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M R Daha

Publications and source records attributed to M R Daha.

At least 55 records · Page 3Linked to original sources
PubMed1999

Transforming growth factor-beta isoforms regulate the surface expression of membrane cofactor protein (CD46) and CD59 on human keratinocytes [corrected].

We studied the regulation of the expression of complement regulatory proteins, membrane cofactor protein (MCP), decay accelerating factor (DAF) and CD59, on human keratinocytes by supernatant of activated mononuclear cells and by some individual cytokines present therein. Cultured keratinocytes expressed MCP, DAF and CD59. Supernatant of activated mononuclear cells and recombinant forms of transforming growth factor (TGF)-beta variants (beta1, beta2 and beta3) up-regulated MCP and CD59 but not DAF. Recombinant IL-1alpha, IL-2, IL-6, TNF-alpha and IFN-gamma had no influence. TGF-beta present in the supernatant was likely responsible for up-regulation of MCP and CD59. A monoclonal anti-TGF-beta antibody, which neutralized TGF-beta1, -beta2 and -beta3, did not inhibit the up-regulation of MCP and CD59 by the supernatant. These results indicated that TGF-beta and an additional factor(s) present in the supernatant may be responsible for up-regulating the expression of MCP and CD59 on keratinocytes; both may be acting non-synergistically.

Antigens, CD↗
PubMed1999

Miller Fisher anti-GQ1b antibodies: alpha-latrotoxin-like effects on motor end plates.

In the Miller Fisher syndrome (MFS) variant of the Guillain-Barré syndrome, weakness is restricted to extraocular muscles and occasionally other craniobulbar muscles. Most MFS patients have serum antibodies against ganglioside type GQ1b of which the pathophysiological relevance is unclear. We examined the in vitro effects of MFS sera, MFS IgG, and a human monoclonal anti-GQ1b IgM antibody on mouse neuromuscular junctions (NMJs). It was found that anti-GQ1b antibodies bind at NMJs where they induce massive quantal release of acetylcholine from nerve terminals and eventually block neuromuscular transmission. This effect closely resembled the effect of the paralytic neurotoxin alpha-latrotoxin at the mouse NMJs, implying possible involvement of alpha-latrotoxin receptors or associated downstream pathways. By using complement-deficient sera, the effect of anti-GQ1b antibodies on NMJs was shown to be entirely dependent on activation of complement components. However, neither classical pathway activation nor the formation of membrane attack complex was required, indicating the effects could be due to involvement of the alternative pathway and intermediate complement cascade products. Our findings strongly suggest that anti-GQ1b antibodies in conjunction with activated complement components are the principal pathophysiological mediators of motor symptoms in MFS and that the NMJ is an important site of their action.

Animals↗
PubMed1999

C1q autoantibodies in HIV infection: correlation to elevated levels of autoantibodies against 60-kDa heat-shock proteins.

Antibodies to solid phase C1q (C1qAb) were determined in 295 serum samples from 132 HIV-infected subjects and in sera from 140 HIV-seronegative healthy individuals as control. An ELISA method applied for the determination of C1qAb in other diseases was used. In part of these sera, other autoantibodies (antibodies reacting with 60-kDa human heat shock protein (hsp60) or mycobacterial hsp65; IgA and IgG class antibodies against the Fab and F(ab')2 moieties of IgG) as well as complement-mediated antibody-dependent enhancement/neutralization (C'-ADE) were also determined. Increased amount of C1qAb was found in HIV-infected subjects as compared with HIV-seronegative controls (P = 0.0138). In 17 of 132 (13.0%) seropositive individuals but only in 7/140 (5.0%) samples from the controls, the amount of C1qAb exceeded the upper limit (95th percentile) of the normal values (P = 0.031). The amount of C1qAb significantly decreased during a follow-up period of 65 months. C1qAb levels were found to strongly correlate to hsp60/65 autoantibodies but did not correlate or only weakly correlated to the amount of anti-Fab or anti-F(ab')2 autoantibodies measured in the same serum samples. Anti-C1q antibodies recognized the solid phase hsp60/65. Three predicted epitope regions of M. paratuberculosis hsp65 were able to bind efficiently C1q antibodies. An inverse correlation was found between C1qAb and C'-ADE, neutralization was more frequent in the sera with detectable C1qAb, whereas sera without C1qAb more likely enhanced HIV infection in vitro.

