Expression Of Complement Receptors Research Articles

Characterization of complement receptor type i and type 3 mrna expression on polymorphonuclear leucocytes (neutrophils) in gingival crevicular fluid from periodontitis-affected patients

A previous study has demonstrated that complement receptors on the surface of polymorphonuclear leucocytes (neutrophils) in gingival crevicular fluid significantly increased compared with those in autologous peripheral blood obtained from periodontitis-affected subjects. The present study attempted to determine the mRNA levels of complement receptor types 1 and 3 (CR1, CR3) on neutrophils in gingival crevicular fluid using reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization. Gingival crevicular fluid samples were obtained from 11 adult periodontitis patients by gingival crevicular washing, and venipunctured peripheral blood was used as a control. RT-PCR analysis was performed using the primer sets for CR1, CR3 and β-actin. Digoxigenin-labelled RNA probes were synthesized from RT-PCR products for in situ hybridization. Both CR1 and CR3 mRNA levels relative to β-actin were significantly lower in crevicular fluid neutrophils than in peripheral blood neutrophils (crevicular fluid-CR1: 32.75±22.93%, peripheral blood-CR1: 65.30±43.25%, p < 0.005; crevicular fluid-CR3: 9.09 ± 5.34%, peripheral blood-CR3: 30.14 ± 18.80%, p < 0.005). In in situ hybridization, a greater majority of neutrophils showed positive CR1 and CR3 mRNA expression, while only a few neutrophils showed positive signals in gingival crevicular fluid. Data in the present study suggest that increased expression of complement receptors on the neutrophil cell surface appears to be unrelated to de novo synthesis.

Mononuclear Cells in Corticosteroid-resistant Asthma

The airflow obstruction of the majority of patients with chronic and severe bronchial asthma will improve following treatment with glucocorticoids (OCs), but despite their clinical efficacy their mechanism of action in bronchial asthma is unknown. One way in which the mechanisms can be explored is to study a subgroup of patients in whom systemic or inhaled treatment with OCs, even when given in large doses, does not lead to any improve­ ment in airflow obstruction. The asthma in such patients is usu­ ally severe, and they are seriously disabled for long periods of time. We have defined corticosteroid-resistant (CR) asthma as an improvement in FEV, of less than 151170 after a 14-d course of 40 mg of prednisolone, whereas corticosteroid-sensitive (CS) asthma has been defined as an improvement of greater than 30% in FEV, after a similar course of prednisolone (1). CR asthma is associated with disease chronicity and a more frequent family history of asthma (2). Furthermore, there is increasing evidence for impaired in vitro and in vivo responsiveness of peripheral blood mononuclear cells (PBMCs) to the suppressive effects of glucocorticoids in these subjects. MONONUClEAR CELL DEFECTS IN CR ASTHMA In an ex vivo study, complement receptor expression on mono­ cytes from CS subjects was reduced after 1 wk of treatment with 20 mg oral prednisolone daily compared with cellsfrom untreated patients (3). The reduction in complement receptor expression induced by prednisolone was not observed in the monocytes of those patients exhibiting CR asthma. This work was extended by Poznansky and colleagues (4), who demonstrated that lO-8 to 109

Antibody response to a T-dependent antigen requires B cell expression of complement receptors.

Several lines of evidence indicate that antibody responses to T-dependent antigens require complement receptors expressed on either B lymphocytes or follicular dendritic cells. We have used RAG-2 deficient blastocyst complementation to create mice specifically lacking B cell complement receptors. Despite normal expression of complement receptor 1 (CR1[CD35]) and CR2 (CD21) on follicular dendritic cells, these mice have a profound defect in their capacity to mount a T-dependent antibody response. This is the first direct demonstration in vivo that B cell expression of complement receptors is required for a humoral immune response. This is the first direct demonstration in vivo that B cell expression of complement receptors is required for a humoral immune response. This suggests that CD21 and/or CD35 on B lymphocytes may be required for cellular activation, adsorptive endocytosis of antigen, recruitment to germinal centers, and/or protection from apoptosis during the humoral response to T-dependent antigens.

Moderate exercise triggers both priming and activation of neutrophil subpopulations.

