Kar Neng Lai

Dialysate cell population and cancer antigen 125 in stable continuous ambulatory peritoneal dialysis patients: Their relationship with transport parameters

We investigated the total cell count and cell population of the overnight peritoneal dialysis effluent (PDE) by flow cytometry in 76 stable continuous ambulatory peritoneal dialysis (CAPD) patients. The mean percentage of mesothelial cells and macrophages was 4.4% and 57%, respectively. A higher percentage of dead cells among the mesothelial cells compared with other cell populations in the PDE was observed. Peritoneal transport properties were studied in every patient by determining the dialysate to plasma ratio of creatinine concentration (D/P) at the fourth hour of the peritoneal equilibration test, and the mass transfer area coefficient of creatinine (MTACCr) or glucose. Cancer antigen 125 (CA125), suggested as a bulk marker for the mesothelial mass in stable peritoneal dialysis patients, was determined in the PDE. No correlation was demonstrated between CA125 and the number of mesothelial cells, lymphocytes, or macrophages in the PDE. A significant correlation was observed between CA125 and different parameters of peritoneal transport (D/P and MTACCr). On the contrary, neither the history of peritonitis nor the duration of CAPD appeared to affect the CA125 concentration in the PDE. The lack of correlation between CA125 in the PDE and the duration of CAPD may be related to the early loss of peritoneal transport properties as a result of the use of hypertonic dialysate in the majority of our patients with small-volume CAPD (3 x 2 L daily exchange). Our findings suggest that CA125 may not necessarily correlate well with the number of mesothelial cells in PDE. In patients with vanishing of the mesothelial layer, the measurement of CA125 (as a bulk marker for the mesothelial mass in the peritoneum) may reflect the change of peritoneal transport properties.

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‐1β and interleukin‐6, and mRNAs encoding for interleukin‐1α 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‐1β and interleukin‐1α mRNA in endothelial cells incubated with anti‐dsDNA. The supernatant interleukin‐1β and interleukin‐6, and mRNAs encoding for interleukin‐1α 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.

T-lymphocyte activation in IgA nephropathy: Serum-soluble interleukin 2 receptor level, interleukin 2 production, and interleukin 2 receptor expression by cultured lymphocytes

The present study was undertaken to examine the T-lymphocyte activation in IgA nephropathy. Serum-soluble interleukin 2 receptor (sIL2R) levels were studied in 29 IgA nephritic patients, 17 patients with chronic glomerulonephritis (non-IgA nephropathy), and 30 healthy controls during an infection-free period. No difference in serum sIL2R level was demonstrated among these three groups of subjects. However, the serum sIL2R levels of IgA nephritic patient rose significantly during clinical exacerbation with synpharyngitic macroscopic hematuria and the serum sIL2R levels fell when hematuria subsided. Mitogen-stimulated cellular interleukin 2 receptor (IL2R) expression, sIL2R release, and interleukin 2 (IL2) production were also examined in peripheral blood mononuclear cells (PBMC) cultured for 24–48 hr in 21 patients with IgA nephropathy, 17 patients with chronic glomerulonephritides, and 17 healthy controls. The total cellular IL2R expression and sIL2R release did not differ among these three groups of subjects. However, the individual T-cell subsets bearing IL2R were distinctly different between IgA nephritic patients and the other two groups of controls. IgA nephritic patients had increased activated CD4+ lymphocytes and reduced activated CD8+ lymphocytes. Furthermore, IL2 production in response to phytohemagglutinin and pokeweed mitogen stimulation was increased in lymphocytes from patients with IgA nephropathy. The IL2 production did not correlate with the quantities of cellular and sIL2R yet the cellular IL2R expression paralleled the sIL2R released by cultured lymphocytes. Our present study suggests that the T lymphocytes from patients with IgA nephropathy have a defect in overproduction of IL2 and increased activated T helper-cell subset upon mitogenic stimulation. Serum measurement of sIL2R could potentially be useful in monitoring the disease activity.