Antigens, Bacterial↗
PubMed1999

Sequential development of anti-GBM nephritis and ANCA-associated Pauci-immune glomerulonephritis.

The medical history is presented of a 23-year-old man experiencing three episodes of pulmonary-renal syndrome. On the first occasion, a diagnosis of anti-glomerular basement membrane (GBM) disease (with linear deposition of immunoglobulin G [IgG] along the GBM) was made, whereas anti-neutrophil cytoplasmic autoantibodies were also present in serum. On the third occasion, 5 years later, p-ANCA-associated vasculitis (with pauci-immune crescentic glomerulonephritis) was diagnosed, whereas anti-GBM antibodies were absent. The current literature on ANCA-positive anti-GBM disease is briefly reviewed. A substantial proportion (20% to 30%) of patients with histologically and serologically proven anti-GBM nephritis display the presence of ANCA as well. In this group of patients with dual antibodies, clinical and histological findings suggest that ANCA are not merely epiphenomena, but are of pathogenetic importance and might be responsible for an initial vasculitic insult to the kidney with resultant secondary anti-GBM nephritis. The clinical course in our patient lends further support to this concept. Histological demonstration of anti-GBM nephritis followed by ANCA-associated pauci-immune glomerulonephritis in a single patient has not been reported before.

Adult↗
PubMed1999

Hyperacute rejection in the guinea pig-to-rat model without formation of the membrane attack complex.

The guinea pig (GP)-to-rat transplantation model has been widely used to study hyperacute rejection (HAR) of xenografts. In this model heart graft survival beyond 8 days has never been reported. In contrast, survival times of kidney and heart grafts up to 62 days have been reported in the discordant pig-to-primate model. It is not clear why it is so much more difficult to obtain long-term graft survival in the GP-to-rat model as compared to the pig-to-primate model. We hypothesized that mechanisms other than activation of complement may be involved in the rejection of guinea pig grafts by rat recipients. Therefore, we have studied in detail the rejection of GP aortic grafts by rat recipients, either PVG/c+ (complement competent, group 1), or PVG/c- (complement C6 deficient, group 2). PVG/c- rats are not able to form the membrane attack complex (MAC) of complement. Forty-four GP-to-rat aortic transplantations were performed successfully. Recipient rats were sacrificed at various intervals after transplantation (4, 24 and 48 h, and 7 and 28 days, three to six animals per time point per group). Twenty-four hours after transplantation the number of cells in the media was significantly decreased from 11.1 +/- 0.9 cells/mm2 to 3.1 +/- 2.8 cells/mm2 in group 1, whereas the number of medial cells in group 2 remained the same. The number of medial cells was significantly decreased in both groups at 48 h post-transplantation (group 1: 1.8 +/- 2.2 cells/mm2; group 2: 5.5 +/- 3.0 cells/mm2). At that time no infiltrating cells were apparent in the grafts of either two groups. Seven days after transplantation, the number of medial cells remained low in group 1 (1.8 +/- 2.9 cells/mm2) but was increased in group 2 (10.7 +/- 2.6 cells/mm2) as a consequence of infiltrating immune cells. These infiltrating cells consisted mainly of macrophages, but also T cells and NK cells. At 28 days after transplantation the grafts in both groups were completely reorganized and no distinction could be made between media and adventitia. These results show that rejection of GP grafts by rat recipients can occur in the absence of both MAC of complement and immune competent cells. This MAC and immune cells independent type of rejection has not been described before and may explain the difficulty in obtaining long-term graft survival in the GP-to-rat xenotransplantation model.

