Upregulation of adhesion molecule expression on endothelial cells by anti-DNA autoantibodies in systemic lupus erythematosus

The mechanism of vasculopathy in systemic lupus erythematosus (SLE) remains unclear and the evidence for a direct pathogenic role of anti-double-stranded DNA antibodies (anti-dsDNA) is not strong. Our study aims to determine whether anti-dsDNA exerts any effect on the expression of adhesion molecules on endothelial cells. IgG was purified from 17 patients with SLE (median anti-dsDNA titer, 404 IU/ml) and from 9 healthy controls (median titer 16 IU/ml). Anti-dsDNA-depleted polyclonal IgG (anti-dsDNA-dep-IgG) (median anti-dsDNA titer 17 IU/ml) was prepared from sera of these patients with SLE by affinity chromatography with DNA cellulose column. Expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin on human umbilical vein endothelial cells (HUVEC) cultured with either control IgG or anti-dsDNA were compared by flow cytometry. The levels of adhesion molecules in the supernatant of cultured HUVEC were assessed by sandwich ELISA. Compared with either control IgG or anti-dsDNA-dep-IgG, HUVEC incubated with anti-dsDNA expressed a significantly higher mean fluorescence intensity of ICAM-1 and in VCAM-1 and a higher supernatant concentration of ICAM-1 and VCAM-1 but not E-selectin. At the same time, ICAM-1 mRNA was also raised with increased neutrophil adherence in HUVEC incubated with anti-dsDNA. Pretreatment of HUVEC with native DNA or histone before incubation with anti-dsDNA did not increase the expression of adhesion molecules. Our study provides in vitro evidence that anti-dsDNA could play an important pathogenic role in inducing inflammatory injury of vascular endothelium in SLE.

Interleukin-5 messenger RNA expression in peripheral blood CD4+ cells in asthma

BACKGROUND

IL-5 has been implicated in the pathogenesis of asthma through its regulatory role on eosinophil survival, proliferation, and effector function.

OBJECTIVE

The study was designed to investigate the relationships between IL-5 messenger RNA expression in circulating CD4+ cells and serum concentrations of eosinophil cationic protein (ECP), a marker of eosinophil activation, and disease activity in asthma.

METHODS

IL-5 gene expression was assessed semiquantitatively in ex vivo stimulated CD4+ cells by reverse transcription-polymerase chain reaction and serum ECP concentration measured from venous blood samples collected from patients with acute severe asthma before the commencement of systemic steroid therapy (day 1) and on day 7 and from patients with stable asthma and healthy volunteers.

RESULTS

IL-5 gene expression was significantly higher in patients with acute asthma before steroid treatment than in those with stable disease and healthy subjects (p < 0.0001). Similar results were obtained with serum ECP levels: levels in patients with acute asthma were highest (20.30 +/- 5.31 micrograms/L), followed by levels in patients with stable asthma (2.76 +/- 0.65 micrograms/L) and levels in normal control subjects (1.37 +/- 0.06 micrograms/L; p < 0.01 for all comparisons). Significant falls in both IL-5 expression and serum ECP level were seen on day 7 (p < 0.001) and coincided with a significant improvement in peak expiratory flow (p < 0.0001). Significant correlations were observed between IL-5 expression and ECP level (rho = 0.39, p < 0.01), IL-5 expression and peak expiratory flow (rho = -0.55, p < 0.0002), and peak expiratory flow and ECP level (rho = -0.32, p < 0.04).

CONCLUSION

Our data therefore support an important regulatory role of IL-5 on eosinophil function in human asthma in vivo.

Serologic study of immunoglobulin A-fibronectin aggregates in immunoglobulin A nephropathy

The immunoglobulin A (IgA)-fibronectin aggregates, detected by enzyme-linked immunosorbent assay using either antifibronectin or collagen I as binding protein, were previously found to be raised in the circulation of patients with IgA nephropathy (IgAN). It has been suggested that IgA-fibronectin aggregates are involved in the pathogenesis and that the plasma IgA-fibronectin level may even be of diagnostic value in IgAN. Nevertheless, a recent report has questioned the specificity of these assays as plasma IgA may interact with immobilized IgG and these assays detect not only IgA-fibronectin, but also total plasma IgA. These doubts render the interpretation of raised IgA-fibronectin aggregates in IgAN impossible. We isolated total IgA, in plasma by jacalin-agarose. Monomeric and polymeric IgA1 were distinctly separated by fast protein liquid chromatography. When the fast protein liquid chromatography fractions were analyzed for IgA-fibronectin using the antifibronectin capture assay, increased optical density values were predominantly observed in polymeric IgA but not in monomeric IgA. Similar findings were found when the fast protein liquid chromatography fractions were studied using a novel gelatin-anti-IgA assay that avoided nonspecific interaction between plasma IgA and immobilized IgG used as the capture antibody in antifibronectin capture assay. Using our gelatin-anti-IgA assay, we failed to demonstrate a diagnostic increase in IgA-fibronectin aggregates in polymeric IgA from patients with IgAN compared with controls. Our finding of circulating IgA-fibronectin aggregates in patients with IgAN comparable to those of healthy controls did not support the notion that these aggregates may have a pathogenetic role or diagnostic value in IgAN.

