Biomedical subjects

G J Dobos

Publications and source records attributed to G J Dobos.

35 records · Page 2Linked to original sources

PubMed1997

Inverse MCP-1/IL-8 ratio in effluents of CAPD patients with peritonitis and in isolated cultured human peritoneal macrophages.

An important event in intraperitoneal inflammation is the influx of leukocytes into the peritoneal cavity. Chemokines such as interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) play a major role in the recruitment of immune cells to the site of inflammation. We determined the concentrations of two members of the chemokine family, IL-8 and MCP-1, in the dialysate effluents of 18 continuous ambulatory peritoneal dialysis (CAPD) patients with peritonitis and of 18 non-infected CAPD patients by specific enzyme-linked immunosorbent assays (ELISA). Isolated peritoneal macrophages (PMs) from CAPD peritonitis patients were cultured and IL-8 and MCP-1 production was determined on protein (ELISA) and mRNA level (Northern blot) at designated timepoints over a 72-h culture period. PMs from non-infected patients served as controls. Much higher concentrations of IL-8 and MCP-1 were found in dialysate effluents of peritonitis patients than in effluents of non-infected patients: IL-8 2.39 +/- 1.15 vs 0.05 +/- 0.01 ng/ml and MCP-1 22.5 +/- 6.27 vs 0.42 +/- 0.07 ng/ml. IL-8 and MCP-1 release by cultured PMs from peritonitis patients and non-infected patients revealed significant differences: IL-8 40.3 +/- 2.2 ng/ml after 3 h and 194.2 +/- 34.9 ng/ml after 12 h compared to 21.02 +/- 6.15 ng/ml after 3 h and 89.64 +/- 30.28 ng/ml after 12 h, respectively; MCP-1 3.3 +/- 0.9 ng/ml after 3 h and 25.7 +/- 7.4 ng/ml after 12 h compared to 1.1 +/- 0.2 ng/ml and 1.8 +/- 0.2 ng/ml, respectively. Interestingly, the ratio of IL-8 to MCP-1 concentrations in the dialysate effluents (1:9.4) is reversed in the supernatants of cultured PMs. In the effluents and in the culture supernatants of PMs from CAPD peritonitis patients high amounts of IL-8 and MCP-1 are detectable, suggesting that PMs are an important source for these chemokines during peritonitis. Because of the inverse ratio of IL-8 and MCP-1 in the effluents and culture supernatants it can be assumed that PMs are responsible for the MCP-1 concentration to a lesser extent than for the IL-8 concentration in the effluents.

Cells, Cultured↗

PubMed1997

Improved cytosolic free calcium mobilization and superoxide production in bicarbonate-based peritoneal dialysis solution.

BACKGROUND: Intraperitoneal phagocytes play an important role in local host defence to prevent CAPD peritonitis. The intracellular calcium [Ca2+]i is thought to be involved in the regulation of various cell functions. This study therefore investigates the effect of lactate-based dialysis solution (LBDS) and bicarbonate-based dialysis solution (BBDS) on cytosolic free calcium mobilization and superoxide production (SP) as important steps in signal transduction and bacterial killing. METHODS: We studied changes in [Ca2+]i and SP following stimulation with N-formyl-methionyl-leucyl-phenylalanine (fMLP) in polymorphonuclear neutrophils (PMNs) incubated in either LBDS-pH 5.2, LBDS adjusted to pH 7.4, 1:10 diluted spent and fresh LBDS or BBDS-pH 7.4 with different glucose concentrations, comparing the data with cells treated with Hanks buffer (HBSS) pH 7.4 as control. To elucidate the effect of glucose and lactate PMNs were additionally incubated in HBSS-pH 7.4, containing glucose (HBSS-Glu-pH 7.4) or lactate (HBSS-Lact-pH 7.4) in the same concentrations as contained in CAPD solutions and tested as above. PMNs were isolated from healthy blood donors and incubated with dialysis solution 10 min prior to stimulation with fMLP. RESULTS: [Ca2+]i mobilization and SP were completely inhibited in PMNs incubated in LBDS pH 5.2. pH adjustment of LBDS to 7.4 and 1:10 dilution of spent and fresh LBDS corrected some of the suppression of the calcium influx and superoxide production. BBDS pH 7.4, however, preserved physiological cell function significantly better at low (1.5 and 2.3%) glucose concentrations. CONCLUSION: In comparison to conventional lactate-based dialysis solution, pH adjusted and 1:10 diluted LBDS, bicarbonate-based dialysis solution is more biocompatible since it preserves significantly better neutrophil cell functions.

Bicarbonates↗

PubMed1997

Lipopolysaccharide binding protein: a marker for intraperitoneal bacterial infection in patients with CAPD peritonitis.