We investigated how moderate exercise affects neutrophil microbicidal activity and whether exercise-induced responses are associated with changes in growth hormone (GH) secretion. Biological fluctuations were controlled for and GH secretion was manipulated by glucose ingestion. In eight men, 1 h of moderate exercise increased intracellular H2O2 generation in response to phorbol 12-myristate 13-acetate stimulation by threefold (P = 0.025) and complement receptor expression by 20% (P = 0.045). These responses were accompanied by a twofold increase in the plasma concentration of elastase, a marker of neutrophil activation in vivo. The plasma concentration of GH increased 10-fold after exercise, but this was reduced to 3-fold by glucose ingestion (P < 0.001), which also blunted elastase release (P < 0.001). Although the magnitude of H2O2 generation increased in proportion to the increase in plasma GH concentration, it declined progressively once this exceeded 20 ng/ml. The net response of neutrophils to exercise may represent a balance between the individual responses of subpopulations that are unaffected, primed, or fully activated by circulating mediators that respond to exercise and to dietary glucose intake.

Effect of porcine circovirus infection on porcine alveolar macrophage function

The effect of porcine circovirus (PCV) infection of porcine alveolar macrophage cultures on some of the functional properties of these cells are reported. PCV infection of alveolar macrophages did not affect their ability to phagocytose and kill complement-coated yeast cells or the expression of Fc or complement receptors. A transient increase in major histocompatibility complex (MHC) class I expression in PCV-infected cells was observed 4 days after infection and a decrease in the number of cells expressing MHC class II antigens was observed 8 days after infection. Infection of alveolar macrophages with PCV also resulted in a transient decrease in their ability to act as accessory cells in mitogen-induced lymphocyte proliferation of monocyte-depleted porcine peripheral blood mononuclear cells.

Subcellular Location of Neutrophil Opsonic Receptors Is Altered by Exogenous Reactive Oxygen Species

The effect of exposure of PMN to extracellular oxidants on the PMN oxidative burst on the subcellular location of CD64 (FcγRI), CD32w (FcγRII), CD16 (FcγRIII), CD35 (complement receptor 1), and CD11b/CD18 (complement receptor 5) was studied. Incubation of PMN with glucose/glucose oxidase resulted in an intracellular shift in Fcγ receptors from secretory vesicles to plasma membrane fractions while reducing complement receptor expression in plasma membrane fractions. Incubation of PMN with xanthine/xanthine oxidase resulted in an intracellular shift in Fcγ receptors from specific granules to secretory vesicles. Incubation of PMN with xanthine/xanthine oxidase resulted in an intracellular shift from secretory vesicles to plasma membrane fractions for CD35 and from secretory vesicles and specific granules to plasma membrane fractions for CD11b/CD18. The effects of glucose/glucose oxidase and xanthine/xanthine oxidase on receptor redistribution were blocked by catalase and catalase and superoxide dismutase, respectively. Cytoskeleton stabilization with phalloidin and Taxol blocked the effect of glucose/glucose oxidase and xanthine/xanthine oxidase on Fcγ and complement receptor relocation. Both H-7 and staurosporine abrogated the effect of glucose/glucose oxidase and xanthine/xanthine oxidase on Fcγ receptor relocation, while genistein abrogated the effect of glucose/glucose oxidase and xanthine/xanthine oxidase on complement receptor relocation. Increases in CD64, CD32w, CD16, CD35, and CD11b/CD18 expression associated with plasma membrane fractions corresponded to functional increases in monomeric IgG binding, E-IV.3, (sheep erythrocyte opsonized with monoclonal antibody IV.3 directed against CD32w) E–Con A, EC3b, and EC3bi rosetting. These studies indicate that exposure of PMN to extracellular oxidants does not occur as an isolated event but results in a coordinated subcellular relocation of opsonic receptors which corresponds to changes in PMN function.

Differential expression of complement receptors on human basophils and mast cells. Evidence for mast cell heterogeneity and CD88/C5aR expression on skin mast cells.

