Complement receptor 1 (CD35) on human reticulocytes: normal expression in systemic lupus erythematosus and HIV-infected patients.
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The low levels of complement receptor 1 (CR1) on erythrocytes in autoimmune diseases and AIDS may be due to accelerated loss in the circulation, or to a diminished expression of CR1 on the red cell lineage. Therefore, we analyzed the expression of CR1 on reticulocytes (R) vs erythrocytes (E). Healthy subjects had a significant higher CR1 number per cell on R (919 +/- 99 CR1/cell) than on E (279 +/- 30 CR1/cell, n = 23), which corresponded to a 3. 5- +/- 1.3-fold loss of CR1. This intravascular loss was confirmed by FACS analysis, which showed that all R expressed CR1, whereas a large fraction of E was negative. The systemic lupus erythematosus (SLE), HIV-infected, and cold hemolytic Ab disease (CHAD) patients had a CR1 number on R identical to the healthy subjects, contrasting with a lower CR1 on their E. The data indicated a significantly higher loss of CR1 in the three diseases, i.e., 7.0- +/- 3.8-, 6.1- +/- 2.9-, and 9.6- +/- 5.6-fold, respectively. The intravascular loss was best exemplified in a patient with factor I deficiency whose CR1 dropped from 520 CR1/R to 28 CR1/E, i.e., 18.6-fold loss. In one SLE patient and in the factor I-deficient patient, the FACS data were consistent with a loss of CR1 already on some R. In conclusion, CR1 is lost progressively from normal E during in vivo aging so that old E are almost devoid of CR1. The low CR1 of RBC in autoimmune diseases and HIV-infection is due to a loss occurring in the circulation by an active process that remains to be defined. (+info)
Serious hazards of transfusion (SHOT) initiative: analysis of the first two annual reports.
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OBJECTIVE: To receive and collate reports of death or major complications of transfusion of blood or components. DESIGN: Haematologists were invited confidentially to report deaths and major complications after blood transfusion during October 1996 to September 1998. SETTING: Hospitals in United Kingdom and Ireland. SUBJECTS: Patients who died or experienced serious complications, as defined below, associated with transfusion of red cells, platelets, fresh frozen plasma, or cryoprecipitate. MAIN OUTCOME MEASURES: Death, "wrong" blood transfused to patient, acute and delayed transfusion reactions, transfusion related acute lung injury, transfusion associated graft versus host disease, post-transfusion purpura, and infection transmitted by transfusion. Circumstances relating to these cases and relative frequency of complications. RESULTS: Over 24 months, 366 cases were reported, of which 191 (52%) were "wrong blood to patient" episodes. Analysis of these revealed multiple errors of identification, often beginning when blood was collected from the blood bank. There were 22 deaths from all causes, including three from ABO incompatibility. There were 12 infections: four bacterial (one fatal), seven viral, and one fatal case of malaria. During the second 12 months, 164/424 hospitals (39%) submitted a "nil to report" return. CONCLUSIONS: Transfusion is now extremely safe, but vigilance is needed to ensure correct identification of blood and patient. Staff education should include awareness of ABO incompatibility and bacterial contamination as causes of life threatening reactions to blood. (+info)
Modulation of renal disease in MRL/lpr mice genetically deficient in the alternative complement pathway factor B.
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In systemic lupus erythematosus, the renal deposition of complement-containing immune complexes initiates an inflammatory cascade resulting in glomerulonephritis. Activation of the classical complement pathway with deposition of C3 is pathogenic in lupus nephritis. Although the alternative complement pathway is activated in lupus nephritis, its role in disease pathogenesis is unknown. To determine the role of the alternative pathway in lupus nephritis, complement factor B-deficient mice were backcrossed to MRL/lpr mice. MRL/lpr mice develop a spontaneous lupus-like disease characterized by immune complex glomerulonephritis. We derived complement factor B wild-type (B+/+), homozygous knockout (B-/-), and heterozygous (B+/-) MRL/lpr mice. Compared with B+/- or B+/+ mice, MRL/lpr B-/- mice developed significantly less proteinuria, less glomerular IgG deposition, and decreased renal scores as well as lower IgG3 cryoglobulin production and vasculitis. Serum C3 levels were normal in the B-/- mice compared with significantly decreased levels in the other two groups. These results suggest that: 1) factor B plays an important role in the pathogenesis of glomerulonephritis and vasculitis in MRL/lpr mice; and 2) activation of the alternative pathway, either by the amplification loop or by IgA immune complexes, has a prominent effect on serum C3 levels in this lupus model. (+info)
Cytoplasmic inclusions in leukocytes. An unusual manifestation of cryoglobulinemia.
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Cryoglobulins are circulating immunoglobulins characterized by reversible, cold-induced precipitation. A variety of laboratory abnormalities, including hypocomplementemia, elevated erythrocyte sedimentation rate, rheumatoid factor activity, pseudoleukocytosis, and pseudothrombocytosis, are associated with cryoglobulinemia. Extracellular, faintly basophilic, amorphous deposits of cryoglobulins occasionally have been described in blood smears. In the present study, smears prepared from blood collected at room temperature from 6 patients with cryoglobulinemia exhibited neutrophil and, occasionally, monocyte inclusions containing clear, light pink, or faintly basophilic amorphous material. The inclusions were absent in smears from blood collected and maintained at 37 degrees C. Ultrastructural examination revealed that the material within the leukocyte inclusions was consistent with phagocytosed immunoglobulins. The identification of characteristic cytoplasmic inclusions in leukocytes may be an important clue in the early recognition of cryoglobulinemia. (+info)
Correlation between tumor induction and the large external transformation sensitive protein on the cell surface.