During systemic infection, the serum lipopolysaccharide binding protein (LBP) binds to the lipid A component of bacterial endotoxins and facilitates its delivery to the CD 14 receptor on the cell surface of macrophages, where proinflammatory cytokines are released. There is no knowledge to date whether LBP is also present in the effluent of patients with continuous ambulatory peritoneal dialysis (CAPD)-associated peritonitis. We investigated the dialysis effluent of 37 patients with CAPD peritonitis for immunoreactive LBP, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-1 beta and compared the findings with the cytokine levels in 20 noninfected CAPD patients. The mean +/- SEM concentrations of LBP, TNF-alpha, and IL-1 beta were significantly higher in the effluent of patients with peritonitis than in noninfected CAPD effluent. In comparison to controls (0.23 +/- 0.05 microgram/mL), LBP was 0.68 +/- 0.13 microgram/mL in the effluent of patients with CAPD-associated infectious peritonitis. For TNF-alpha, levels were 0.50 +/- 0.25 pg/mL in the control effluent versus 124.7 +/- 46.6 pg/mL in the effluent of peritonitis patients. For IL-1 beta the levels were 0.24 +/- 0.14 pg/mL in the control effluent and 71.23 +/- 17.53 pg/mL in the peritonitis patients. Our findings demonstrate that LBP is significantly elevated in the effluent of CAPD patients during an episode of CAPD-associated peritonitis and might be used as a marker of intraperitoneal bacterial infection.

Acute-Phase Proteins↗

PubMed1996

Actin polymerization in human eosinophils, unlike human neutrophils, depends on intracellular calcium mobilization.

Eosinophils represent major effector cells in the allergic inflammation. In contrast to neutrophils, the mechanism of eosinophil activation during the inflammatory response is poorly understood. In this study, the relation between calcium fluxes, chemotaxis, and actin polymerization in eosinophils from healthy non-atopic donors was investigated. Pre-incubation of eosinophils with the intracellular calcium chelator BAPTA dose-dependently prevented an increase in the intracellular calcium concentration ([Ca2+]i), whereas the depletion of extracellular calcium in the test medium had no effect. The chemotactic response of eosinophils, which was measured by the modified boyden chamber technique upon stimulation with RANTES, C5a and PAF, was dose-dependently inhibited by the chelation of intracellular calcium as well as inactivation of the cells in Ca2+ -depleted medium. To evaluate whether other cell functions which are involved in the migratory response of eosinophils might be dependent on intracellular and extracellular calcium, actin polymerization was investigated. Flow-cytometric measurement of F-actin with NBD-phallacidin revealed that actin polymerization in human eosinophils in response to RANTES, C5a, and PAF was dose-dependently inhibited by the intracellular calcium chelator BAPTA. Since it is well known that actin polymerization in neutrophils is not affected by chelation of intracellular calcium, actin polymerization in these cells was investigated under the same conditions as for eosinophils. In contrast to eosinophils, BAPTA did not inhibit actin polymerization in neutrophils. In summary, these data demonstrate that intracellular calcium fluxes represent a prerequisite for eosinophil chemotaxis and actin polymerization in human eosinophils. Furthermore, regulation of actin polymerization in eosinophils differed from that of neutrophils on the level of intracellular calcium fluxes.

Actins↗

PubMed1995

Synthesis and surface expression of ICAM-1 in polymorphonuclear neutrophilic leukocytes in normal subjects and during inflammatory disease.

During bacterial peritonitis of patients on continuous ambulatory peritoneal dialysis (CAPD) leukocytes, particularly polymorphonuclear neutrophilic granulocytes (PMNs), migrate into the peritoneal cavity. However, at the site of inflammation PMNs are not sufficiently able to protect the host against micro-organisms. Adhesion molecules, such as ICAM-1 (CD54), are involved in the interaction between endothelial cells and PMNs leading to the accumulation of PMNs at the site of inflammation. As PMNs are the predominant cell type in the peritoneal cavity in peritonitis, the aim of this study was to find out whether PMNs from CAPD peritonitis patients were able to express ICAM-1. Flow cytometric analyses with the anti-CD54 monoclonal antibody demonstrated that normal PMNs constitutively express slight amounts of ICAM-1. In contrast to normal PMNs, peritoneal PMNs from patients with CAPD peritonitis expressed high amounts of ICAM-1 (p = 0.003). Furthermore, ICAM-1 expression on peripheral blood PMNs of these patients significantly differed from PMNs from healthy donor (p = 0.01). Furthermore, Northern blot analysis revealed a weak signal of ICAM-1 mRNA in normal PMNs. However, peritoneal PMNs from CAPD peritonitis patients expressed a strong signal for ICAM-1 mRNA, suggesting that ICAM-1 is newly synthesized when PMNs invade the peritoneal cavity. In summary, this study clearly demonstrates that peritoneal PMNs of CAPD peritonitis express high amounts of ICAM-1 receptor on the level of mRNA and on the surface. Therefore, it is tempting to speculate that peritoneal PMNs interact amongst each other between ICAM-1 and its counter receptors CD11a,b/CD18 receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

CD11 Antigens↗

PubMed1995

MCP-1 levels are elevated in peritonitis fluid from CAPD patients due to secretion by peritoneal macrophages.