Anti-DNA autoantibodies stimulate the release of interleukin-1 and interleukin-6 from endothelial cells

The pathogenetic mechanism of vasculitis in systemic lupus erythematosus (SLE) remains a subject of debate. Evidence for a direct pathogenetic role of anti-double-stranded DNA antibodies (anti-dsDNA) is not strong. Supernatant concentrations of interleukin-1 beta and interleukin-6, and mRNAs encoding for interleukin-1 alpha and interleukin-1 receptor-1 were determined in cultured human umbilical vein endothelial cells (HUVEC), incubated with control IgG (n = 18), anti-dsDNA (n = 18), or IgG from the same lupus patient depleted of anti-dsDNA by affinity chromatography (anti-dsDNA-dep-IgG). Compared with control IgG, there was a significant increase of supernatant interleukin-1 beta and interleukin-1 alpha mRNA in endothelial cells incubated with anti-dsDNA. The supernatant interleukin-1 beta and interleukin-6, and mRNAs encoding for interleukin-1 alpha and interleukin-1 receptor-1, were significantly elevated in endothelial cells incubated with anti-dsDNA, compared with those incubated with anti-dsDNA-dep-IgG. Pretreating HUVEC with native DNA before incubating with anti-dsDNA did not result in an additive effect. These in vitro studies suggest that anti-dsDNA plays an important pathogenetic role in inducing inflammatory injury of vascular endothelium in SLE.

Increased binding of polymeric lambda-IgA to cultured human mesangial cells in IgA nephropathy

IgA nephropathy (IgAN) is characterized by raised plasma lambda-IgA1 and mesangial polymeric lambda-IgA1 deposits. It remains uncertain whether the predominant glomerular lambda-IgA1 deposits represent a selective uptake of polymeric IgA or a non-specific uptake due to elevated circulating lambda-IgA1 levels in response to an unidentified antigen. In this study, we explored whether there is an increased binding of monomeric IgA1 (mIgA1) or polymeric IgA1 (pIgA1) from patients with IgAN to cultured human mesangial cells (HMC). Total IgA1 in plasma from patients or healthy controls was isolated by jacalin-agarose column as jacalin-bound proteins (JBP). Monomeric IgA1 and pIgA1 were distinctly separated by FPLC. HMC were incubated with IgA preparations and IgA bound to HMC was determined by flow cytometry analysis using standard curves constructed by known concentrations of kappa-IgA1 or lambda-IgA1. In order to avoid any increased binding of IgA to HMC due to elevated kappa- or lambda-IgA concentrations in JBP samples from patients, JBP samples from patients or controls were appropriately diluted to achieve comparable levels of total IgA1. No differences in the total mIgA1 or pIgA1 concentration, percentage of mIgA1 or pIgA1, or the kappa/lambda ratio of mIgA1 or pIgA1 were found between adjusted JBP samples from patients or healthy controls. We found a sharp rise in percentage of pIgA1 among IgA1 bound to HMC (70%), despite the fact that only 3% of the IgA1 in the adjusted JBP samples were polymeric, suggesting that pIgA1 had a higher affinity to HMC than mIgA1. Furthermore, the kappa/lambda ratios of pIgA1 bound to HMC were significantly lower than the kappa/lambda ratios of pIgA1 in adjusted JBP only with IgAN patients but not healthy controls (P = 0.0026). Our data suggest a preferential mesangial binding of polymeric lambda-IgA1 from patients with IgAN. These polymeric lambda-IgA immune complexes are likely to be "pathogenic" and are important in the pathogenesis of IgAN.

Increased release of von Willebrand factor antigen from endothelial cells by anti-DNA autoantibodies

OBJECTIVE

To determine whether antibodies to double stranded DNA (anti-dsDNA) have a pathogenic role in systemic lupus erythematosus (SLE).