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The distribution on the cell surface of the large external LETS protein that is transformation sensitive of normal, transformed and tumorigenic cells was examined by immunofluorescent staining. A correlation was established between the expression of fibril-like LETS protein and the oncogenic capabilities of a series of adenovirus-transformed cell lines. In cells expressing a transformed phenotype in vitro, LETS protein is only detected in cell-cell contact areas, wheras in "untransformed" cells LETS protein is distributed over the cell surface. Transformed cells capable of inducing invasive tumors, and the cells of established tumor lines, have low or undetectable levels of LETS protein, as measured by this method. The results indicate that LETS protein has a role in cell-cell adhesion and that reduced expression of this protein at the cell surface is related to the oncogenic phenotype. This relationship has been established for experimentally induced and spontaneous tumors. (+info)
Complement fixation by rheumatoid factor.
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The capacity for fixation and activation of hemolytic complement by polyclonal IgM rheumatoid factors (RF) isolated from sera of patients with rheumatoid arthritis and monoclonal IgM-RF isolated from the cryoprecipitates of patients with IgM-IgG mixed cryoglobulinemia was examined. RF mixed with aggregated, reduced, and alkylated human IgG (Agg-R/A-IgG) in the fluid phase failed to significantly reduce the level of total hemolytic complement, CH50, or of individual complement components, C1, C2, C3, and C5. However, sheep erythrocytes (SRC) coated with Agg-R/A-IgG or with reduced and alkylated rabbit IgG anti-SRC antibody were hemolyzed by complement in the presence of polyclonal IgM-RF. Human and guinea pig complement worked equally well. The degree of hemolysis was in direct proportion to the hemagglutination titer of the RF against the same coated cells. Monoclonal IgM-RF, normal human IgM, and purified Waldenstrom macroglobulins without antiglobulin activity were all inert. Hemolysis of coated SRC by RF and complement was inhibited by prior treatment of the complement source with chelating agents, hydrazine, cobra venom factor, specific antisera to C1q, CR, C5, C6, or C8, or by heating at 56 degrees C for 30 min. Purified radiolabeled C4, C3, and C8 included in the complement source were bound to hemolysed SRC in direct proportion to the degree of hemolysis. These data indicate that polyclonal IgM-RF fix and activate complement via the classic pathway. The system described for assessing complement fixation by isolated RF is readily adaptable to use with whole human serum. (+info)
Cryofibrinogenaemia: a study of 49 patients.
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The purpose of this study was to characterize the clinical features and components of 30 patients with isolated cryofibrinogen (CF) versus those of 19 patients with combined CF and cryoglobulins (CG). Secondary forms of cryofibrinogenaemia associated with collagen disorders, infectious or malignant diseases, were significantly more frequent in patients with combined CF and CG than those with isolated CF (79 versus 47%, P = 0.02). Both groups of CF patients presented predominantly cutaneous symptoms (77% in isolated CF; 58% in combined CF + CG), and less frequently venous and/or arterial thrombosis (13% in isolated CF; 3% in combined CF + CG). Patients with idiopathic forms of CF, and particularly those without CG, suffered essentially from recurrent painful skin ulcers, mainly triggered by cold exposure. Patients with isolated CF had higher mean plasma concentrations of CF than those with combined CF + CG (1. 61 +/- 1.26 versus 0.82 +/- 1.18 g/l, respectively; P = 0.004), but there was no correlation between the CF plasma level and either the severity of symptoms or the sensitivity to cold. In patients with isolated CF, fibronectin was suggested (by precipitation analysis) to be a major component of the cryoprecipitate, whereas immunoglobulins were rarely present (in only three out of 30 patients). By contrast, in the majority of patients (78%) with combined CF and CG, the CF consisted mainly of immunoglobulins of the same class as those characterizing the associated CG. Analysis of the CG precipitate revealed the presence of fibronectin but not fibrinogen, alpha1-antitrypsin and alpha2-macroglobulin. In conclusion, isolated and combined cryofibrinogenaemia are associated with different clinical signs requiring different clinical management, but there is no evidence as yet for a causal role of the cryoprecipitates in the differences observed. (+info)
Specific concentration of polynucleotide immune complexes in the cryoprecipitates of patients with systemic lupus erythematosus.
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Although the association of cryoglobulinemia with hypocomplementemia and tissue injury in systemic lupus erythematosus is well recognized, composition of cryoprecipitates in terms of circulating antigens and antibodies in this disease is less clear. To clarify this question, cryoprecipitates from patients with SLE were examined with sensitive assay techniques for certain antipolynucleotide antibodies and DNA antigen. DNA antibodies were highly enriched relative to serum levels in the majority of cryoprecipitates. DNA antigen was also demonstrable. Antibody to ribonucleoprotein, although less frequently present, was similarly enriched in certain cryoprecipitates. In contrast, anti-double strand RNA, which was commonly detectable in relatively high titer in serum, was only minimally concentrated in a minority of cryoprecipitates. Absorption experiments using red blood cells heavily coated with polynucleotide antigen indicated that a major proportion of the IgG in certain cryoprecipitates was specific antibody. The data strongly suggest that the cryoprecipitates in systemic lupus erythematosus represent circulating immune complexes that are soluble at 37 degrees C and come out of solution in the cold. The marked concentration of immune complexes in the cryoglobulin offers a simple and direct method for determination of the nature of the complexes. The accumulated evidence obtained in the present study indicates that these complexes closely reflect, in their composition, the circulating immune complexes which are most significant pathogenetically in renal tissue injury. (+info)