PubMed Health⌕ Search

Biomedical subjects

M R Daha

Publications and source records attributed to M R Daha.

At least 271 records · Page 15Linked to original sources
PubMed1991

Interleukin-6 activity in paired samples of synovial fluid. Correlation of synovial fluid interleukin-6 levels with clinical and laboratory parameters of inflammation.

Paired synovial fluid (SF) samples obtained from the knees of 12 arthritis patients were studied to establish a relation between parameters of local inflammatory activity and SF interleukin-6 (IL-6) levels. Local disease activity was scored using joint temperature, swelling and pain as clinical parameters of inflammation. SF samples were assayed for laboratory parameters of inflammation such as leucocyte content, the percentage polymorphonuclear cells, the pH, and for immunoglobulin levels (IgG, IgM). SF IL-6 concentrations were determined using the B9-bioassay. Within individual patients the local activity of inflammation as measured using clinical parameters was found to be related to the local SF IL-6 level. When considering the total group of patients, a correlation (P less than 0.001) was found between the clinical parameters of local inflammation and the SF IL-6 levels. Furthermore, IL-6 levels were found to correlate with leucocyte counts (P less than 0.02), the percentage of polymorphonuclear cells (P less than 0.10), the pH value (P less than 0.01), but not with SF IgM and IgG concentrations.

Adult↗
PubMed1991

Lack of T cell oligoclonality in enzyme-digested synovial tissue and in synovial fluid in most patients with rheumatoid arthritis.

The dominant presence of specific T-cell populations in the rheumatoid joint as detected by Southern blot analysis of T cell receptor (TCR) gene rearrangements would indicate local antigen recognition and T cell proliferation. We therefore studied TCR beta chain gene rearrangements using a C beta 2 probe in paired samples of T cell populations from synovial tissue and peripheral blood (n = 6) as well as synovial fluid (n = 16) and peripheral blood (n = 18) of patients with rheumatoid arthritis (RA). Peripheral blood mononuclear cells from healthy donors (n = 7) served as a control. T cells were studied directly after isolation or after non-specific expansion with OKT3 monoclonal antibody (MoAb) and T cell growth factor (TCGF). DNA samples were digested with EcoRI and HindIII to detect rearrangements to C beta 1 and C beta 2, respectively. Extra bands were detected in all EcoRI-digested DNA samples prepared from both freshly isolated and non-specifically expanded T cell populations of patients and healthy donors, possibly representing 'common' (V-) D-J rearrangements. Dominant rearrangements were found in only two out of 16 synovial fluid T cell populations (one freshly isolated and one expanded) and not in peripheral blood or synovial tissue derived T cell populations. No extra bands were detected in HindIII-digested DNA samples. To investigate the effect of in vitro culture techniques on rearrangement patterns we studied DNA samples prepared from synovial tissue T cells obtained both by outgrowth from tissue with TCGF or by enzyme digestion and subsequent expansion either with TCGF or with OKT3 MoAb and TCGF. Whereas the latter T cell population yielded 'common' rearrangements, the former T cell populations yielded different dominant rearrangements. These data indicate that oligoclonality of the T cell populations in synovial tissue and synovial fluid of patients with RA is a rare event. The data also show the influence of in vitro culture techniques on the result of TCR gene rearrangement analysis.

Adult↗
PubMed1991

Kupffer cell depletion in vivo results in clearance of large-sized IgA aggregates in rats by liver endothelial cells.