Abstract Complement-dependent activation of immune cells is regulated by cell surface membrane receptors. In this study, expression of complement receptors (CR) on human blood basophils (n = 11), tissue mast cells (lung, n = 7; skin, n = 10; uterus, n = 4; tonsil, n = 3; heart, n = 10), and on respective human cell lines (basophil line KU-812, mast cell line HMC-1) was analyzed by the use of mAbs and indirect immunofluorescence. Normal blood basophils and KU-812 cells were found to express C5aR (CD88), membrane cofactor protein (CD46), decay-accelerating factor (CD55), and membrane attack complex inhibitory factor (CD59), as well as the previously recognized CR1 (CD35), CR3 alpha (CD11b), CR4 alpha (CD11c), and CR3/4 beta (CD18). Mast cells from all organs as well as HMC-1 cells expressed CD46, CD55, and CD59, but not CD11b, CD21, or CD35. The C5aR (CD88) was detectable on skin mast cells, a subset (5 to 15%) of cardiac mast cells, and on HMC-1 cells, but not on lung, uterus, or tonsillar mast cells (&amp;lt; 5%). Moreover, double immunoperoxidase staining (tryptase vs C5aR/CD88) revealed in situ expression of C5aR on skin, but not lung mast cells. Recombinant human (rh) C5a, at 10(-10) to 10(-7) M, induced secretion of histamine from basophils (rhC5a, 10(-8) M: 53.4 +/- 3.1% vs control &amp;lt; 5%) and from skin mast cells (rhC5a, 10(-8) M: 25.8 +/- 16.1% vs control &amp;lt; 10% histamine release), but not from other mast cells (rhC5a or control: &amp;lt; 10%, p &amp;gt; 0.05). The rhC5a-induced secretion of histamine from basophils and skin mast cells was inhibited by S5/1, a blocking Ab against CD88 (basophils: 37.2% to 75.1%; skin mast cells: 39.2% to 83.9% inhibition, p &amp;lt; 0.05). Together, this study shows that a) basophils and mast cells express a different profile of complement receptors, b) C5a-dependent mediator release in skin mast cells and basophils is mediated via CD88, and c) mast cells constitute a heterogeneous lineage in terms of expression of the C5a binding site CD88.

Priming of human polymorphonuclear neutrophilic leukocytes by insulin-like growth factor I: increased phagocytic capacity, complement receptor expression, degranulation, and oxidative burst.

Insulin-like growth factor I (IGF-I) is a GH-dependent peptide regulating mammalian growth that seems to be of importance for the normal development and function of the immune system. Polymorphonuclear neutrophilic leukocytes (PMNLs) are terminally differentiated phagocytes essential for host defense, and in the present study, recombinant human IGF-I was shown to be a powerful primer of mature human PMNLs. IGF-I augmented the PMNL phagocytosis of both immunoglobulin G-opsonized Staphylococcus aureus and complement-opsonized Candida albicans. In addition, the growth factor increased PMNL complement receptor expression [complement receptors 1 (CD35) and 3 (CD11b)] and primed the cells to stronger f-met-leu-phe-induced degranulation of both specific and azurophilic granules [markers: CD11b, CD35 and CD67 (specific granules); CD63 (azurophilic granules)]. In contrast, IGF-I did not alter the PMNL surface expression of Fc gamma RI (CD64), Fc gamma RII (CDw32), or Fc gamma RIII (CD16). PMNLs exposed to IGF-I increased their f-met-leu-phe and phorbol myristate acetate-induced oxidative burst, as evaluated by hydrogen peroxide production, whereas IGF-I did not influence PMNL actin polymerization. The priming of PMNLs by IGF-I was dependent on time and concentration, and saturating amounts of a monoclonal antibody to the IGF-I receptor blocked the priming of PMNLs by this peptide. These experiments demonstrate that IGF-I can selectively stimulate mature PMNL functions, providing further evidence for the interaction between the immune and the endocrine systems.

Priming of human polymorphonuclear neutrophilic leukocytes by insulin- like growth factor I: increased phagocytic capacity, complement receptor expression, degranulation, and oxidative burst

Priming of human polymorphonuclear neutrophilic leukocytes by insulin- like growth factor I: increased phagocytic capacity, complement receptor expression, degranulation, and oxidative burst

