did not correlate with immune-complex levels. Four of eight controls with HLA-B8/DRw3 also had delayed Fc-receptor-mediated clearance as compared with normal controls. In addition, both patients and HLA-B8/DRw3-positive controls had decreased percentages and total numbers of T cells bearing Fc receptors for IgG. These findings indicate a functional Fc-receptor defect associated with the HLA-B8/DRw3 antigens.

Complement-mediated defect in clearance and sequestration of sensitized, autologous erythrocytes in rodent malaria

We investigated the ability of malaria-infected and normal mice to clear particulate immune complexes consisting of autologous erythrocytes sensitized with either IgG or complement. Normal mice rapidly clear autologous erythrocytes optimally sensitized with IgG and the liver plays a major role in their sequestration. Clearance of optimally sensitized erythrocytes is complement-dependent because cobra venom factor-treated, normal mice failed to clear these cells rapidly, unless they had been pre-treated with fresh mouse serum. In the initial phase of Plasmodium berghei infection, clearance of the optimally sensitized erythrocytes was markedly increased over that observed in normal mice. 2 wk after infection, however, clearance was minimal. This defect was most likely the consequence of the hypocomplementemia observed at this stage of infection since sensitized erythrocytes were removed rapidly from the blood if they had been coated with C3 in vitro before injection into malarial mice.The functional activity of the complement receptors of phagocytic cells was assayed in malarial mice by the injection of autologous erythrocytes coated with C3 and C4 in the absence of antibody. The complement-coated erythrocytes were rapidly removed from the blood, accumulated in the liver, and then gradually returned to the circulation. Similar patterns were observed in normal animals, but the degree of clearance was considerably higher in the malarial mice late in infection. It appears, therefore, that complement receptors remain functional throughout the infection. Erythrocytes suboptimally sensitized with IgG were cleared minimally by normal mice. This clearance was not complement-dependent and was mediated mainly by the spleen. During malaria, clearance of these particles was initially enhanced but later it was abolished.The association of hypocomplementemia with a major splenic defect in clearance late in malaria infection may explain the accumulation of immune complexes in pathological sites observed in this disease.

Modification of glomerular immune complex deposition in mice by activation of the reticuloendothelial system

To determine the effect of activation of the reticuloendothelial system on the localization of immune complexes in the kidney, a model of passive serum sickness nephritis in the mouse was used, with activation of the reticuloendothelial system with Corynebacterium parvum. Groups of mice, control and C. parvum-treated animals, were injected with BSA-125I-anti-BSA complexes containing 3 mg 125I-anti-BSA. Blood was obtained at 5 min, at 3 h, and at 12 h, when the animals were killed. Blood concentrations of BSA-125I-anti-BSA complexes were reduced in C. parvum-treated animals compared with controls. This appeared to be mediated by two effects, increased uptake of complexes in the liver and spleen, and enhanced degradation of immune complexes as measured by TCA-soluble radioactivity. In vitro studies using cultures of peritoneal macrophages also showed enhanced uptake of immune complexes. The amount of immune complexes deposited in the glomeruli of C. parvum-treated animals was reduced as determined by quantitation of radiolabeled material bound to isolated gomeruli and by immunofluorescence techniques. The results of the study emphasize the role of the reticuloendothelial system in the modulation of immune complex localization in the kidney and suggest a potential use of stimulants of the reticuloendothelial system in the therapy of immune complex nephritis.