METHODS

IgG was purified from 17 patients with SLE (median anti-dsDNA titre 1212 IU/ml) and nine healthy controls (median titre 40 IU/ml). Anti-dsDNA depleted polyclonal IgG (median anti-dsDNA titre 17 IU/ml) was also prepared from sera of the 17 patients by affinity chromatography on a DNA cellulose column. Binding to antiendothelial cell antibodies (AECA) and expression of von Willebrand factor (VWF) antigen by cultured human umbilical vein endothelial cells (HUVECs) were studied by flow cytometry.

RESULTS

The percentage of HUVECs binding to AECA or expressing VWF was greater for cells incubated with IgG from patients with SLE than for cells incubated with control IgG, though values did not reach statistical significance; nevertheless, HUVECs incubated with IgG from patients expressed a greater mean fluorescence intensity with AECA (p = 0.0001) and greater VWF expression (p = 0.019). Both the fluorescence intensity and percentage of HUVECs binding to AECA or expressing VWF were significantly greater in HUVEC incubated with IgG containing anti-dsDNA than in those incubated with anti-dsDNA depleted IgG. The concentration of VWF in the supernatant was significantly increased in HUVECs incubated with IgG containing anti-dsDNA compared with control IgG or anti-dsDNA depleted IgG. Pretreatment of HUVECs with native DNA before incubation with IgG from lupus patients did not increase binding to AECA, or expression or release of VWF.

CONCLUSIONS

Our study provides in vitro evidence that antibodies to DNA have a pathogenic role in the induction of inflammatory injury of the vascular endothelium in SLE.

The mechanism of ion conduction by valinomycin: analysis of charge pulse responses

Even though valinomycin has been employed and studied extensively for over 30 years, the attempts to explain its mechanism have not been entirely successful. The basic carrier model uses four rate constants that describe association of an ion and carrier, transfer of the complex across the membrane, dissociation of the complex, and transfer of the free carrier back across the membrane. If the basic model is correct all of these constants are independent of ion concentration. In previous work with rubidium the rate constants for transfer of free carrier, transfer of complexes, and dissociation were independent of the concentration, but the rate constant for association varied markedly. No satisfactory explanation for these observations was proposed. In this study current relaxations after charge pulses have been analyzed using digital data acquisition, a Bayesian algorithm, and inspection of linear plots of residuals. In agreement with previous results the relaxations for sufficiently high rubidium or potassium concentrations contain three exponential components, but the rate constants for association and dissociation decrease to similar extents as ion concentration increases. A simple extension of the carrier model to allow a more realistic description of association and dissociation is in good agreement with the rate constants fitted in the present study but not those for low ion concentrations found in previous work. At high ion concentrations the rate-limiting step in association appears to be a change in the conformation of the free carrier preceding the bimolecular association reaction. Transfer of neutral, free valinomycin between the surfaces is slower than the transfer of the charged ion-valinomycin complexes. Transfer of the complex may be hastened by deformation of the membrane, or transfer of the free carrier may be slowed by a need for conformation changes.

Biliary IgA secretion in obstructive jaundice: the effects of endoscopic drainage

BACKGROUND

Immunoglobulin A is the predominant immunoglobulin in the bile. Data on the effects of biliary obstruction on IgA secretion are few.

METHODS

The serum and bile IgA levels in patients with common duct stones (n = 27) or with malignant obstructive jaundice (n = 20) were collected by insertion of nasobiliary catheters. Single samples of common duct bile from patients with gallstones (n = 24) were collected as controls. Bile samples collected were measured for total IgA, secretory IgA, and free secretory component levels by sandwich enzyme-linked immunosorbent assays.

RESULTS

Bile total IgA, secretory IgA, and free secretory component in the common duct stones group (82.7 +/- 11.4 microgram/ml, 18.4 +/- 1.7 microgram/ml, 0.74 +/- 0.15 microgram/ml) and the malignant obstructive jaundice group (81.6 +/- 10.7 microgram/ml, 18.2 +/- 2.4 microgram/ml, 0.57 +2- 0.12 microgram/ml) were found to be significantly lower than those of the control gallstone patients (104.8 +/- 3.4 microgram/ml, 33.2 +/- 2.9 microgram/ml, 1.03 +/- 0.12 microgram/ml) (P < 0.05). Serum secretory IgA levels in the common duct stones (26.53 +/- 1.75 microgram/ml) and malignant obstructive jaundice groups (26.03 +/- 3.48 microgram/ml) were significantly higher than the gallstone group (18.45 +/- 4.56 microgram/ml). The bile-to-serum concentration ratio of total IgA, secretory IgA, and free secretory component levels rose significantly within 48 hours after relief of obstruction.