Effect of BVD virus infection on alveolar macrophage functions

Alveolar macrophages (AM) were recovered by bronchoalveolar lavage from a group of eight calves at various times before and after inoculation with a cytopathic respiratory isolate of bovine viral diarrhoea virus (BVDV). A second group of four calves were given tissue culture medium as a control inoculum. Macrophages were also recovered from two additional, uninoculated calves, and were exposed to BVDV in vitro. Tests were carried out on the recovered macrophages to determine the effects of the virus on several functional properties. Immunofluorescence did not indicate the AM as being readily susceptible to this isolate of BVDV, although infection did occur. Fc receptor (FcR) and complement receptor (C3R) expression, phagocytosis and microbicidal activity and the production of neutrophil chemotactic factors were all significantly reduced in macrophages recovered from BVDV infected calves, compared with pre-inoculation control levels, whereas the control inoculated calves displayed significant increases in some of the functions. With macrophages exposed to the virus in vitro however, only FcR and C3R expression and phagocytic activity were significantly reduced. The results demonstrate that BVDV can reduce local immune defences in the lung, following infection by the respiratory route, and in conjunction with the other immunosuppressive properties of BVDV would favour a pre-disposing role for the virus in the pathogenesis of respiratory disease in calves.

Granulocyte colony‐stimulating factor administration modulates the surface expression of effector cell molecules on human monocytes

Granulocyte colony-stimulating factor (G-CSF) has been shown to stimulate human neutrophil functions, both in vitro and in vivo. We examined the effects of G-CSF administration on the surface expression of effector cell molecules on human neutrophils and monocytes. G-CSF (50 micrograms/m2/d) was administered subcutaneously to five healthy volunteers once a day for 7 d. Venous blood was obtained immediately before and after the completion of G-CSF administration and 1 week after the last G-CSF administration. The surface expression of complement receptors (CR), Fc receptors for IgG(FcR) and cellular adhesion molecules on human neutrophils and monocytes were determined by indirect immunofluorescence using flow cytometry and monoclonal antibodies. The expression of CR1, CR3, FcRI and FcRII on neutrophils increased significantly after G-CSF administration and then decreased after the last G-CSF administration. The expression of human leucocyte adhesion molecule-1 (LAM-1) on neutrophils reflected the above expression. On the other hand, the administration of G-CSF increased the expression of CR1, CR3, FcRI and FcRIII on monocytes. The expression of CR1, CR3 and FcRI on monocytes then decreased after the last G-CSF administration, whereas the expression of FcRIII remained at an increased level. These findings indicate that G-CSF administration modulates the expression of effector cell molecules on circulating monocytes as well as on neutrophils, resulting in enhanced defence against selected infections or in potentiation of the tumouricidal capacity of phagocytes in cancer patients.

Transforming growth factor beta modulates C3 and factor B biosynthesis and complement receptor 3 expression in cultured human monocytes.

Complement biosynthesis in monocytes is stimulated by different pathogens and modulated by a variety of cytokines, but little is known about the possible effect of transforming growth factor beta (TGF-beta) on this monocyte function. We therefore studied the effect of TGF-beta 1 and TGF-beta 2 on constitutive, lipopolysaccharide (LPS)- and Candida albicans-induced monocyte biosynthesis of complement components C3 and factor B. Under all three conditions, both forms of TGF-beta (20 ng/ml) induced a two- to fourfold increase in C3 concentration in monocyte supernatants harvested after 2 or 5 days of cell culture, an effect that was abrogated by cycloheximide. In contrast, constitutive and pathogen-induced production of factor B was suppressed by TGF-beta. The effects of TGF-beta on complement production were neutralized by a monoclonal anti-TGF-beta antibody. Moreover, TGF-beta suppressed the pathogen-induced release of granulocyte-macrophage colony-stimulating factor and down-regulated the expression of complement receptor 3 (CD11b/CD18), while the expression of CD11a/CD18, a related beta 2 integrin, was unaffected. These novel effects of TGF-beta emphasize the immunomodulatory significance of this cytokine.

Complement receptor expression on basophils and mast cells: Evidence for mast cell heterogeneity

Complement receptor expression on basophils and mast cells: Evidence for mast cell heterogeneity

Host cell components affect the sensitivity of HIV type 1 to complement-mediated virolysis.