The migration of leukocytes, including polymorphonuclear neutrophils and monocytes, into the peritoneal cavity is a key event of intraperitoneal inflammation. We investigated the levels of two members of the chemokine family, interleukin 8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1), in the dialysate effluent of 18 continuous ambulatory peritoneal dialysis (CAPD) patients with peritonitis and compared them with chemokine levels in noninfected CAPD effluent. Being a major source of inflammatory cytokines, we also isolated peritoneal macrophages from peritonitis effluent to determine the mRNA expression directly after isolation. The mean (SEM) concentrations of IL-8 and MCP-1 were significantly higher in the effluent of peritonitis patients than in noninfected effluents MCP-1: 22.5 +/- (6.27) versus 0.37 +/- (0.1) ng/mL and IL-8: 2.39 +/- (1.15) versus 0.04 +/- (0.01) ng/mL. Northern blot analysis of isolated effluent macrophages revealed strong signals for MCP-1 and IL-8. Our findings showed that CAPD effluent from patients with peritonitis contains markedly elevated MCP-1 and IL-8 levels, suggesting that these chemokines participate in leukocyte recruitment during CAPD peritonitis. Isolation of mRNA of peritonitis-derived peritoneal macrophages revealed strong signals for MCP-1 and IL-8, suggesting that macrophages are a major source of these inflammatory mediators.

Ascitic Fluid↗

PubMed1994

[Unilateral diffuse pulmonary involvement in vasculitis with anti-neutrophil cytoplasmic antibodies and anti-glomerular basement membrane antibodies].

A previously healthy 51-year-old man, hospitalized because of fatigue and joint complaints, was found to have left-sided diffuse pulmonary infiltration and a rapid rise in creatinine concentration. Anti-neutrophil cytoplasmic antibodies (cANCA) and anti-glomerular basement antibodies (anti-GBM) were found in serum. Renal biopsy revealed extracapillary glomerulonephritis with diffuse half-moon formations. Immunohistology showed a diffuse granular pattern for immunoglobulin G, M and complement C3, without linear deposits. Immunosuppressive treatment combined with plasmapheresis brought about rapid clinical improvement and normalization of the lung involvement and renal function, as well as a fall in the cANCA titre. During a follow-up period of 5 years there has been no recurrence of symptoms, although the anti-GBM titre remained strongly positive and the cANCA titre twice rose to abnormal levels.

Antibodies, Antineutrophil Cytoplasmic↗

PubMed1994

Neutrophil dysfunction in end-stage renal failure: reduced response to priming by C5a.

We studied the effect of C5a pretreatment on phosphatidyl-inositol-4,5-bisphosphate (PIP2) hydrolysis and on the increase in peak and resting cytosolic calcium levels induced by C5a (0.1 and 10 nM) and/or N-formyl hexapeptide (FLPEP; 10 nM) in neutrophils isolated from patients with end-stage renal failure (ESRF) and those from healthy controls. We also investigated superoxide anion production under the same conditions using the fluorescent para-hydroxyphenylacetic acid assay. The hydrolysis of PIP2 induced by C5a or FLPEP alone was similar in neutrophils from patients with ESRF and in control cells. Likewise, pretreatment of patients' neutrophils with C5a prior to FLPEP did not affect hydrolysis or the increase in cytosolic calcium concentration as shown previously for control neutrophils. Resting calcium levels in both ESRF and control neutrophils, however, were significantly increased after priming with low C5a concentrations. After priming with low C5a, prior to FLPEP, there was also a significant increase in superoxide production. This increase was significantly lower in cells from uremic patients than in those from healthy controls. Our data suggest that priming-induced superoxide production in neutrophils is reduced in patients with ESRF.

Amino Acid Sequence↗

PubMed1994

Actin polymerization, calcium-transients, and phospholipid metabolism in human neutrophils after stimulation with interleukin-8 and N-formyl peptide.