Soluble interleukin-2 receptors in patients with nasopharyngeal carcinoma

The authors performed a retrospective analysis of serum soluble interleukin‐2 receptor (sIL‐2R) levels in 72 patients with nasopharyngeal carcinoma (NPC) using an enzyme immunoassay. Their objectives were to determine the value of serum sIL‐2R in estimating the tumor burden, and its predictive value in response to therapy and prognosis. The data showed that serum sIL‐2R levels in patients were significantly higher than that of healthy controls. The serum levels correlated with clinical staging and hence the tumor burden of NPC. Serial measurement of serum sIL‐2R provided an accurate prognostic index of the clinical response to radiotherapy in at least 89% of patients with raised serum sIL‐2R at initial diagnosis (defined as mean + 2 SD of healthy controls) and a reliable predictive index in all patients who subsequently developed distant metastasis despite initial radiotherapy. Simultaneous measurement of Epstein–Barr virus‐related serology (IgA‐VCA and IgG‐EA) failed to demonstrate predictive value comparable with that of serum sIL‐2R. The authors conclude that monitoring serum sIL‐2R levels has clinical and prognostic significance in patients with NPC and that prospective studies are indicated.

Effect of Subcutaneous and Intraperitoneal Administration of Recombinant Human Erythropoietin on Blood Pressure and Vasoactive Hormones in Patients on Continuous Ambulatory Peritoneal Dialysis

The effect of subcutaneous and intraperitoneal administration of recombinant human erythropoietin (rHuEPO) on blood pressure was evaluated in 20 patients with renal failure on continuous ambulatory peritoneal dialysis. The two groups of patients were commenced on a 16-week course of twice weekly rHuEPO by either the subcutaneous (10 patients) or the intraperitoneal route (10 patients). One patient in the latter group was subsequently excluded because of operation and transfusion. The hemoglobulin increased significantly from 6.9 +/- 0.3 g/dl to 9.8 +/- 0.6 g/dl after subcutaneous rHuEPO treatment (p less than 0.01) at an average dose of 84 +/- 9 U/kg body weight/week. For the intraperitoneal group, despite a higher average rHuEPO dosage (133 +/- 7 U/kg body weight/week), the hemoglobin level was not significantly altered (7.0 +/- 0.4 g/dl to 8.0 +/- 0.4 g/dl, p less than 0.05). During the 16-week period of rHuEPO therapy, an increase in antihypertensive therapy was required more frequently in patients in the intraperitoneal group but the difference between groups failed to reach statistical significance. There was no conclusive evidence that the rise in hematocrit was an independent precipitant of hypertension. Patients who were hypertensive prior to rHuEPO therapy appeared most susceptible to the pressor effects in that 8 of 11 treated hypertensive patients required more intensive antihypertensive treatment during EPO administration whereas none of the untreated patients developed hypertension during the study (Fishers exact test, p = 0.007). Plasma levels of the vasoactive hormones, atrial natriuretic peptide (ANP), plasma renin activity (PRA), and endothelin (ET) remained unchanged during both subcutaneous and intraperitoneal rHuEPO therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of low-dose low molecular weight heparin in hemodialysis☆

We investigated the lowest effective dosage of low molecular weight (LMW) heparin for hemodialysis in comparison to unfractionated (UF) heparin. Initial hemodialysis sessions were undertaken in 10 uremic patients with UF heparin of the dose habitually required for each patient. Four-hour hemodialysis sessions were then undertaken with LMW heparin (nadroparin) in a single bolus (200 anti-Xa unit Institut Choay/kg [aXaU IC/kg], 175 aXaU IC/kg, 150 aXaU IC/kg, or 125 aXaU IC/kg; two sessions for each dosage). Anti-Xa levels and activated partial thromboplastin time (APTT) were monitored hourly during dialysis. Fiber bundle volume of dialyzer was measured before and after dialysis. Urea clearance was determined at the onset and completion of dialysis. There were no episodes of excessive bleeding, clotting of dialyzers, or clots in air traps with UF heparin or LMW heparin. A 35% increase in APTT above baseline was observed in all dialysis sessions 1 hour after LMW heparin bolus, but the APTT decreased rapidly thereafter. The anti-Xa levels exceeded 0.5 U/mL for all sessions using LMW heparin irrespective of the dosage. No significant reduction of urea clearance was found in dialysis with either UF or LMW heparin. No reduction of fiber bundle volume of dialyzer was observed in dialysis with either UF or LMW heparin, although a small reduction (3%) was observed in dialysis with LMW heparin at 125 aXaU IC/kg. We concluded that the use of LMW heparin for hemodialysis is safe and effective as compared with UF heparin. The lowest effective dosage can be reduced to 125 aXaU IC/kg in high-risk patients to reduce hemorrhagic complications.