We investigated the clearance kinetics and tissue distribution of different sized IgA in normal and macrophage-depleted rats. Rats were injected iv with liposomes containing dichloromethylene diphosphonate (DMDP). DMDP treatment resulted in complete depletion of liver macrophages 24-48 h after administration. Normal and macrophage depleted rats were injected intravenously with monomeric, dimeric, polymeric or aggregated polymeric IgA (AIgA) and assessed for blood clearance and tissue distribution. In normal rats, clearance of IgA was size dependent, i.e. a faster clearance with increasing size. No differences in clearance kinetics were observed of the different sized IgA between normal and DMDP-treated rats. TCA non-precipitable radioactivity, a measure for degradation of IgA, was found in the circulation of normal and DMDP-treated rats after AIgA administration. The liver was the main organ responsible for the clearance of IgA in normal and DMDP-treated rats. Immunofluorescence studies on liver biopsies indicated that AIgA was associated with Kupffer cells in normal rats. Electron microscopical studies revealed that the AIgA was internalized and located in vesicles in Kupffer cells. In DMDP-treated rats the AIgA was associated with endothelial cells and electron microscopy studies showed that this AIgA was taken up by endothelial cells. These data show that rat liver endothelial cells are able to bind, internalize and degrade AIgA in situations where Kupffer cells are absent, and that these cells may play an important role in the handling of AIgA and IgA-immune complexes.

Alkaloids↗
PubMed1991

Kupffer cell depletion in vivo results in preferential elimination of IgG aggregates and immune complexes via specific Fc receptors on rat liver endothelial cells.

In the present study we have investigated the clearance kinetics and tissue distribution of monomeric (m) IgG and soluble aggregates of IgG (AIgG) and immune complexes (IC) in normal and Kupffer cell (KC) depleted rats. In normal rats, clearance of mIgG occurred in a biphasic manner with a first half-life (T1/2) (T1) of 36.3 +/- 6.3 min and a second T1/2 (T2) of 168.4 +/- 4.7 min. AIgG composed of 20-27 IgG molecules per aggregate were cleared significantly faster than mIgG with a T1 of 2.5 +/- 0.1 min and a T2 of 32.5 +/- 5.6 min. KC depletion did not have a significant effect on the clearance rate of mIgG (T1: 33.4 +/- 8.9 min; T2; 159.5 +/- 12.5 min), while clearance of AIgG was delayed significantly with T1 4.8 +/- 0.7 min and T2 41.2 +/- 3.2 min. Eight minutes after injection, 77% of AIgG was found in the liver in normal rats while 62% was found in the liver of KC-depleted rats. Double immunofluorescence studies indicated that AIgG in the liver was associated with KC and endothelial cells (EC) in normal rats. In KC-depleted rats, AIgG was strongly associated with EC. A similar staining pattern was observed when IgG-immune IC were administered. The clearance of AIgG in KC-depleted rats was inhibited fully by pre-administration of high concentrations of IgG but not by pretreatment with IgA. asialofetuin (ASFe) or ovalbumin (OVA). Aggregated F(ab')2IgG was cleared with a comparable rate to mIgG from the circulation, again suggesting Fc gamma receptor-mediated elimination of AIgG by EC. There was a reduced degradation of AIgG in rats depleted of KC as compared with normal rats. These data suggest binding and degradation of AIgG by EC in vivo.

Animals↗
PubMed1991

Characterization of anti-endothelial cell antibodies in systemic lupus erythematosus (SLE).

IgG anti-endothelial antibodies (AEA), as measured by ELISA or immunoblotting technique could be detected in serum samples of 56 out of 64 patients with SLE (88%) and mainly occurred in monomeric form. AEA were not cell specific, because the binding reactivity was absorbed partially by both fibroblasts and peripheral blood mononuclear cells. No correlation was found between the presence of AEA and anti-nuclear antibodies. Immunoblotting revealed reactivity of AEA against endothelial antigens ranging in size from 15 to 200 kD. AEA titres were significantly higher in patients with joint or skin abnormalities, compared with patients without these abnormalities. A significant correlation was found between nephritis in SLE and the presence of AEA reactivity against endothelial membrane antigens of 38, 41 and 150 kD. These data show that the pattern of AEA reactivity in serum of SLE patients is heterogeneous, and suggest that AEA against a limited number of antigens may be involved in the pathogenesis of nephritis in SLE.

Antibodies, Anti-Idiotypic↗
PubMed1991

Deposition of IgA is associated with macrophage influx in the kidney of rats.