An infection-competent, full-length HIV-1 clone (pNL4-3) was expressed in seven human cell lines and in peripheral blood mononuclear cells in order to assess the contribution of host cell components toward interaction of free virus with the complement system. HIV-1 expressed in the H9 cell line, which is frequently used for in vitro infection, was relatively susceptible to complement-mediated virolysis in the presence of both HIV antibody-positive patient serum and an anti-V3 monoclonal antibody. Expression of complement receptors 1, 2, and 3, complement control proteins membrane inhibitor of reactive lysis (MIRL, CD59) and decay-accelerating factor (DAF, CD55), and HLA-DR was assessed on host cells. There was an inverse relationship between the sensitivity of virus to complement and the amount of expression of MIRL and DAF on cells. HIV derived from the JY cell line and the mutant JY33 cell line, which is deficient in expression of phosphatidylinositol (PI)-linked proteins including MIRL and DAF, were also evaluated for complement-mediated virolysis. Virus expressed in the mutant cell line was more sensitive to antibody-independent as well as antibody-dependent complement-mediated virolysis than virus expressed in the wild-type cells. Direct demonstration of the presence of MIRL and DAF on the viral surface was obtained by showing that anti-MIRL or anti-DAF antibody induced complement-mediated virolysis. These experiments show that the host cell type can substantially influence the susceptibility of HIV to complement-mediated virolysis and suggest that PI-linked complement control proteins play an important role in this resistance.

Mycobacterial Heat‐Shock Protein 65 Induces Proinflammatory Cytokines but does not Activate Human Mononuclear Phagocytes

The 65 kDa heat-shock protein (Hsp65), a well-conserved and immunodominant antigen which elicits a cellular and humoral immune response, may play a role in host defence against invading microorganisms and autoimmune disorders. The aim of the present study was to assess the effects of Hsp65 on the functional activities of human mononuclear phagocytes in the absence of lymphocytes. Incubation with Hsp65 resulted in an enhanced release of TNF-alpha and IL-1 beta by human monocytes and monocyte-derived macrophages (MDM). The amount of cytokines released by these cells in response to Hsp65 was similar to that released in response to IFN-gamma together with LPS. Incubation with ovalbumin did not stimulate the release of these cytokines. In vitro stimulation of monocytes with Hsp65 enhanced the membrane expression of complement receptor III but did not influence either the expression of Fc gamma-receptor I and HLA class-II antigens or the release of reactive oxygen intermediates. Therefore, Hsp65-stimulated monocytes cannot be considered to be activated according to classical criteria. The release of the proinflammatory cytokines TNF-alpha and IL-1 beta by human mononuclear phagocytes in response to Hsp65 indicates that this protein can contribute to both host defence and tissue damage in inflammatory lesions characterized by an abundant expression of Hsp65.

Activation of polymorphonuclear neutrophilic granulocytes following burn injury: alteration of Fc-receptor and complement-receptor expression and of opsonophagocytosis.

Polymorphonuclear neutrophilic leukocytes (PMNLs) play a key role in host defense, and phagocyte dysfunction has been associated with increased susceptibility to infection in patients with thermal injury. We have used flow cytometric analysis (FCM) to longitudinally study PMNL expression of IgG Fc-receptor II (Fc gamma RII) and Fc-receptor III (Fc gamma RIII), as well as the complement receptors CR1 (receptor for C3b) and CR3 (receptor for C3bi) in 22 patients with large burns. Analyses of PMNL complement and immunoglobulin-mediated phagocytosis of Candida albicans were performed in parallel. Burn patient PMNL Fc gamma RIII expression was decreased to 58% of control values at admission, and remained low for the first 3 weeks. The expression of patient PMNL Fc gamma RII was not altered at admission or throughout the hospital stay. The CR1-dependent fluorescence was increased by 62% at admission, and reached a maximum at day 2, 138% greater than that of controls. The CR1 expression then gradually returned to normal at discharge. The PMNL CR3-dependent fluorescence showed an increase of 110% at admission and remained high during the first 3 weeks. The immunoglobulin-mediated phagocytosis was decreased by 12% at admission, whereas the lowest value was observed at day 10, with a reduction of 30% compared with controls. The patient PMNL complement-mediated phagocytosis of C. albicans was increased by about 160% at admission, and reached a maximum at day 2, before it gradually decreased to control levels at discharge. The expression of complement receptors correlated positively, whereas the expression of Fc gamma RIII correlated negatively, with total body surface area (TBSA) burn.(ABSTRACT TRUNCATED AT 250 WORDS)

Tissue-specific Fc gamma and complement receptor expression by alveolar macrophages determines relative importance of IgG and complement in promoting phagocytosis of Pseudomonas aeruginosa.