The clinicopathological characteristics of IgA nephropathy in Hong Kong

&NA; The clinicopathologic data of 237 Chinese patients with IgA nephropathy from Hong Kong are reviewed in an attempt to identify the features pertinent to Chinese patients. Although the nephropathy is commonest in the 26–35 year age group, 11% of the IgA nephritic patients were children below 16 years. The male predilection reported in Caucasian populations is not observed and the male:female ratio is 0.94 in our series. The commonest renal manifestation is microscopic hematuria (25%) and 19% of the patients present with macroscopic hematuria, not infrequently synpharyngitic. Nephrotic syndrome occurs in 15% of our patients and proteinuria more than 1 gm/day is documented in 58% of these IgA nephritic patients. The degree of proteinuria does not correlate with prognosis. A small proportion of these nephrotic patients respond to steroid therapy, suggesting a variant of IgA nephropathy that resembles lipoid nephrosis in its steroid‐responsiveness. Seventeen percent of the patients (18/104) are hepatitis B virus carriers and 61% of these patients demonstrate viral antigens in their renal biopsies, indicating that hepatitis B virus infection may sometimes play a pathogenetic role.

Replication of hepatitis B virus with corticosteroid therapy in hepatitis B virus related membranous nephropathy

The therapeutic effect of corticosteroid in hepatitis B virus (HBV) related membranous nephropathy was investigated in a 29-year-old chronic HBV carrier. Prednisolone (60 mg/day) was given for eight weeks and gradually reduced over the subsequent four months. In the renal biopsies taken before and after corticosteroid therapy, light microscopy revealed progression of sclerosis. Immunofluorescent staining showed glomerular capillary deposition of hepatitis B core antigen (HBcAg) by polyclonal antisera and hepatitis B e antigen (HBeAg) by monoclonal antibodies. Electron microscopy revealed 40–50 nm diameter virus-like particles in the glomeruli only from the biopsy performed after corticosteroid therapy. The serum concentrations of alanine aminotransferase, HBeAg, and HBV DNA increased with corticosteroid therapy suggesting active viral replication despite the absence of overt clinical hepatitis. Renal function did not improve and corticosteroid therapy was apparently not helpful in this patient. Our results conflict with the earlier notion that short-term corticosteroid does not interfere with a favorable outcome of the infection of the related renal disease.

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).

Soluble interleukin 2 receptor release, interleukin 2 production, and interleukin 2 receptor expression in activated T-lymphocytes in vitro

Summary Following activation in vitro, peripheral blood mononuclear cells (PBMC) express cell‐associated interleukin‐2 receptors (IL2R). The present study was undertaken to define the proportion of T lymphocyte subsets that express the IL2R (CD25 antigen) upon different mitogenic stimulation. Double immunofluorescence staining with different fluorochromes, fluorescein isothiocyanate and phycoethyrin, was applied for identification of IL2R positive cells and individual lymphocyte subset. The exact percentage of individual activated lymphocyte subset bearing IL2R was enumerated by photographic counting. There was paucity of IL2R in freshly isolated, unstimulated peripheral blood, PBMC cultured without mitogen, and cultured B lymphocytes. Following poke‐weed mitogen stimulation in vitro, 19% of CD4 (T‐helper/inducer) lymphocytes and 14% of CD8 (T‐suppressor/cytotoxic) lymphocytes expressed IL2R. Similarly, 25% of CD4 lymphocytes and 19% of CD8 lymphocytes expressed IL2R following phytohemag‐glutinin stimulation in vitro. Contrary to the reported data of Tac‐positive cells in human lymphoid tissues, our study revealed that, upon lectin mitogen stimulation, approximately 55% of IL2R positive PBMC were CD4 lymphocytes, and 45% of them were CD8 lymphocytes. These observations imply the plausible notion that interleukin‐2 mediated immune activation of T lymphocytes in PBMC is different from that in local lymphoid organs. It was also demonstrated that the release of soluble IL2R (sIL2R) and IL2 production in supernatant from cultured PBMC varied with different lectin stimulation. A significant correlation was demonstrated between the cellular and soluble IL2R but the production of IL2 from activated mononuclear cells bore no good correlation with either the cellular IL2R expression or the release of SIL2R.