In the present study we treated rats with N-nitrosodimethylamine (DMN) or D-galactosamine (GALN) to achieve increased circulating IgA levels in rats. GALN-treated rats showed a six-fold increase in serum IgA levels after the first intraperitoneal (i.p.) injection, whereas a 10-fold increase after a second i.p. injection of GALN was seen. DMN-treated rats showed a three-fold increase in serum IgA levels. No differences were observed in IgG and IgM levels between treated and non-treated rats. Sequential renal biopsies analysed by immunofluroescence exhibited mesangial deposits of IgA with different intensities of C3 deposition. Rats treated with GALN showed more IgA deposition in the kidney than DMN-treated rats. The IgA deposition together with C3 was more prominent in rats treated with GALN than in rats treated with DMN. The deposition of C3 together with IgA was associated with an influx of monocytes as detected by ED-1, an antibody directed against a rat monocyte marker. These studies provide evidence that an increase in serum IgA levels is associated with deposition of IgA in the kidney and that IgA has an inflammatory potential.

Animals↗
PubMed1991

Uptake and degradation of soluble aggregates of IgG by monocytes of patients with rheumatoid arthritis: relation to disease activity.

Monocytes from patients with rheumatoid arthritis (RA) and rheumatoid vasculitis have a diminished ability to degrade soluble complexes of aggregated IgG in the absence (mediated by Fc receptors) as well as in the presence of complement (C) (mediated by (Fc + C) receptors). To investigate whether a relation exists between the receptor mediated degradation of aggregated IgG by adherent monocytes and disease activity a longitudinal study was performed in 79 patients with RA and rheumatoid vasculitis over a period of 16 months. Adherent monocytes were incubated in vitro with 125I labelled IgG aggregates of restricted size in the absence or presence of fresh serum and the percentage of catabolised IgG aggregates was measured. Cross sectionally the degradation of aggregated IgG by monocytes, mediated by Fc and (Fc + C) receptors, correlated significantly with disease activity as scored by the Ritchie articular index, the presence of extra-articular features, and circulating immune complexes. A high number of Fc receptors on monocytes correlated with diminished degradation, whereas high numbers of complement receptors 1 and 3 correlated with enhanced degradation of aggregated IgG mediated by both Fc and (Fc + C) receptors. The degradation of aggregated IgG by monocytes did not correlate with disease activity in individual patients followed up longitudinally. When patient groups were formed according to the results of longitudinal studies, however, degradation of aggregated IgG mediated by Fc and (Fc + C) receptors was significantly decreased in patients with rheumatoid vasculitis and in patients with active RA in comparison with patients with inactive RA and healthy controls. Patients with active RA and rheumatoid vasculitis also expressed significantly more Fc receptors and less complement receptors on the monocytes than patients with inactive RA. Drug treatment did not correlate with receptor expression or the degradation of aggregated IgG by monocytes either in cross sectional or longitudinal studies. It is concluded that in RA disease activity is related to receptor expression and the degradation of soluble immune aggregates by monocytes.

Adult↗
PubMed1991

Immunoglobulin A: interaction with complement, phagocytic cells and endothelial cells.

Deposits of IgA together with complement (C) in different organs support the hypothesis that IgA can trigger inflammatory mechanisms. Some inflammatory mechanisms may be caused by activation of C and phagocytic cells. Therefore, it is essential to understand the interaction of IgA with C and phagocytic cells. Studies will be described demonstrating that polymeric human serum IgA is able to activate the alternative pathway of C and that the activating principle is located in the intact F(ab')2 portion of the molecule. Activation of C is dependent on the molecular composition of IgA, as derived from results obtained with rat monoclonal IgA antibodies. Furthermore, it is demonstrated that polymeric IgA (pIgA) and dimeric IgA (dIgA) are potent activators of C in a homologous rat model, whereas monomeric IgA (mIgA) has a very poor C-activating potential. The interaction of IgA with phagocytic cells induces phagocytosis and release of H2O2 by granulocytes, which may contribute to tissue damage. Little is known about the clearance mechanism of IgA. It is shown in this report that Kupffer cells and C play an important role in the clearance of IgA immune complexes (IC). Clearance of large-sized IgA IC occurs via different receptors present on Kupffer cells. Finally, a new aspect will be described: the interaction of IgA with endothelial cells. Rat liver endothelial cells are able to eliminate IgA IC from the circulation via specific receptors when no Kupffer cells are present. These observations may contribute to our knowledge on diseases such as IgA nephropathy and Henoch-Schönlein purpura. The studies summarized and presented here illustrate the inflammatory potential of IgA.