Acute Disease↗
PubMed1999

Combined administration of IgA and IgG anti-Thy-1 antibodies enhances renal inflammation in rats.

BACKGROUND: IgA nephropathy (IgAN) is the most common type of immunologically mediated glomerulonephritis (GN) and is characterized by deposition in the glomerular mesangium of IgA together with C3, C5b-9, and properdin. In patients, the codeposition of IgA together with IgG and/or IgM can lead to a more progressive course of disease. In Wistar rats, mesangial proliferative GN can be induced by the injection of mouse IgG anti-Thy-1 antibodies (ER4G). In contrast, the administration of mouse IgA anti-Thy-1 antibodies (ER4A) to rats results in isolated hematuria without detectable albuminuria and without detectable complement deposition. METHODS: To investigate the effect of the combination of IgA and IgG on glomerular injury, Wistar rats were injected with a limiting dose of ER4G in the presence or absence of ER4A in a dose able to induce hematuria. RESULTS: Although the limiting dose of ER4G or the dose of ER4A used did not induce significant albuminuria, the combination of ER4G and ER4A resulted in a synergistic increase in albuminuria. Microhematuria occurred in rats receiving either ER4A or ER4G alone or in combination. Although both ER4A or a limiting dose of ER4G induced minor increases in extracellular matrix expansion, the combination resulted in a pronounced, additive increased matrix expansion. CONCLUSION: We conclude that in this model of IgA-mediated glomerulopathy, a selective complement-dependent synergistic renal injury is induced in Wistar rats by glomerular codeposition of mouse anti-Thy-1 monoclonal isotypes.

Animals↗
PubMed1999

Synergistic effect of interleukin-1 and CD40L on the activation of human renal tubular epithelial cells.

BACKGROUND: Renal tubular epithelial cells are a central cell type in tubulointerstitial inflammation because they can produce inflammatory mediators such as cytokines and chemokines. Several signals derived from either monocytes or activated T cells have been reported to regulate the activation of tubular epithelial cells. We studied this regulation in more detail by combined treatment with CD40 ligand and the proinflammatory cytokine interleukin-1 (IL-1) in vitro. METHODS: The regulation of cytokine and chemokine production was studied in primary cultures of human proximal tubular epithelial cells (PTECs). PTECs were activated by coculture with CD40L-transfected murine fibroblasts in combination with recombinant human cytokines. The production of IL-6, IL-8, monocyte chemoattractant protein-1 (MCP-1), and RANTES were measured by specific enzyme-linked immunosorbent assay. RESULTS: The combined activation of PTECs with CD40L and IL-1 resulted in strong synergistic effects on the production of IL-6, IL-8, and RANTES, whereas only an additive stimulation of MCP-1 production was observed. The effects were specific for IL-1 and could be neutralized by the addition of the IL-1R antagonist. Both IL-1alpha and IL-1beta showed similar effects on cytokine production by PTECs. The effects of IL-1 were dose dependent, and kinetic experiments showed that synergistic effects were observed after 24 hours of activation and remained present for at least five days. Reverse transcription-polymerase chain reaction analysis showed that human PTECs could express both IL-1alpha and IL-1beta. The activation of PTECs with IL-1 resulted in an up-regulation of CD40 expression on these cells. CONCLUSIONS: A complex network of regulation exists for the production of cytokines and chemokines by PTECs. The combined treatment results in strong synergistic effects on IL-6, IL-8, and RANTES production. This strengthens the potential role of tubular epithelial cells in inflammatory responses within the kidney.

Animals↗
PubMed1999

Assessment of complement deficiency in patients with meningococcal disease in The Netherlands.