CONCLUSIONS

Biliary obstruction secondary to both calculus or malignancy of the hepatobiliary system causes suppression of bile IgA secretion and elevated serum level of secretory IgA. Bile secretory IgA secretion recovers with endoscopic drainage of the obstructed system.

Identification and characterization of human serum alpha2-HS glycoprotein as a jacalin-bound protein

We recently adopted immobilized jacalin as an affinity adsorbent to purify human serum IgA for laboratory study. In the course of our investigation, we detected a serum protein that co-eluted with IgA from jacalin-agarose affinity column. It constituted in significant quantity (24.0 +/- 0.9%, n = 30) of total jacalin-bound protein (JBP) and the yield was equivalent to 0.4 +/- 0.1 mg per ml serum. The molecular mass of this protein was 55 kDa with electromobility in the alpha 2 region as demonstrated by SDS-PAGE and immunoelectrophoresis. N-terminal microsequencing of this 55 kDa protein revealed that it is human alpha 2-HS glycoprotein (alpha 2HSG). The molecular interaction of alpha 2HSG with jacalin was characterized by competitive ELISA: human serum IgA, human colostrum secretory IgA (sIgA), and monosaccharides including D-galactose and melibiose exhibited strong inhibitory effect on its binding to jacalin. Accordingly, we propose that human alpha 2HSG binds in a similar manner as that of the bovine fetuin to jacalin. In addition, alpha 2HSG displays similar binding property to jacalin from different geographic area (India and Malaysia) and from different laboratory preparations (Sigma, Pierce and 'homemade' jacalin).

Elevated interleukin-2 receptor level in patients with active pulmonary tuberculosis and the changes following anti-tuberculosis chemotherapy

Soluble interleukin-2 receptor (sIL-2R) is a marker of T-lymphocyte activation. We have undertaken a study to examine the serum sIL-2R levels in patients with pulmonary tuberculosis (TB) and the changes following anti-TB chemotherapy. Forty four patients with pulmonary TB or tuberculous pleural effusion were recruited. Serum was collected from the patients before and at 1, 2, 4 and 6 months after initiation of anti-TB chemotherapy. Serum sIL-2R level was measured by an enzyme immunoassay. The mean sIL-2R level before treatment was 1,452 +/- 103 (SEM) U.ml-1, which was significantly higher than that of healthy control subjects (374 +/- 30 U.ml-1). There was no significant change in the sIL-2R level at 1 month, but there was a gradual reduction from the second month onwards. At the sixth month the mean sIL-2R level was 1080 +/- 81 U.ml-1, which was significantly lower than that before treatment. However, despite clinical improvement, the sIL-2R levels at the sixth month were still significantly higher than those of control subjects. We conclude that sIL-2R levels were elevated in patients with pulmonary TB and there was a gradual reduction following anti-TB chemotherapy. However, the sIL-2R levels were still higher than control subjects at completion of treatment, suggesting a delayed resolution of the inflammation in patients with pulmonary TB.

Heat-aggregated IgA prepared from patients with IgA nephropathy increases priming of human neutrophils to produce inositol triphosphate following FMet-Leu-Phe stimulation in vitro

It is envisaged that circulating IgA complexes play a primary role in the glomerular injury of IgA nephropathy, the most common glomerulonephritis worldwide. In this study, we examined the pathophysiological effects of IgA and IgG isolated from IgA-nephritic patients on the signal transduction of human neutrophils. Heat-aggregated forms and monomers of IgA and IgG were prepared from sera of 11 IgA-nephritic patients and 11 healthy controls. Signal transduction was studied by measuring the inositol triphosphate (IP3) production in neutrophils incubated with the immunoglobulin preparations. Different forms of IgA or IgG from IgA-nephritic patients failed to induce a significant increase in IP3 production directly as compared with control IgA or IgG. However, neutrophils preincubated with heat-aggregated IgA (HAA) from IgA-nephritic patients demonstrated a significant rise in IP3 production upon subsequent stimulation by a chemotactic peptide, FMet-Leu-Phe (FMLP); a similar finding was not observed with heat-aggregated IgG. HAA pretreatment of neutrophils increased FMLP-induced IP3 production in a dose-dependent manner. The raised IP3 production was not due to increased FMLP receptors, as HAA preincubation of neutrophils did not increase the binding of tritiated FMLP. The increased IP3 production upon FMLP stimulation in HAA-primed neutrophils was completely abolished by pertussis toxin in a dose-dependent manner. These findings tend to refute a direct stimulatory effect of HAA on phospholipase C, but, instead, may suggest that HAA prepared from IgA-nephritic patients upregulates the activation of G proteins in the plasma membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

