The influence of retinoic acid and retinoic acid derivatives on beta2 integrins and L-selectin expression in HL-60 cells in vitro.

A decreased expression of the beta2-integrin CD11b molecules on peripheral neutrophils from patients with pustular psoriasis occurred during treatment with retinoid compounds. Since this effect could not be mimicked in vitro with isolated peripheral neutrophils, the effect of retinoid compounds on cell differentiation was investigated. The promyelocytic cell line, HL60, was used to study what effect different retinoid compounds had on the cell surface expression of CD11b and L-selectin (CD62L) molecules, complement-mediated phagocytosis, adhesion and the oxidative burst. Retinoid-differentiated cells showed a significantly lower expression of CD11b and CD62L, and a decreased phagocytosis and oxidative burst compared to DMSO-differentiated HL60 cells or peripheral blood neutrophils. The diminished expression of beta2-integrins or L-selectin did not affect their adhesion to non-activated or lipopolysaccharide-activated endothelial cells in vitro but may however affect adhesion to vascular endothelium under shear forces during blood flow. These results suggest that retinoid treatment could affect several early steps in the inflammatory process.

Expression and function of beta 2 integrin CD11B/CD18 on leukocytes from patients with psoriasis.

The expression of beta 2 integrin CD11b on granulocytes and monocytes from patients with psoriasis vulgaris and pustular psoriasis was examined by flow cytometry. The amount of CD11b expressed on both granulocytes and monocytes was greater in 4 patients with pustular psoriasis than in 16 patients with psoriasis vulgaris. Its expression correlated with the development of pustules on the skin. No difference was seen between healthy blood donors and patients with active psoriasis vulgaris. Three patients with pustular psoriasis were followed during retinoid treatment. Granulocytes and monocytes showed a decrease in CD11b expression after administration of retinoids, in parallel with clearing of the skin. The adherence of granulocytes isolated from psoriasis patients was tested on cultured human umbilical vein endothelium. No significant difference in adherence was observed between control cells and cells from patients with active psoriasis vulgaris. These data indicate that the development of microabscesses in the dermis in psoriasis vulgaris is not related to enhanced beta 2 integrin function. The increased CD11b expression found in patients with pustular psoriasis may, however, serve as a triggering factor for pustule formation in pustular psoriasis.

Phenotypic alterations in circulating monocytes induced by open heart surgery using heparinized and nonheparinized cardiopulmonary bypass systems.

In this study of 31 patients with coronary bypass surgery, we used flow cytometry to compare heparin-coated and noncoated cardiopulmonary bypass systems on leukocyte activation. We found significant differences between the groups during bypass, with activation of the complement system, measured as elevated levels of C3a desArg, upregulation of granulocyte beta2 integrin (CD11b), and a loss of circulating monocytes when noncoated systems were used. In both groups an early increase in the monocyte cell surface CD62L expression was obvious while the percentage of human leukocyte antigen (HLA)-DR positive monocytes did not alter. The morning after the operation, leukocytosis was present, together with a highly significant reduction in the monocyte expression of CD11b and HLA-DR, indicating the recruitment to the peripheral blood of cells with altered phenotypes. This alteration in phenotype on potent inflammatory cells may be one part of the impaired function of the immunological system reported after major surgery.

A study of autoantibodies and circulating immune complexes in mercury-exposed chloralkali workers.

UNLABELLED: Inorganic mercury may cause immunologically mediated disease: e.g., glomerulonephritis, acrodynia, and contact allergy. Animal models have demonstrated the importance of genetic factors in determining susceptibility and resistance to autoimmunity, as well as the specific manifestation of the autoimmune response. Findings in groups of workers with occupational exposure to inorganic mercury have been inconsistent. OBJECTIVE: To investigate whether an immune response, caused by exposure to inorganic mercury (Hg), could be shown in occupationally exposed workers. METHODS: Immunoglobulin G (IgG), antinuclear autoantibodies, antibodies against thyroid, stomach or kidney antigens using indirect immunofluorescence, antibodies against glomerular basement membrane using ELISA, and circulating immune complexes in serum, and albumin in urine, were examined in Hg-exposed workers and controls. The two groups, 41 male chloralkali workers exposed to Hg vapour (mean exposure time 9 years) and 41 unexposed controls were age-matched and recruited from the same company. Hg concentrations in whole blood (B-Hg), plasma (P-Hg), and urine (U-Hg) were determined using cold vapor atomic spectrometry. DESIGN: Cross-sectional study. RESULTS: The mean B-Hg, P-Hg and U-Hg levels were 46 nmol/l, 37 nmol/l, and 27 micrograms/g creatinine in the exposed group, and 17 nmol/l, 6.9 nmol/l, and 3.4 micrograms/g creatinine in the referents. No statistically significant differences were found regarding IgG levels, urinary albumin excretion, prevalence of abnormal titers of autoantibodies or circulating immune complexes. There were no statistically significant associations between autoantibodies or immune complexes on the one hand and mercury exposure indices on the other. CONCLUSION: The results indicate that, if and when lasting autoimmune response occurs at the mercury exposure levels of the present study, it is uncommon. A small fraction of humans may, however, be susceptible to the development of autoimmunity, and there is also a possible "healthy worker" selection. Thus cross-sectional studies of moderate numbers of active workers will have low power to demonstrate autoimmune effects.

Labelling of leucocytes with technetium-99m exametazime causes in vitro upregulation of granulocyte CD11b without correlation to tissue uptake in vivo.

