Search

This study investigated whether the high expression of adhesion molecules on enriched preparations of circulating dendritic cells (DCs) was an intrinsic property of the cells or whether it was a consequence of the procedure used to isolate them from blood. Expression of the β1, β2 integrins (CD11/CD18 family) and other adhesion molecules on DCs in whole blood was compared with that on isolated DCs. Dendritic cells were identified by flow cytometry as leucocytes that were positive for human leucocyte antigen (HLA)-DR, but negative for CD3, CD14, CD16, CD19 and CD56. In contrast to a minority of DCs in whole blood, the majority of isolated DCs expressed the β2 integrins and there were a greater number of cells beating CD44, CD54 and some of the β1 integrins (notably CD49b, CD49d, CD49e and CD29). An increase in the proportion of DCs bearing adhesion molecules was generally apparent at the isolation stage when mononuclear cells, which had been incubated overnight, were centrifuged on a metrizamide gradient to enrich for cells of low density. Inclusion of an inhibitor of protein glycosylation and exocytosis (brefeldin A) at all stages of separation partially prevented an increase in the percentage of DCs bearing CD18, C29 and C54 whereas the inclusion of cycloheximide (an inhibitor of polypeptide synthesis) interfered with increases in the percentage of cells bearing CD29 and CD54. Neither of these antagonists had an effect on the intensity of adhesion molecule expression. We suggest that some of the adhesion-dependent functions of isolated DCs are caused, in part, by an upregulation of surface adhesion molecules induced by the enrichment procedure. [ABSTRACT FROM AUTHOR]

This study assessed the distribution and structural features of plasma cells in rheumatoid synovial tissue. Plasma cells were found to be the predominant infiltrating mononuclear cells (mean 40%) in relation to lymphocytes and monocytes, and there was a direct relationship between their number in the infiltrates and the total number of mononuclear leucocytes (P = 0.007). Plasma cells were also seen in intimate contact with macrophages intermixed with synovial lining cells, and closely associated with small blood vessels. They often surrounded these blood vessels and sometimes were seen lying within the vessel walls themselves. Ultrastructural analysis revealed that many synovial plasma cells were considerably larger than plasma cells of a normal size and possessed a marked distension of the cisternae of rough endoplasmic reticulum. Furthermore, plasma cells in close proximity to blood vessels often appeared to be undergoing migration. These observations imply that in rheumatoid synovium, plasma cells are metabolically very active and occupy a pivotal position for the secretion of antibodies into both the vascular and the extravascular compartments. [ABSTRACT FROM AUTHOR]

Short-term (3 hr) incubation of whole blood with human recombinant cytokines induced rapid changes in the expression of monocyte but not of lymphocyte surface molecules. The percentage of monocytes bearing CD11b molecules was enhanced by tumour necrosis factor-beta (TNF-α), whilst that of CD11c was increased by both TNF-α and TNF-β. The mean fluorescence intensity (MFI) of monocyte CD11a was enhanced by interleukin-2 (IL-2), TNF-α and TNF-β, and that of CD11b. CD11c and CD18 was increased by IL-2, IL-4, TNF-α and TNF-β. The proportion of monocytes expressing HLA-DR antigens was not modified by the cytokines investigated, but its MFI was increased by IL-2, IL-4, TNF-α and TNF-β. In contrast, the percentage of monocytes bearing complement receptor 1 (CD35) was enhanced by IL-2, TNF-α and TNF-β but the MFI of this molecule was not modified by these cytokines. The highest up-regulation of CD18, HLA-DR and CD35 was observed with 100 U/ml of either IL-2. IL-4, TNF-α or TNF-β. Decreasing the concentration of all four cytokines from 100 to 10 and 1 U/ml diminished the levels of expression of all molecules, with the exception of CD35, which reached its maximum upon incubation with I U/ml of TNF-α. IL-1β, IL-6 or interferon-gamma (IFN-γ) did not modify the expression of any of the above monocyte surface determinants. Moreover, none of the lymphocyte surface molecules investigated was modified by 3-hr incubation of blood with cytokines. The demonstration that cytokines selectively and rapidly up-regulate integrins, complement receptor 1 and HLA-DR molecules, on monocytes but not on lymphocytes, suggests that similar mechanisms of mononuclear cell activation by cytokines may control the development and duration of the inflammatory process. [ABSTRACT FROM AUTHOR]

The percentage of human granulocytes expressing the integrins CD11b and CD11c as well as complement receptor 1 (CD35) was increased by short-term incubation of whole blood with interleukin-2 (IL-2), interleukin-4 (IL-4) and tumour necrosis factors alpha and beta (TNF-α and TNF-β). The mean fluorescence intensity of granulocyte CD18 was also increased by the above cytokines, whilst that of CD11b was only increased by TNF-β. Up-regulation of granulocyte CD18 expression was seen with 1 U/ml of IL-2, TNF-α or TNF-β, in contrast to the effect of IL-4 which was only observed with 100 U/ml. Similarly, enhanced expression of CD35 was induced by 1 U/ml of lL-2 or TNF-α but not by concentrations of IL-4 or TNF-β lower than 100 U/ml. Cytokine effects on the CD11/CD18 complex and CD35 molecules were not modified by cycloheximide, suggesting that their increased expression was not due simply to synthesis de novo. None of the granulocyte surface determinants investigated was altered upon short-term incubation of blood with either IL-1, IL-6 or interferon-gamma (IFN-γ). The demonstration in vitro that cytokines selectively up-regulate granulocyte integrins and complement receptor 1, suggests that similar mechanisms may be operating during the control of granulocyte-mediated inflammatory processes. [ABSTRACT FROM AUTHOR]