The frequency of complement deficiency in 176 of 7,732 patients with meningococcal disease in the Netherlands from 1959 through 1992 was assessed. Complement deficiency was found in six patients (3%): 3 (7%) of the patients with Neisseria meningitidis serogroup C disease, 1 (2%) of the patients with N. meningitidis serogroup A disease, and 2 (33%) of the patients with infections due to uncommon serogroups and nongroupable strains of N. meningitidis. Of 91 additional patients with meningococcal infections due to uncommon serogroups, 33% also had complement deficiency. Thirty-four of the 36 complement-deficient patients with meningococcal disease who were from 33 families were 5 years of age or older. Twenty-six additional complement-deficient relatives were found. Screening individuals with meningococcal disease due to uncommon serogroups who were 5 years of age or older identified 30 of the 33 complement-deficient families. Only 27% of the complement-deficient relatives had had meningococcal disease. This risk was lower for relatives with properdin deficiency (18%) than for those deficient in the late component of complement (38%). Therefore, pedigree studies are warranted for identifying those complement-deficient persons who require vaccination for meningococcal disease.

Adolescent↗
PubMed1999

Decreased IgA1 response after primary oral immunization with live typhoid vaccine in primary IgA nephropathy.

INTRODUCTION: Patients with primary IgA nephropathy (IgAN) have an increased level of immunological memory to certain parenteral recall antigens. We recently found a deficient IgA1 immune response after intranasal challenge with a neo-antigen: cholera toxin subunit B. In the present study, we assessed the specific IgA1 and IgA2 antibody response in plasma, peripheral blood cells and mucosal secretions after primary enteral immunization. METHODS: Twenty eight IgAN patients, 26 patients with non-immunological renal disease and 32 healthy subjects were immunized orally with three sequential doses of live, attenuated, Salmonella typhi Ty21a. The humoral immune response in body fluids and antibody synthesis by circulating B cells was assessed in specific ELISAs and ELIPSAs respectively. RESULTS: Oral immunization resulted in significantly (P<0.0001) increased IgM, IgG, IgA, IgA1 and IgA2 responses in all groups, both in plasma and in circulating B cells in vitro. The IgA1 response in plasma was significantly (P<0.05) lower in IgAN patients, while no significant differences in IgM (P=0.36), IgG (P= 0.79) or IgA2 (P=0.45) responses were found as compared with matched control groups. The amount of IgA1 synthesized by circulating B cells tended to be lower in IgAN patients. No significant IgA response after oral immunization with S. typhi Ty21a was found in saliva (P=0.11) or tears (P=0.10). CONCLUSIONS: These data suggest an IgA1 hyporesponsiveness in patients with IgAN that is not only apparent after primary challenge of the nasal-associated lymphoid tissue but also after presentation to the gut. Previous results after parenteral recall immunization may be explained by assuming that IgAN patients require more frequent and/or longer exposure to IgA1-inducing antigens on their mucosal surfaces before they reach protective mucosal immunity. As a consequence, overproduction of IgA1 antibodies occurs in the systemic compartment, accompanied by an increased number of IgA1 memory cells.

Administration, Oral↗
PubMed1999

Resistance to both complement activation and phagocytosis in type 3 pneumococci is mediated by the binding of complement regulatory protein factor H.

To study the role of surface-associated proteins in the virulence of Streptococcus pneumoniae, we used two serotype 3 strains, ATCC 6303 and WU2, and two PspA-negative mutants of WU2, an encapsulated one, JY1123 (Caps(+)/PspA(-)), and an unencapsulated one, DW3.8 (Caps(-)/PspA(-)). ATCC 6303 and WU2 were highly virulent in mice, while the virulence of JY1123 was slightly decreased (50% lethal doses [LD(50)s], 24, 6, and 147 CFU/mouse, respectively); DW3.8 was avirulent (LD(50), 2 x 10(8) CFU). In vitro, ATCC 6303, WU2, and JY1123 (Caps(+)/PspA(-)) strongly resisted complement activation and complement-dependent opsonophagocytosis, whereas DW3.8 (Caps(-)/PspA(-)) was easily phagocytized in fresh serum. Trypsin treatment of ATCC 6303, WU2, and JY1123 (Caps(+)/PspA(-)) resulted in enhanced complement activation and complement-dependent opsonophagocytosis. Trypsin had no deleterious effect on the polysaccharide capsule. In addition, trypsin pretreatment of ATCC 6303 strongly reduced virulence upon intraperitoneal challenge in mice. This indicated that surface proteins play a role in the resistance to complement activation and opsonophagocytosis and contribute to the virulence of type 3 pneumococci. In subsequent experiments, we could show that the modulation of complement activation was associated with surface components that bind complement regulator factor H; binding is trypsin sensitive and independent of prior complement activation. Immunoblotting of cell wall proteins of the virulent strain ATCC 6303 with anti-human factor H antibody revealed three factor H-binding proteins of 88, 150, and 196 kDa. Immunogold electron microscopy showed a close association of factor H-binding components with the outer surface of the cell wall. The role of these factor H-binding surface proteins in the virulence of pneumococci is interesting and warrants further investigation.