The aims of this study were to investigate whether labelling with technetium-99m exametazime alters the expression of adhesion molecule CD11b on granulocytes and monocytes, and to study whether the expression of CD11b on unlabelled or labelled cells correlates with uptake of the labelled cells in the inflamed bowel, in the lungs or in the reticuloendothelial system. Leucocytes were obtained from 25 patients with inflammatory bowel disease who underwent leucocyte scan. The cellular expression of CD11b was analysed using flow cytometry. Labelling with 99mTc-exametazime induced an increased surface expression of CD11b on granulocytes (P<0.01), but not on monocytes. The increase in CD11b expression on granulocytes was lower than the spontaneous mobilization that occurred at 37 degrees C and correlated neither with this, nor with N-formyl-methionyl-phenylalanine induced expression of the same receptor. Basal expression of CD11b on unlabelled granulocytes, but not on monocytes, correlated with bowel and lung uptake 45 min after reinjection of labelled cells, but not with uptake on later images. No correlation was found between the CD11b expression on labelled granulocytes or monocytes and scintigraphic uptake. Our findings show that labelling with 99mTc-exametazime increases the expression of adhesion protein CD11b on granulocytes. The increase in surface expression of CD11b does not correlate with the scintigraphic uptake of labelled cells in the bowel, in the lungs or in the reticuloendothelial system.

Endotoxemia and complement activation after severe burn injuries--effects on leukocytes, soluble selectins, and inflammatory cytokines.

In this study we followed the development of an inflammatory response in a group of patients the first week after a burn injury. We detected elevated plasma endotoxin levels, on at least one occasion, in 6 of 8 patients. No endotoxin was detected in the two patients with the lowest total burned surface area (< or = 30%). We found evidence of complement activation as increased C3a levels, in parallel with a production of inflammatory cytokines (TNF-alpha, IL-6). The TNF-alpha levels increased significantly during the observation period, while the IL-6 levels were elevated already at admission, and remained so. Elevated levels of soluble E-selectin were detected, indicating endothelial cell activation. Despite the inflammatory response and a loss of inflammatory cells during the first days of the monitoring period, we found no evidence of cellular activation measured as increased expression of beta 2 integrin CD11b, nor increased plasma levels of soluble L-selectin.

Upregulation of granulocyte CD11b (CR 3) after labelling with technetium-99m hexamethylpropylene amine oxime.

Today technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) is widely used for leucocyte scintigraphy, as 99mTc-HMPAO selectively labels granulocytes in mixed leucocyte suspensions. However, the influence of cell labelling on the expression of specific adhesion proteins has not been studied before. Therefore, we investigated five patients, four of whom had established Crohn's disease. We found that leucocyte labelling with 99mTc-HMPAO induces increased expression of the glucoprotein receptor CD11b on granulocytes, but it is not clear whether this upregulation affects the functional integrity of the granulocytes.

Transient endotoxemia during burn wound revision causes leukocyte beta 2 integrin up-regulation and cytokine release.

After severe burns, a wound revision is often done to remove devitalized tissue and minimize bacterial growth. After such revision, the patient may show signs of sepsis. In a group of burned patients we found a transient endotoxemia, and a subsequent leukocyte activation, monitored as increased expression of the beta 2-integrin CD11b, after such wound revision. In most patients we could detect elevated levels of plasma TNF-alpha before the operation, with no increases in these levels after the operation. Plasma levels of IL-6 were elevated in all patients and increased after the wound revision in all patients. They also had elevated plasma levels of soluble E-selectin, indicating systemic inflammation. The close relation between endotoxin levels and CD11b expression, and lack of evidence for additional production of TNF-alpha, suggests that up-regulation of the beta 2 adhesion protein during wound revision is mainly caused by endotoxin interaction with the leukocyte.

Hepatic immune complex elimination studied with FITC-labelled antigen.

Fluorescein isothiocyanate (FITC)-labelled model antigens (Ags) were used to form soluble IgG immune complexes (ICs) in vitro. The Ag and IC preparations were found to be excellent alternatives to isotope-tagged preparations for the study of plasma clearance after intravenous injection in rats. Ag and IC were eliminated from the blood at the same rate. By direct fluorescence microscopy the FITC-labelled IgG ICs could easily be detected in hepatic non-parenchymal liver cells 30 min after intravenous injection, whereas uncomplexed Ag was apparently taken up by the liver to a much lesser extent.

Elimination kinetics of circulating antigens and immune complexes. I. A simple multicompartment model for the analysis of blood elimination of intravenously injected antigens and immune complexes.

A multi-compartment model designed to analyse the blood elimination kinetics of intravenously injected radiolabelled antigens in experimental animals is presented. The model was fitted to experimental data on blood radioactivity levels at different times following intravenous injection of radiolabelled antigen. Numerical values were obtained for tissue association, degradation, and urinary recovery of degradation products. The model may prove useful as a test for reticuloendothelial function.

Anti-brush border antibodies (ABBA) in sera from patients with ulcerative proctocolitis and in sera with antibodies against Yersinia enterocolitica 0:3.

20 serum samples from patients with ulcerative proctocolitis (UC), and 20 serum samples with previously demonstrated IgG antibodies against Yersinia enterocolitica serotype 0:3 were analyzed with respect to the occurrence of anti-brush border antibodies (ABBA). 50% of the UC-sera and 20% of the anti-0:3 sera were ABBA-positive. Occurrence of ABBA did not apparently correlate to disease activity, or disease extension, or medication.