S-antigen, a potent retinal autoantigen involved in human inflammatory eye disease, has been chemically digested with cyanogen bromide to generate various peptide fragments. Cleavage of bovine S-antigen at methionyl residues generates seven major polypeptide fragments of apparent molecular weight 26,000, 22,000, 19,000, 18,000, 12,500, 8000 and 3000, respectively. Immunoblotting following SDS-polyacrylamide gel electrophoresis either with monoclonal antibodies known to be directed to two separate antigenic determinants on S-antigen or with various polyclonal antisera identified two peptide fragments of 26,000 and 18,000 MW. The extreme insolubility of the larger peptide fragments in aqueous or organic buffers makes the purification of the polypeptides by biochemical procedures difficult. However partial purification of the remaining soluble peptides by gel filtration in urea containing buffers made it possible to ascertain that the 18,000 MW peptide is an important constituent that carries a uveitogenic determinant of this autoantigen. [ABSTRACT FROM AUTHOR]

This paper describes the application of numerical methods to the arrangement of four leishmanial strains according to their reactivity and cross-reactivity in tests of parasite agglutination, indirect immunofluorescence and passive cutaneous anaphylaxis with antisera prepared by immunization or infection of rabbits, guinea-pigs and mice. Using corresponding pools of animal sera as test 'reagents' the antigenic reactivity of the four leishmanial strains (L. enriettii, L. tropica major, L. aethiopica and L. mexicana amazonensis) was scaled by reference to end point serum titres; and antigenic relationships between individual strain pairs were expressed as mean similarity coefficients, giving equal weight to the results of the different serological tests. Overall analysis of the results revealed that L. mexicana amazonensis and L. tropica major were the two most closely related strains, clustering with an overall similarity coefficient of 89 per cent, whereas coefficients of similarity between other strain combinations fell between 75 and 80 per cent. Although different sera had different discriminatory capacity for the leishmanial strains, two combinations of serum reagent and test system yielded relationships between the four strains that most closely approximated to the overall values. These were: (a) immunofluorescence tests with mouse antisera; and (b) agglutination tests with selected rabbit antisera. The results illustrate the use of a number of immunological parameters in relatingmicro organisms of a given genus, and reveal a serological classification of the four leishmanial strains at variance with their geographical origin. [ABSTRACT FROM AUTHOR]

Complement-fixing and precipitating antibodies to mitochondrial and lysosomal fractions of rat liver were induced in rabbits. The incubation of these subcellular fractions with ferritin-labelled antibody revealed localization of the antibody on mitochondria and lysosomes, but no specific morphological effect of antibody and complement. Incubation of the cell fractions with antibody and complement did not impair the efficiency of mitochondrial oxidative phosphorylation or affect the latency and sedimentation characteristics of lysosomal acid phosphatase. The results are discussed in relation to the action of antibody and complement on cells and to possible mechanisms of tissue damage in autoimmunity. [ABSTRACT FROM AUTHOR]

This communication describes the use of micro-electrophoresis in studying the changes in ascites tumour cells exposed to antibodies and complement. Treatment of the cells with rabbit antibody led to a change in electrophoretic mobility consistent with a surface adsorption of γ-globulin. The addition of complement led to a reduction in this electrophoretic effect of antibody. Treatment of the cells with neuraminidase, which produced a marked fall in their electrophoretic mobility, did not alter the effect of rabbit antibody and complement on the cells. Incubation with iso-antibody, in the presence or absence of complement, did not alter the mobility of the ascites cells measured at pH 7.0. The addition of 0.01 M calcium chloride to the electrophoresis medium produced a fall in mobility of the cells exposed to either antibody preparation in the presence of complement. Therefore, although iso-antibody and complement did not produce direct changes in cell mobility, changes in the cell surface could be detected by electrophoresis in the presence of calcium ions. The possibility is discussed that, during immune cytolysis, unmasking of phosphate groups of phospholipids might take place in the cell surface. [ABSTRACT FROM AUTHOR]

The injection of rat liver and rat brain in Freund's complete adjuvant into rabbits led to the production of complement fixing autoantibodies against rabbit tissue. The autoantibody response following the injection of rabbit liver and brain was much smaller. The autoantibody response to rat liver occurred even when Freund's incomplete adjuvant was used. The injection of rabbit liver in Freund's complete adjuvant into rabbits which had produced autoantibody after the injection of rat liver did not increase the level of autoantibody to rabbit liver. In most, but not all, rabbits the natural antibody found in the sera taken before immunization was destroyed by heating the sera at 65°. After immunization with rat liver in Freund's complete adjuvant the levels of serum antibody to rabbit liver stable at 56° rose by day 5; however, autoantibody stable at 65° was not detectable until between days 7 and 14. [ABSTRACT FROM AUTHOR]