CD4-positive cells from patients with IgA nephropathy demonstrate increased mRNA of cytokines that induce the IgA switch and differentiation

IgA nephropathy (IgAN) is characterized by raised serum IgA1 and mesangial IgA1 deposits. We have previously shown increased T-cell activation in IgAN. Recently, transforming growth factor-beta (TGF-beta) has been shown to induce IgA isotype switch at a clonal level and interleukin 5 (IL5) promotes differentiation into IgA-bearing B cells. In the present study we have examined the TGF-beta and IL5 mRNA expression by mitogen-activated CD4-positive T cells from patients with IgAN (n = 25), patients with other primary nephritides (CGN) (n = 24), and healthy control subjects (n = 25). The cytokine genes were analysed by reverse transcription (RT)-polymerase chain reaction (PCR) and were semi-quantitated by normalizing the differences occurring during RT and PCR using a housekeeping gene, beta-actin. CD4-positive T cells from IgA nephritic patients expressed a higher level of IL5 mRNA than healthy controls (P < 0.01) and patients with CGN (P < 0.005). CD4-positive T cells from IgA nephritic patients expressed a higher level of TGF-beta mRNA than healthy controls (P < 0.01) but no difference was demonstrated on comparison with CGN patients. Elevated TGF-beta mRNA expression in patients with CGN probably reflects its other important function as a 'sclerogenic' factor involved in the glomerulosclerosis found in these nephritides. Our data suggest that there is increased expression of cytokine genes which induce the IgA isotype switch and differentiation; these immunological abnormalities may be important in the pathogenesis of IgAN.

Increased mRNA encoding for transforming factor-beta in CD4+ cells from patients with IgA nephropathy

IgA nephropathy (IgAN) is a mesangial proliferative glomerulonephritis characterized by predominant mesangial IgA deposits. Recently, transforming growth factor-beta (TGF-beta) is shown to exert widespread effects on extracellular matrix by enhancing its accumulation. In an experimental model of acute mesangial glomerulonephritis TGF-beta appeared to be involved in the process of glomerulosclerosis, and treatment with antagonists of TGF-beta prevented the development of glomerulosclerosis. We examined the TGF-beta mRNA expression by mitogen activated CD4+ T cells from 31 patients with IgAN, 25 healthy controls and 10 patients with minimal change nephropathy (MCN) or focal glomerulonephritis (FGN) who were comparable in age and sex. The cytokine gene was analyzed with reverse transcription followed by polymerase chain reaction and was semiquantitated by normalizing the differences occurring during reverse transcription and polymerase chain reaction using a housekeeping gene, beta-actin. CD4+ T cells from IgA nephritic patients expressed a higher level of TGF-beta mRNA than that of healthy controls or that of MCN/FGN [TGF-beta/actin ratio 1.11 (median), range 0.24 to 3.87 vs. 0.88, range 0.2 to 3.83, P = 0.0157 and 0.36 range 0.09 to 1.6, P = 0.006]. When the biopsies were classified into three grades according to the severity of glomerular and interstitial pathology, there were highly significant differences between the TGF-beta mRNA in CD4+ T cells from the three groups of IgA nephritic patients (grade 1, 0.52, range 0.24 to 0.79; grade 2, 1.2, range 0.5 to 3.33; grade 3, 2.17, range 1.45 to 3.87].(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-neutrophil cytoplasmic antibodies (ANCA) and inflammatory bowel diseases in Chinese

Inflammatory bowel diseases are uncommon in the Chinese, but the incidence is rising. Their differentiation from infective colitis is often not clear-cut and diagnosing inflammatory bowel diseases can be difficult in Asia. We have studied Chinese patients with ulcerative colitis (N = 19) and Crohn's disease (N = 12) for anti-neutrophil cytoplasmic antibodies (ANCA) by indirect immunofluorescence (IIF) and enzyme-linked immunosorbent assays (ELISA). Patients with enteric fever (N = 29) and irritable bowel syndrome (N = 24) were recruited as controls. Seventy-three percent of ulcerative colitis patients exhibited either p-ANCA (31%) or c-ANCA (42%) by IIF. Twenty-five percent of Crohn's disease patients were found to be p-ANCA positive. However, these ANCA were nonreactive to anti-alpha granule, antiproteinase 3, antimyeloperoxidase, or antilactoferrin. All positive patients had extensive colitis. Sera collected from patients suffering from enteric fever and irritable bowel syndrome were negative for ANCA by IIF and ELISA. We concluded that the detection of ANCA is helpful in diagnosing inflammatory bowel diseases. Further attempts to characterize these autoantibodies are needed.