Animals↗
PubMed1991

Interleukin 2 mediates stimulation of complement C3 biosynthesis in human proximal tubular epithelial cells.

Previous reports have suggested the production of complement components C4, C2, and factor B by renal tissue. However, the cells involved in production of complement have not been identified. In this study metabolic labeling experiments demonstrated that human proximal tubular epithelial cells (PTEC) synthesize a 180-kD precursor of C3 that is secreted after proteolytic cleavage into a disulphide linked two-chain molecule as found in plasma. C3 present in culture supernatants of PTEC was functionally active, however, during the culture period there was a partial inactivation of the C3 molecule as assessed by hemolytic titration. Recombinant IL-2 enhances the rate of C3 synthesis in a dose-dependent manner reaching maximal stimulation at doses of 200-400 U/ml IL-2. Northern blot analysis demonstrated a 5.2-kb C3 mRNA species present in PTEC that was increased within 24 h of IL-2 treatment. IL-2-induced enhancement of C3 production by PTEC could be neutralized with specific antibodies to IL-2. This study demonstrates that C3 synthesis in PTEC is upregulated by IL-2, the major cytokine produced by activated T cells.

Animals↗
PubMed1991

Effect of monomeric immunoglobulin G (IgG) on the clearance of soluble aggregates of IgG in man.

Serum concentrations of IgG may influence Fc receptor-mediated clearance of immune complexes. For instance, when 123I-labeled aggregates of human IgG (123I-AIgG), used as a model for soluble immune complexes, are administered to patients with systemic lupus erythematosus (SLE), there is an inverse correlation between the serum concentrations of IgG and the clearance and volume of distribution in steady state (Vss) of 123I-AIgG. To answer the question whether IgG has a direct effect on the clearance of immune complexes, we measured the elimination of 123I-AIgG in eight patients with hypogammaglobulinemia, before and after substitution with intravenous gammaglobulin (IVIG). As expected, raising IgG concentrations in these patients (by 6 g/l) caused a significant decrease of the Vss of 123I-AIgG. However, clearance of 123I-AIgG remained unchanged by IVIG. Thus, the results of this study offer no experimental evidence that raising concentrations of IgG influences the clearance of soluble immune complexes.

Adult↗
PubMed1991

On the origin of the FcRIII (CD16)-containing vesicle population in human neutrophil granulocytes.

Human blood neutrophils bear two types of Fc receptors that recognize the Fc portion of immunoglobulin G: FcRII and FcRIII. In earlier studies we found that neutrophils not only express FcRIII on their plasma membrane but also contain a large population of FcRIII-containing vesicles mainly located in the juxtanuclear area. To find out whether these vesicles derive from the plasma membrane, we used electron microscopic techniques to study compartments involved in ligand-independent endocytosis in human neutrophil granulocytes. The endocytic compartments were labeled with BSA-gold. This marker entered the cell through non-coated invaginations of the plasma membrane as well as via coated pits. After internalization, BSA-gold was present in numerous electron-lucent vesicles in the juxtanuclear area and in the trans-Golgi reticulum, endosomes, and lysosome-like structures. FcRIII also occurred in the BSA-gold-containing electron-lucent vesicles in the juxtanuclear area, as shown by postembedding immunocytochemical labeling of FcRIII in cells already containing BSA-gold. Quantification showed that 29% of all FcRIII-containing vesicles also bear BSA-gold while the remaining 71% contain only the receptor. In sum, our findings show that one third of the FcRIII-containing electron-lucent vesicles in neutrophil granulocytes derive from the plasma membrane and are involved in ligand-independent endocytosis of FcRIII. The majority of these vesicles, however, are not of an endocytic origin and might constitute an "internal pool" of receptors in these cells.

