Biomedical subjects
Publications and source records attributed to N J Struyf.
In two patients, women of 65 and 76 years old, colitis cystica profunda was diagnosed, a rare, benign disease of colon and rectum. In the first patient, radio-enteritis, in the second patient mucinous adenocarcinoma was diagnosed as well.
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Angioimmunoblastic lymphadenopathy is a rare lymphoproliferative disease with a poor prognosis. We saw a 24-year-old female patient with a fulminant evolution of an angioimmunoblastic lymphadenopathy, possibly a recurrence after a 10 years remission.
An experimental arthritis model in the rat was used to study the arthritogenic potential of complexed IgE. IgE aggregates were produced in vitro by cross linking monoclonal rat IgE by dimethyl suberimidate and were injected into the knee joints. Animals which had not been injected and animals injected with phosphate buffered saline served as controls. The concentration of histamine in tissues, diffusion into the joint of bovine serum albumin labelled with iodine-125 injected intravenously, and the histology of the joints were studied. There was a significant decrease in the concentration of histamine in synovial tissue 8 and 24 hours after the injection of the IgE aggregates. A decreased number of stainable mast cells were found 8, 24, and 48 hours after exposure. A moderate hyperplasia of the synovial lining layer was also noted. These results provide further evidence for the arthritogenic potential of complexed IgE, especially in the initiation of arthritis through activation of mast cells.
Neutrophil and monocyte activation by immune complexes containing IgE from serum and synovial fluid of patients with rheumatoid arthritis is reported. Activation of the inflammatory cells was measured by stimulation of the respiratory burst with production of intracellular hydrogen peroxide. Generation of hydrogen peroxide was analysed by a flow cytometric method, using the fluorochrome dichlorofluorescein. The technique was modified to allow measurement of cell activation of both neutrophils and monocytes by immune complexes in suspension. Ten of 14 polyethylene glycol precipitates from serum of patients with rheumatoid arthritis and 10/16 synovial fluids of these patients could activate neutrophils. A positive relation was found between the activation of neutrophils and the total concentration of immune complexes, the presence of IgG, and the presence of IgE in the immune complexes. Activation of monocytes was also shown, but to a lesser extent (8/14 rheumatoid serum samples and 8/16 rheumatoid synovial fluids activated monocytes). There was a weak correlation between the concentration of IgE immune complexes and the intensity of fluorescence measured in the monocytes.
The prevalence and composition of IgE-containing immune complexes in paired synovial fluid and serum of 42 patients with classical or definite rheumatoid arthritis were studied. IgE-containing immune complexes were found in 15/42 synovial fluids; 15 sera were also positive. The correlation between serum and synovial fluid complexed IgE levels was high (r = 0.77). The mean ratio of synovial fluid/serum levels was 1.96, i.e. significantly higher than 0.33, the synovial fluid/serum ratio for alpha-2-macroglobulin (molecular weight 820 kD), which was taken as high molecular weight control protein (p less than 0.0001). Apart from IgE in immune complex form, monomeric IgE was also significantly higher in synovial fluid compared to serum (ratio = 2.94). Other constituents which could be found in the immune complexes, i.e. anti-IgE antibodies, rheumatoid factors and anticollagen antibodies, were also higher in synovial fluid than predicted. Our results suggest intra-articular production of IgE-containing complexes in the synovial fluid, in addition to possible exudation of the complexes from the serum. These findings provide further evidence for the role of IgE-containing immune complexes in rheumatoid synovitis.
Natural killer (NK) cell activity and its stimulation by interferons (IFNs) and interleukin-2 (IL-2) are diminished in Sjögren's syndrome and systemic lupus erythematosus (SLE). Serum samples of these patients often contain circulating immune complexes, which may influence NK cell activity. Sixteen patients with Sjögren's syndrome (14/16 immune complex positive), 14 with SLE (9/14 immune complex positive), and 11 controls (immune complex negative) were studied. Mononuclear cells collected from a Percoll gradient were preincubated with recombinant IFN-alpha (rIFN-alpha) (100 U/ml), rIFN-gamma (1000 U/ml), rIL-2 (100 U/ml), or without cytokine. Natural killer cell activity was determined by incubating the mononuclear cells with carboxyfluorescein labelled K562 cells, and the percentage decrease of fluorescence was measured on an FACS Analyzer. In patients with Sjögren's syndrome and SLE NK cell activity and the numbers of cells expressing the NK cell associated antigens CD16 and Leu7 were diminished compared with the controls. Interleukin-2 stimulated NK cell activity significantly in comparison with the non-stimulated value in all studied groups, whereas IFN-gamma only stimulated NK cell activity in both patient groups and IFN-alpha only in patients with Sjögren's syndrome. There was no correlation between NK cell activity, with or without stimulation, and the immune complex concentrations. It is concluded that NK cell activity is decreased in Sjögren's syndrome and SLE and that it may be partially restored by IL-2 and IFN-gamma in both diseases, and by IFN-alpha in Sjögren's syndrome. The decrease of NK cell activity did not correlate with immune complex concentrations; on the other hand, decreased numbers of NK cells (CD16+ or Leu7+) and of cytokine concentrations might be important in the impaired NK cell activity in both diseases.
A decrease of natural killer cell activity (NKCA) during human pregnancy might contribute to the acceptance of the allogeneic fetus by the maternal host. The inhibition of NKCA might be due to serum factors derived from the trophoblast. We focused especially on the role of immune complexes, as it has already been described that these complexes depress NKCA and as they are found frequently in retroplacental serum. We have compared the influence of 19 paired retroplacental and peripheral blood sera on NKCA of normal donors. One peripheral and eight retroplacental sera contained immune complexes. Normal donor mononuclear cells were incubated with carboxyfluorescein-labeled K562 cells in the presence of retroplacental serum or peripheral serum. NKCA was measured on a FACS Analyzer. Ten of 19 retroplacental sera inhibited NKCA significantly in comparison to the corresponding peripheral serum (P = 0.003). There was no correlation between NKCA and the immune complex level. We conclude that, as compared to peripheral serum taken at delivery, there is a retroplacental serum-induced inhibition of NKCA, which is not correlated with the presence of immune complexes.
IgE-containing circulating immune complexes (IgE-CIC) were determined with a 2.5% PEG-precipitation assay in 98 patients with classical or definite rheumatoid arthritis (RA). Of the 45 IgE-CIC positive sera, only 4 had elevated total serum IgE. IgE-CIC positive patients had more active disease than patients without IgE-CIC, as determined by their more swollen joints and higher Ritchie indices (p less than 0.04 and 0.02, respectively). Apart from IgE, other immunoglobulin isotypes, rheumatoid factor (RF) of the IgG-, IgA- and IgM-classes, C3 and antinuclear antibodies could be demonstrated in the IgE-containing PEG-precipitates. IgE-RF could not be demonstrated in serum or in IgE-CIC. Anti-IgE of the IgM-class (IgMaIgE) were frequently found (28/45 patients) in the IgE-positive PEG-precipitates. All 14 patients positive for IgGaIgE in the IgE-CIC were also positive for IgMaIgE in the CIC. As in the serum, there was a good correlation in the CIC between the level of IgGaIgE and the level of IgMaIgE (r = 0.64). The correlation between the respective levels of IgGaIgE and IgMaIgE in serum and in CIC was high (r = 0.93 and 0.79, respectively). On the other hand, only 1 patient was positive for IgAaIgE in the IgE-CIC. We conclude that IgE and aIgE of the IgM- and IgG-classes are frequently present in the immune complex form in RA and that they are correlated with the clinical activity of arthritis.