Effect of anti-neutrophil cytoplasm autoantibodies on the intracellular calcium concentration of human neutrophils

BACKGROUND

The discovery of circulating autoantibodies to neutrophil cytoplasm antigens (ANCA) has implicated autoimmune mechanisms in the pathogenesis of systemic vasculitis although it is uncertain whether these play a primary role or arise secondary to neutrophil injury.

EXPERIMENTAL DESIGN

We examined the pathophysiologic effect of ANCA on intracellular cytosolic-free calcium concentration (Ca2+)i in neutrophils by preincubating cells with ANCA-positive IgG or F(ab')2 preparations followed by stimulation with calcium ionophore (A23187). The mechanism by which ANCA may affect (Ca2+)i was studied by analyzing the production of platelet-activating factor (PAF), an intracellular messenger which is the mediator through which A23187 acts.

RESULTS

ANCA-positive F(ab')2 induced a small but insignificant increase in (Ca2+)i. Preincubation of neutrophils with ANCA-positive IgG or F(ab')2 reduced the calcium mobilization induced by subsequent stimulation with A23187 compared with experiments performed with antibody preparations from ANCA-negative disease or healthy controls. The suppression of A23187-induced calcium mobilization was dose-dependent and correlated with the serum ANCA levels at clinical presentation. ANCA did not bind PAF but reduced the binding of PAF to neutrophils, suggesting that ANCA may prevent the expression of PAF receptor on activated neutrophils. The preincubation of neutrophils with increasing concentrations of F(ab')2 preparation resulted in reduced membrane and supernatant concentrations of PAF, an effect that was more prominent with ANCA-positive F(ab')2.

CONCLUSIONS

Our data suggest ANCA may potentially mediate a pathophysiologic effect on neutrophils through interference with the signal transduction pathways utilized in neutrophils' activation. One of the possible mechanisms underlying the suppressive effect of ANCA on A23187-induced calcium mobilization may be mediated through the reduction of PAF synthesis.

Use of antineutrophil cytoplasmic autoantibodies in diagnosing vasculitis in a Chinese patient population

Antineutrophil cytoplasmic autoantibodies (ANCA) have been used as markers of systemic vasculitides, including microscopic polyarteritis (MPA) and Wegener's granulomatosis. The diagnostic potential of ANCA assays together with antibodies against the neutrophil enzymes myeloperoxidase (MPO) and proteinase 3 for detecting a systemic vasculitis was tested in a Chinese patient population. 672 sera were received for ANCA assay, and ANCA detected by indirect immunofluorescence was positive in 73 sera from 42 patients. Of the 42 patients, 3 had cytoplasmic ANCA, while 39 had a perinuclear pattern. There was no patient with Wegener's granulomatosis. Two cytoplasmic ANCA positive patients suffered from ulcerative colitis. Another cytoplasmic ANCA positive patient was a carrier of human immunodeficiency virus. Of the 39 perinuclear ANCA positive patients, 10 had MPA. Eight of them were tested for anti-MPO antibody, and all were positive. Other immune disorders that were perinuclear ANCA positive included: 13 patients with systemic lupus erythematosus, 3 with mixed connective tissue disease, 1 with Goodpasture's syndrome, 2 with inflammatory bowel disease, and 2 patients with IgA nephropathy. Anti-MPO antibody was not specific for MPA, and 7 out of the 13 patients with systemic lupus erythematosus were anti-MPO antibody positive. Our study suggests that ANCA and anti-MPO antibody are not specific for MPA in a Chinese population. They would alert the clinician of the possibility of vasculitis, but a clinicopathological correlation is essential in making the diagnosis.

Correction of anemia using self-administered daily subcutaneous erythropoietin in uremic patients on continuous ambulatory peritoneal dialysis