Animals↗
PubMed1999

Role of tubular cells in progressive renal disease.

It is generally accepted that the progressive loss of kidney function results from a pathogenic process that is independent of the original etiology, functioning as a final common pathway. Part of this response is characterized by triggering of interstitial infiltration and induction of tubular damage. As a consequence, tubular epithelial cells (TEC) can become activated and begin to express several inflammatory mediators. In the present review, we will summarize the potential role of TEC in progressive renal disease. Much emphasis will be put on studies using in vitro cultured TEC. These studies have provided more insight into the different signals involved in the regulation of the production of inflammatory mediators like complement, cytokines and chemokines, as well as progression factors like growth factors and matrix component by TEC.

Animals↗
PubMed1999

Human mesangial cells in culture and in kidney sections fail to express Fc alpha receptor (CD89).

The mechanism of deposition of IgA in the renal mesangium in primary IgA-nephropathy is poorly understood. It has been suggested that membrane receptors for IgA on mesangial cells (MC) of the kidney may be involved. To obtain more insight in the occurrence of the myeloid receptor for IgA (CD89) on MC, both in situ and in culture, rabbit and goat polyclonal antibodies and mouse monoclonal antibody against recombinant CD89 were raised. Kidney sections from five control subjects and five patients with primary IgA-nephropathy failed to be positive for CD89 in the mesangium, using our polyclonal and monoclonal antibodies. Also, five primary human MC cultures assessed for CD89 expression showed no protein expression of CD89. Furthermore, reverse transcription-PCR failed to detect mRNA expression of CD89 in the cultured MC. It was demonstrated that all five human primary MC bound human IgA in a dose-dependent manner, which was not inhibitable by blocking monoclonal anti-CD89 antibody (My43). In contrast, binding of IgA to U937 cells was blocked efficiently by My43. Finally, incubation of human MC with either human or rat IgA led to increased interleukin-6 production, whereas only human IgA, but not rat IgA, was able to bind to human CD89. Therefore, it is concluded that human MC do not express CD89 (to a significant extent). These results strongly suggest that binding of IgA to human MC occurs via an IgA receptor distinct from CD89.

Animals↗
PubMed1999

The terminal sequence of complement plays an essential role in antibody-mediated renal cell apoptosis.

Mesangial cell (MC) injury is a characteristic feature in the early phase of Thy.1 nephritis. The present study investigates the contribution of complement to MC apoptosis in this experimental model of kidney disease in rats. Thy.1 nephritis was induced by injection of mouse anti-Thy.1 monoclonal antibody (ER4G). To assess the contribution of the terminal sequence of complement on apoptosis, the studies were performed in complement-sufficient PVG/c (PVG/c+) rats and in rats deficient in complement C6 (PVG/c-). Apoptosis was monitored by assessment of the number of condensed nuclei in kidney sections stained with periodic acid-Schiff (PAS) and by the terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) method and expressed as number of apoptotic cells per 50 glomerular cross sections. In the PAS method, 1 h after intravenous injection of ER4G, PVG/c+ rats exhibited 160.9 +/- 49.5 apoptotic cells, whereas PVG/c- rats had only 3.2 +/- 1.4 apoptotic cells. Control rats exhibited 0.9 +/- 0.6 apoptotic cells. These findings were confirmed with the TUNEL method. In PVG/c- rats, a maximum number of 8.8 +/- 3.1 TUNEL-positive (TUNEL+) cells was found at 6 h followed by a decline thereafter. In PVG/c+ rats, apoptosis was associated with deposition of C6 and C5b-9. Restoration of the complement system of PVG/c- rats with purified human C6 resulted in an increase of apoptosis at 1 h after injection of ER4G from minimal numbers to 239.9 +/- 52.4 TUNEL+ cells. These studies appear to indicate for the first time that the terminal sequence of complement is involved in induction of apoptosis.