Because the expression of IgG Fc receptors and complement receptors on macrophages may vary in a tissue-specific manner, we used monoclonal antibodies and flow cytometry to define the expression and function of opsonin receptors on fresh normal and cystic fibrosis (CF) bronchoalveolar lavage (BAL) macrophages. Using flow cytometry to separately analyze individual types of cells, we then determined the relative contributions of IgG and complement to phagocytosis of Pseudomonas aeruginosa by fresh BAL cells, avoiding alterations in receptor expression due to in vitro purification or culturing techniques. Neither normal nor CF BAL macrophages express appreciable amounts of the complement receptors CR1, CR2, or CR3. These results were confirmed by immunohistochemical staining of fixed lung sections. BAL macrophages express a high-affinity IgG receptor, Fc gamma RI, that is not found on neutrophils (PMN). In contrast, chemoattractant-stimulated blood PMN express large amounts of CR1 and CR3 but do not express Fc gamma RI. These results correlate with phagocytosis assays, which show that phagocytosis by macrophages is enhanced by relatively low concentrations of IgG but that the addition of complement does not further increase their phagocytosis. In contrast, low concentrations of IgG alone do not promote phagocytosis by PMN, whereas addition of complement markedly enhances phagocytosis by PMN. These results may explain the previously reported sensitivity of macrophages rather than PMN to the "blocking" effects of anti-Pseudomonas antibodies from CF patients, and emphasize the pathologic significance of interference with IgG and complement mediated opsonization in the lung in CF.

HIV and Complement: Role of the Complement System in HIV Infection

HIV, in contrast to animal retroviruses, is not lysed by human serum but nevertheless the virus as well as virus-infected cells activate the complement system efficiently. HIV activates the classical pathway by binding C1q to the transmembrane protein gp41. On the surface of HIV-infected cells, both the alternative and the classical pathway are activated. Complement-treated HIV has an enhanced ability to infect cells carrying receptors for C3 fragments. By this mechanism complement can target the virus to certain cells, e.g. follicular dendritic cells. HIV-infected complement-coated cells can interact with complement receptor carrying cells and thereby spread the infection or cause the destruction of the infected cells. Due to direct or indirect effects of HIV the complement system is in an activated state and the cellular expression of complement receptors as well as regulatory molecules is modified in the blood of HIV-infected patients.

Ciliary neurotrophic factor (CNTF) promotes low-affinity nerve growth factor receptor and CD4 expression by rat CNS microglia

Ramified parenchymal microglia may provide immune surveillance in the nervous system and become activated in response to injury, showing increases in antigens found on macrophages, e.g. CD4 and MHCs. We investigated in adult rats the effects of a 2-week intraventricular infusion with ciliary neurotrophic factor (CNTF), a nervous system-associated cytokine, on microglia of the normal and injured corpus callosum. CNTF caused morphological changes, induced the expression of low-affinity nerve growth factor receptor and CD4 and increased the expression of complement receptor 3. Such changes were also observed after treatment of pure cultures of neonatal rat microglial cells with highly purified CNTF, suggesting a direct responsiveness to CNTF. Thus, endogenous astroglial and Schwann cell-derived CNTF may be an important component of the immune responses of the nervous system.

Expression of complement receptor 2 (CR2) on HTLY‐1‐infected lymphocytes and transformed cell lines

The expression of complement receptor 2 (CR2) has been demonstrated in established HTLV-1-transformed cell lines and in 12 studied de novo infected peripheral blood lymphocytes cultures, using 2 HTLV-1 sources. The simultaneous detection of CR2 and HTLV-1 antigens in both co-cultivated and supernatant-infected peripheral blood lymphocytes suggest that the increased CR2 expression is in tandem with the increasing HTLV-1 antigen expression. CR2 up-regulation seen during polyclonal activation is presumably in response to a viral protein, although a cellular factor has not been ruled out. Increasing CR2 expression during early infection suggests its possible involvement in selection or development of subsequent transformation events. Variable levels of CR2 in immortalized cell lines argue against its obligate expression of function in the maintenance of the transformed state. The expression of CR2 in cellular activation of T cells may be stage restricted. This study also expands the cellular distribution for CR2.