We studied the effects of self-administered, daily, low-dose, subcutaneous (SC) erythropoietin (EPO) therapy in 15 uremic patients on continuous ambulatory peritoneal dialysis (CAPD) for 16 weeks to assess its efficacy and safety. The patients had baseline hemoglobin (Hb) levels of < 8 g/dl and were started on 10 u/kg/day of beta-EPO. The dosage of EPO was adjusted every 4 weeks according to hematological response. The patients learned to inject into their thighs themselves. Hb increased significantly from 6.6 +/- 0.2 g/dl (mean +/- SEM) at week 0 to 9.0 +/- 0.3 at week 8 and 10.0 +/- 0.4 at week 16 (p < 0.0001). Hematocrit (Hct) increased significantly from 0.20 +/- 0.01 at week 0 to 0.27 +/- 0.01 at week 8 and 0.29 +/- 0.001 at week 16 (p < 0.0001). The mean EPO dose was 10 u/kg/day at week 0 and 10.5 +/- 0.4 at week 8 and 10.3 +/- 0.5 at week 16. After minor adjustments in antihypertensive therapy had been made no significant differences in mean arterial blood pressure were noted. Six of 15 patients required increased dosage of antihypertensive drugs. All patients were given oral iron supplements. There was a significant decrease in percentage of transferrin saturation and 10 patients required additional intravenous iron supplements. There was no significant difference in the serum levels of creatinine, albumin, potassium, phosphate and urate with EPO treatment. There were no local complications at the sites of injection and the injections themselves were quite painless.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum concentration of soluble interleukin 2 receptors in asthma. Correlation with disease activity

We evaluated whether serum soluble interleukin 2 receptor (sIL-2R), a marker of T lymphocyte activation in vivo, could be useful to monitor disease activity in asthma. Venous blood was collected from 26 patients with acute severe asthma prior to the commencement of systemic corticosteroid therapy (day 1), 15 with stable disease, and 13 normal control subjects. Serum sIL-2R level was significantly higher in acute asthma (462.7 +/- 36.1 U/ml; mean +/- SEM) than stable disease (328.5 +/- 30.4 U/ml, p = 0.013) which in turn, was significantly raised when compared with control subjects (239.0 +/- 22.9 U/ml; p = 0.0003 vs acute; p = 0.036 vs stable). Nevertheless, sIL-2R concentrations in 11 patients with acute and 11 with stable disease did not exceed the upper limit of normal, ie, mean +.2 SD of the value in control subjects = 404.4 U/ml. Repeated measurements of sIL-2R in 24 acute asthmatics on day 3 revealed no significant fall (464.6 +/- 37.2 U/ml, NS), although the reduction in sIL-2R was significantly correlated with the corresponding improvement in peak expiratory flow (r = -0.52, p = 0.005). Following resolution of the acute attack, further measurements performed in 11 of these subjects on day 28 showed a significant fall in sIL-2R (p = 0.016). Our data showed that although serum sIL-2R was raised in asthma and, to a certain extent, might reflect disease activity, the considerable overlap of values between asthma of differing severity and normal control subjects precludes its clinical use as an index of asthma severity.

Heat-aggregated IgA prepared from patients with IgA nephropathy increases calcium mobilization and superoxide production of human neutrophils in vitro

IgA nephropathy, characterized by predominant mesangial IgA deposition, is the commonest glomerulonephritis worldwide. It is envisaged that circulating IgA plays a primary role in the glomerular injury of IgA nephropathy. In this study, we examined the pathophysiologic effect of IgA and IgG isolated from IgA nephritic patients on the signal transduction and oxidative metabolism of human neutrophils. Heat-aggregated forms, monomers, and F(ab')2 fragments of IgA and IgG were prepared from sera of 11 IgA nephritic patients and 11 healthy controls. Signal transduction was studied by measuring calcium mobilization and oxidative metabolism by measuring superoxide production. Different forms of IgA and IgG from patients with IgA nephropathy did not induce a significant increase in calcium mobilization directly. Nonetheless, neutrophils preincubated with heat-aggregated IgA or IgG from IgA nephritic patients demonstrated a significant rise in calcium mobilization upon subsequent stimulation by a chemotactic peptide, FMet-Leu-Phe (FMLP). Heat-aggregated IgA or IgG pretreatment of neutrophils increased FMLP-induced calcium mobilization in a dose-dependent manner. Aggregated IgA or IgG prepared by heat aggregation from IgA nephritic patients induced a significantly greater superoxide production from neutrophils than immunoglobulins from healthy controls. Similarly, heat-aggregated IgA and IgG induced superoxide production in a dose-dependent manner. Our data suggest that heat-aggregated forms of IgA and IgG exert an upregulatory effect on signal transduction and oxidative metabolism in human neutrophils. These findings indirectly support the view that neutrophils could be activated in IgA nephropathy and may potentially be participating in the inflammatory process of glomerular and interstitial injury.

Pulmonary embolism from a popliteal vein aneurysm

This is the first report of a venous aneurysm detected by radionuclide venography. Aneurysms of the popliteal vein are very rare. Described here is a case of a saccular popliteal venous aneurysm that presented as dyspnea secondary to pulmonary embolism. In this case, there was recurrent PE despite anticoagulant therapy. Almost all such aneurysms are associated with PE, about half of which are recurrent. This report demonstrates another useful aspect of obtaining a simultaneous radionuclide venogram when performing a perfusion lung scan with Tc-99m MAA.