Analysis of Variance↗
PubMed1999

The DD genotype of the ACE gene polymorphism is associated with progression of diabetic nephropathy to end stage renal failure in IDDM.

BACKGROUND: The insertion-deletion (I/D) polymorphism of the angiotensin converting enzyme gene is a diallelic polymorphism that constitutes a genetic influence on the progression of renal diseases such as IgA nephropathy. Patients with the DD genotype have an accelerated progression towards end stage renal failure in these diseases. The role of the I/D polymorphism in the pathogenesis of diabetic nephropathy in IDDM is unresolved. PATIENTS AND METHODS: We therefore set out to study the contribution of the I/D polymorphism in 79 patients (age 39.5 +/- 7.6 years (mean +/- SD) with end stage renal failure due to diabetic nephropathy, who were recipients of a combined kidney-pancreas transplantation (n = 60), or who were on the waiting list for such a procedure (n = 19). The control series consisted of 82 patients (age 39.5 +/- 9.6 years) without microalbuminuria after fifteen years of IDDM. RESULTS: The ACE genotype distribution in patients was not in accordance with the Hardy-Weinberg equilibrium due to a significant overrepresentation of the DD genotype (X2 = 8.9, p = 0.01). This resulted in a significant increase of the D-allele frequency in the cases compared to controls (X2 = 4.9, p = 0.03). The presence of one D-allele did not increase the risk of end stage renal failure (odds ratio ID/II = 1.0, 95% CI 0.4-2.2). The presence of the DD genotype increased the risk of end stage renal failure twofold compared to the other genotypes (odds ratio 2.1, 95% CI 1.1-4.0). The risk estimate seemed slightly higher in patients with good metabolic control (odds ratio 2.6, 95% CI 1.0-7.1), than in patients with poor control (odds ratio 1.6, 95% CI 0.59-4.3). CONCLUSION: It is concluded that the risk of end-stage renal failure in patients with IDDM is twofold increased in patients with the DD genotype as compared to patients with other genotypes.

Adult↗
PubMed1998

The first subcomponent of complement, C1q, triggers the production of IL-8, IL-6, and monocyte chemoattractant peptide-1 by human umbilical vein endothelial cells.

We and others have demonstrated previously the occurrence of cC1qR/CaR, a receptor for the collagen-like stalks of complement component C1q, on endothelial cells. In the present study we investigated whether binding of C1q to endothelial cells resulted in enhancement of cytokine or chemokine production. HUVEC produced 82 +/- 91 pg/ml of IL-8, 79 +/- 113 pg/ml of IL-6, and 503 +/- 221 pg/ml of monocyte chemoattractant peptide-1 (MCP-1) under basal conditions. Incubation with C1q resulted in a time- and dose-dependent up-regulation of IL-8 (1012 +/- 43 pg/ml), IL-6 (392 +/- 20 pg/ml), and MCP-1 (2450 +/- 101 pg/ml). This production is dependent on de novo protein synthesis, as demonstrated by the detection of specific mRNA after C1q stimulation, and inhibition of peptide production in the presence of cycloheximide. The production of all factors was inhibited (69 +/- 7%) by the collagenous fragments of C1q, while the C1q globular heads only induced 13 +/- 11% inhibition. When HUVEC were incubated with C1q in the presence of aggregated IgM, enhanced production of IL-8 (2500 +/- 422 pg/ml), IL-6 (997 +/- 21 pg/ml), and MCP-1 (5343 +/- 302 pg/ml) was found. Furthermore, F(ab')2 anti-calreticulin partially inhibited the production of IL-8, confirming at least the involvement of cC1qR/CaR. These experiments suggest that in an inflammatory response C1q not only is able to activate the complement pathway, but when presented in a proper fashion also might induce the production of factors that contribute to acute phase responses and recruitment of inflammatory cells.