Antibodies, Monoclonal↗
PubMed1991

Systemic effects of collagen-impregnated aortoiliac Dacron vascular prostheses on platelet activation and fibrin formation.

To minimize intraoperative blood loss a watertight knitted Dacron aortoiliac prosthesis has been developed by impregnation with bovine collagen. A potential disadvantage is that collagen may be associated with an increase in thrombus formation. We conducted a prospective randomized trial to study the systemic effects of collagen-impregnated prostheses and of aortoiliac operation as such on the coagulation mechanism during the first 10 days after operation. Forty-one patients randomly received either a collagen-impregnated (n = 20) or a nonimpregnated prosthesis (n = 21). Twelve patients who underwent cholecystectomies served as controls. Three markers of the coagulation mechanism were monitored: beta-thromboglobulin, fibrinopeptide A, and fibrin/fibrinogen degradation products. We found no significant differences in median beta-thromboglobulin, fibrinopeptide A, and fibrin/fibrinogen degradation product levels between patients in the collagen-impregnated prosthesis group and patients in the nonimpregnated prosthesis group. This indicates that collagen does not stimulate the coagulation cascade any more than conventional Dacron protheses do. In a comparison of patients who underwent aortoiliac reconstruction and patients who underwent cholecystectomies, the results indicated a significant increased platelet activation and fibrin metabolism in aortoiliac reconstruction group compared with the control group. Finally, we observed a significantly higher preoperative fibrin metabolism in patients with vascular disease than in control subjects. This difference is attributable to the high preoperative fibrin/fibrinogen degradation product values in patients with aortic aneurysms.

Adult↗
PubMed1990

Evaluation of the efficiency of two IgA immune complex assays.

Two IgA immune complex assays, namely the anti-IgA inhibition of binding assay (a-IgA-InhBA) and the IgA polyethylene glycol assay (IgA-PEG assay) were evaluated using IgA aggregates (AIgA) of well defined sizes. AIgA was prepared by heat treatment. After ultracentrifugation the size of AIgA was found to be in a range between 7 S and 64 S. Five AIgA pools (greater than 64 S, 44-64 S, 24-43 S, 20-24 S and 9-19 S) and a pool of monomeric IgA were prepared to test the efficiency of the two assays. The IgA-PEG assay exclusively detected very large sized AIgA (greater than 64 S), whereas the a-IgA-InhBA detected also AIgA of intermediate size (9-19 S). The sensitivity of the latter assay was found to be size dependent. After ultracentrifugation of serum samples from patients with IgA nephropathy, IgA of large and intermediate macromolecular size was detected. It is concluded that the a-IgA-InhBA is useful for the detection of circulating IgA-containing immune complexes in IgA nephropathy.

Antigen-Antibody Complex↗
PubMed1990

Differential regulation of complement factor H and C3 production in human umbilical vein endothelial cells by IFN-gamma and IL-1.

Human umbilical vein endothelial cells (HUVEC) synthesize and secrete C component factors H and C3. Addition of T cell growth factor to HUVEC enhanced factor H production, and caused a profound increase in C3 production. In the present study, investigations were initiated to characterize the effects of purified rIL-1 and rIFN-gamma on the production of factor H and C3 at the protein and mRNA level. IFN-gamma enhanced factor H production in a dose-dependent fashion and a two-fold increase was observed with an optimal dose of 200 U/ml, whereas IFN-gamma had no effect on C3 production. IL-1 inhibited factor H secretion, but the production of C3 was increased 10-fold at an optimal dose of 500 pg/ml of IL-1. Kinetic experiments demonstrated that addition of IL-1 to HUVEC resulted in an induction of C3 production after more than 24 h, whereas IFN-gamma already had a significant effect on factor H production after 8 h of culture. IL-1 in combination with IFN-gamma had a synergistic effect on C3 production. The effects of IL-1 and IFN-gamma on factor H and C3 production by HUVEC could be blocked by using neutralizing amounts of antibodies specific for these cytokines. Northern blot analysis showed that factor H mRNA expression was enhanced in IFN-gamma-treated HUVEC and C3 mRNA was induced in IL-1-treated HUVEC, indicating that the observed increase of factor H and C3 probably is controlled by enhancement of transcription or stability of the transcript.