Characterization of cytokine gene expression in CD4+ and CD8+ T cells after activation with phorbol myristate acetate and phytohaemagglutinin

Cytokines are important mediators involved in the development of effector cells and in the regulation of immune responses. The gene expression of these mediators in T cell subset has yet to be fully elucidated. Using sensitive reverse transcription-polymerase chain reaction (RT-PCR), the kinetics of cytokine gene expression in human CD4+ and CD8+ T cells were examined. CD4+ T cells were more readily activated by phorbol myristate acetate (PMA) and phytohaemagglutinin (PHA) than CD8+ T cells in terms of the IL-2 receptor (IL-2R) mRNA expression. Quantitative differences in cytokine gene expression between CD4+ and CD8+ T cells were confirmed and higher levels of cytokine mRNAs were induced in CD4+ than in CD8+ T cells. Early induction of IL-2 mRNA was observed in both T cell subsets. The demonstration of different kinetics of cytokine gene expression illustrates one of the examples of the complexity of immunoregulation. The differential response of cytokine gene expression in different T cell subsets should be taken into consideration when clinical studies in cytokine production by peripheral blood mononuclear cells are interpreted.

Genomic analysis using a yeast artificial chromosome library with mouse DNA inserts

A yeast artificial chromosome library with mouse genomic DNA inserts has been constructed. The library encompasses a 2.5-fold coverage of the mouse genome, with an average insert size of 250 kilobases. The screening strategy uses the polymerase chain reaction on pooled DNAs prepared from individually stored clones. The usefulness of the library for chromosome walking was illustrated by constructing a 600-kilobase-long contig of DNA surrounding Hba-ps4, a DNA marker that is tightly linked to the fused (Fu) locus on chromosome 17.

Effects of alpha-interferon and prednisone on serum-soluble interleukin-2 receptor (sIL-2R) in chronic hepatitis B infection

The level of serum-soluble interleukin-2 receptor (sIL-2R) was measured in 32 patients to investigate the effect of prednisone and alpha-interferon therapy on chronic hepatitis B virus infection. All the patients were seropositive for hepatitis B surface antigen and hepatitis B e antigen, with histological evidence of chronic persistent or chronic active hepatitis. Twenty-six patients received oral prednisone, followed by subcutaneous recombinant alpha-interferon, and six patients received multivitamin tablets and served as controls. After 4 wk of prednisone in reducing dosage, serum sIL-2R fell significantly from 673.6 +/- 52.9 U/ml to 584.8 +/- 39.4 U/ml (mean +/- SE, p less than 0.05). It rose to 733.4 +/- 45.7 U/ml (p less than 0.05) on the 4th wk of interferon, but returned to pretreatment level at completion of interferon. There was a significant correlation between serum sIL-2R and alanine aminotransferase levels (r = 0.36, p less than 0.001). The level of serum sIL-2R before treatment and its response to prednisone and interferon were not useful in predicting seroconversion of hepatitis B e antigen and anti-hepatitis B e.

Cytokine production by peripheral blood mononuclear cells in IgA nephropathy

The regulation of cytokine production and T cell proliferation by other cytokines is mandatory in mediating inflammatory responses but the full understanding is far from complete. We have previously reported increased production of IL-2 and IL-2 receptors (IL-2R) in IgA nephropathy. The present study was undertaken to examine other cytokine production during T cell activation in IgA nephropathy. Peripheral blood mononuclear cells (PBMC) from 17 IgA nephritic patients and 14 controls were cultured with phytohaemagglutinin and phorbol myristate acetate for 48 h for maximal cytokine production. IL-2Rs and IL-4 receptors (IL-4Rs) expressed on cultured PBMC were studied by a radioimmunoassay using monoclonal antibodies against these receptors. Although the total cellular IL-2R expression and percentages of T helper and T suppressor cells did not differ between the patients and controls, there was a significant increase in activated T helper cells expressing IL-2R in patients with IgA nephropathy. The total cellular IL-4R expression was elevated in IgA nephritic patients (P less than 0.005). IL-2 production by PBMC was raised in IgA nephritic patients compared with controls (P less than 0.05) but no difference in IL-4 or IL-6 production was observed. The interferon-gamma production by PBMC was significantly increased in patients with IgA nephropathy (P less than 0.025). No correlation was observed between individual cytokine levels. Our data suggest there are selective increases in cytokine production in IgA nephropathy.