Animals↗
PubMed1998

Inhibition of activation of the classical pathway of complement by human neutrophil defensins.

Defensins are small, cationic antimicrobial peptides that are present in the azurophilic granules of neutrophils. Earlier studies have shown that defensins may influence complement activation by specific interaction with activated C1, C1q, and C1-inhibitor. In the present study, we show that the defensin human neutrophil peptide-1 (HNP-1) is able to inhibit activation of the classical complement pathway by inhibition of C1q hemolytic activity. The binding site for HNP-1 on C1q is most likely located on the collagen-like stalks, as a clear, dose-dependent binding of HNP-1 to either intact C1q or to the collagen-like stalks of C1q was demonstrated using enzyme-linked immunosorbent assay (ELISA). Besides binding of HNP-1 to C1q, also a limited binding to C1 and to a mixture of C1r and C1s was observed, whereas no binding to C1-inhibitor was found. Because binding of HNP-1 to C1-inhibitor has been suggested in earlier studies, we also assessed the binding of HNP-1 to mixtures of C1-inhibitor with either C1r/ C1s or C1. No binding was found. Using a competition ELISA, it was found that HNP-1, but not protamine, inhibited binding of biotin-labeled HNP-1 to C1q in a dose-dependent fashion. In the fluid phase, preincubation of HNP-1 with C1q resulted in complex formation of HNP-1 and C1q and generation of stable complexes. In conclusion, HNP-1 is able to bind to C1q in the fluid phase and inhibits the classical complement pathway. This mechanism may be involved in the control of an inflammatory response in vivo.

Binding Sites↗
PubMed1998

Mechanisms of lymphocyte-mediated cytotoxicity in acute renal allograft rejection.

BACKGROUND: Graft-infiltrating T-cell (GIC) lines cultured from biopsies obtained during acute renal allograft rejection exhibit donor-specific cytotoxicity toward proximal tubular epithelial cell (PTEC) lines cultured from corresponding biopsies. This system allows for study of the relative contributions of perforin/granzyme B (GrB)- and Fas ligand (FasL)-based cytotoxicity to killing of PTEC. METHODS: Expression of perforin, GrB and FasL was analyzed by immunocytochemical staining of cytocentrifuge preparations of GIC lines cultured from 10 renal allograft biopsies. Specific inhibitors of the perforin/GrB- and FasL-based pathways were used in 51Cr release and apoptosis assays to determine their relative contributions to cytotoxicity of GIC lines toward corresponding donor PTEC lines. RESULTS: Cells with a strong granular pattern were observed upon immunocytochemical staining of GIC lines with anti-perforin or anti-GrB monoclonal antibodies. A diffuse staining pattern was observed upon staining with anti-FasL polyclonal antibodies. Six of eight GIC lines cultured from biopsies with acute rejection showed cytotoxicity toward corresponding donor PTEC lines, whereas two GIC lines cultured from biopsies without rejection did not. Preincubation of cytotoxic GIC lines with concanamycin A, an inhibitor of the perforin/GrB-based pathway, caused inhibition of both lysis and apoptosis of PTEC. Inhibition was not observed upon incubation with monoclonal antibodies that inhibit Fas. CONCLUSIONS: The perforin/GrB-based pathway is mainly responsible for cytotoxicity of GIC lines toward corresponding donor PTEC lines, suggesting that this pathway predominates in tubular epithelial cell destruction by cytotoxic T lymphocytes during acute renal allograft rejection in vivo.

Acute Disease↗