Blotting, Northern↗
PubMed1990

Enhanced Ig production by human peripheral lymphocytes induced by aggregated C1q.

Because B cells express receptors for C1q, we have investigated the role of C1q in the stimulation of B cells. When B cells were cultured in the presence of C1q that had been frozen, T cells, and suboptimal concentrations of PWM, there was a dose-dependent enhancement of IgM, IgG, and IgA by the B cells. No significant enhancement of Ig production by B cells was seen in the absence of T cells or PWM. The contribution of T cells or PWM could be replaced by supernatants of PMA and Con A-activated PBMC (T cell growth factor). C1q that had been frozen, in contrast with freshly isolated C1q, was at least 3 times more active in enhancement of the production of Ig by B cells in culture in the presence of suboptimal concentrations of T cell growth factor. The capability of C1q to stimulate B cells could be ascribed to aggregates of C1q. Monomeric C1q was only marginally active to stimulate B cell Ig production, whereas dimeric and tetrameric C1q were able to enhance Ig production by B cells in relation to their size. Furthermore, aggregation of C1q on soluble aggregates of rabbit IgM also increased its potential to enhance B cell Ig production. The interaction of C1q with the B cells occurs via the collagenous tail of C1q, as suggested by inhibition experiments with purified collagenous tails and globular heads of C1q. These results indicate that triggering of C1qR on B cells positively regulates Ig production in vitro.

Antibody Formation↗
PubMed1990

Intracellular localization and de novo synthesis of FcRIII in human neutrophil granulocytes.

Immunoelectron microscopic studies in human neutrophils showed that FcRIII was present on the plasma membrane, in the Golgi complex, and in many small vesicles (120 to 180 nm). FcRIII was not found in specific or azurophilic granules as shown by immunogold double-labeling experiments, visualizing both FcRIII and either lactoferrin (a marker of specific granules) or myeloperoxidase (a marker for azurophilic granules). Because the occurrence of FcRIII in the Golgi complex suggested that biosynthesis of this receptor occurs in these cells, metabolic labeling experiments were performed. Immunoprecipitation of FcRIII from NP-40 lysates of cells labeled with 35S-methionine showed a diffuse 50- to 70-Kd band corresponding with the band noted after immunoprecipitation of FcRIII from surface iodinated cells. These findings show that de novo synthesis of FcRIII occurs in neutrophils and suggest that at least some of the small vesicles containing FcRIII derive from the Golgi complex and thus are involved in transport of newly synthesized FcRIII to the plasma membrane.

Antigens, Differentiation↗
PubMed1990

IgG and IgA antibodies to the collagen-like region of C1q in rheumatoid vasculitis.

We investigated the presence of IgG and IgA antibodies to C1q in serum samples from 80 patients with rheumatoid arthritis (RA), 31 patients with rheumatoid vasculitis, and 80 healthy controls. IgG and IgA antibodies to C1q, as measured by enzyme-linked immunosorbent assay, were found in less than 5% of the sera from RA patients and from healthy controls. In contrast, IgG and IgA antibodies to C1q were found in 29% and 61%, respectively, of the sera from patients with rheumatoid vasculitis. The occurrence of IgA antibodies to C1q has not been previously demonstrated. These results also demonstrate that IgG antibodies to C1q do not occur exclusively in systemic lupus erythematosus patients: Sera of patients with rheumatoid vasculitis frequently contain IgG or IgA antibodies to C1q, which contribute to immune complex formation.

Adult↗