Signal transduction of interleukin-8 (IL-8) was analyzed in neutrophils, and compared with the well known neutrophil activator N-formyl peptide. Stimulation of human neutrophils with IL-8 induced a rapid polymerization of actin as detected by 7-nitrobenz-2-oxa-1,3-diazol-(NBD)-phallacidin staining of f-actin and reduction of monitored right-angle light scatter. Actin polymerization peaked within 10 seconds after the addition of IL-8 and was short-lived as compared to N-formyl peptide-induced stimulation. Analysis of phospholipids by thin-layer chromatography and analysis of deacylation products of lipid extracts by high-pressure liquid chromatography (HPLC) showed that IL-8 triggered a rapid rise of [32P]phosphatidyl-inositol(3,4,5)trisphosphate (PtdInsP3) followed by a slower increase of [32P]phosphatidylinositol(3,4)bisphosphate (PtdIns-3,4-P2) along with a rapid decrease of [32P]phosphatidylinositol(4,5)bisphosphate (PtdIns-4,5-P2). Changes in polyphosphoinositide metabolism were more moderate and transient than those obtained by N-formyl peptide. Moreover, [32P]phosphatidic acid (PA) production stimulated by IL-8 was minimal and transient as compared to the response activated by N-formyl peptide. Both IL-8 and N-formyl peptide induced Ca++ mobilization from intracellular stores, but IL-8 in contrast to N-formyl peptide failed to trigger the secondary influx of Ca++ from the extracellular medium. In summary, IL-8 and N-formyl peptide stimulated similar and distinct patterns of intracellular activation steps. This study indicates that IL-8 is a potent activator of intracellular events presumably required for chemotaxis, but a relatively weak activator for events associated with superoxide anion generation and proinflammatory activity.

Actins↗

PubMed1994

Bicarbonate-based dialysis solution preserves granulocyte functions.

OBJECTIVE: Intraperitoneal phagocytes play an important role in local defense in preventing continuous ambulatory peritoneal dialysis (CAPD) peritonitis. This study therefore investigates the effect of the conventional lactate-based dialysis solution-pH 5.2 (LBDS-pH 5.2) and a bicarbonate-based dialysis solution (BBDS) on various cell functions. DESIGN: We studied C5a-induced actin polymerization (AP) as a measure of the cytoskeletal alteration, phagocytosis of zymosan particles, and chemotaxis in neutrophils incubated in either LBDS-pH 5.2, LBDS-pH 7.4, or BBDS-pH 7.4, comparing the data with cells treated with phosphate-buffered saline-pH 7.4 (PBS-pH 7.4) as a control. SUBJECTS: Polymorphonuclear neutrophils (PMNs) were isolated from the blood of healthy donors and incubated with dialysis solution prior to the experiment. RESULTS: C5a-induced AP was dramatically inhibited in PMNs incubated in LBDS-pH 5.2, paralleled by a complete inhibition of phagocytosis and C5a-induced chemotaxis. In comparison, BBDS improved AP to values above the control and also nearly normalized phagocytosis. Chemotaxis markedly improved in cells treated with the low glucose-containing BBDS (Bic 20), containing high glucose concentrations (Bic 30). CONCLUSION: In comparison with conventional lactate-based dialysis solution-pH 5.2, bicarbonate-based dialysis solution at low osmolality better preserves neutrophil functions that involve the cytoskeleton.

Actins↗

PubMed1993

A product of phosphatidylinositol-3 kinase is elevated in dividing HT29 colonic epithelial cells.

Phosphatidylinositol 3 kinase (PI-3 kinase) activity has been linked to cell proliferation and growth regulation. Therefore, we studied changes in phosphoinositide metabolism during the cell cycle of HT-29 cells, a colonic epithelial cell line. HT29 cells were treated with the microtubule disrupter, nocodozole, separated into mitotic and quiescent populations and their phospholipid composition was analyzed. Radiolabelled phospholipids from cells labelled with 32PO4 or [3H]myoinositol were analyzed by TLC and/or deacylated and analyzed by HPLC. In all cases, levels of phosphatidylinositol 3 phosphate from mitotic phase cells were double that in resting populations. Therefore, levels of a product of PI-3 kinase are elevated and may play a role in cell division.

Cell Adhesion↗

PubMed1993

Flow cytometry reveals different lag times in rapid cytoplasmic calcium elevations in human neutrophils in response to N-formyl peptide.

Flow cytometric analyses were performed to study intracellular single-cell calcium transients ([Ca2+]i) in suspended human neutrophils during the initial phase of N-formyl peptide stimulation. Thereby, two neutrophil populations became apparent. Early maximally Ca(2+)-responding (high fluorescence) neutrophils and not-yet Ca(2+)-responding (low fluorescence) neutrophils, but no neutrophils with intermediate levels of [Ca2+]i were detected. Within 7 s the number of low fluorescence neutrophils decreased and the number of high fluorescence neutrophils increased maximally. This suggests that [Ca2+]i transients occurred abruptly in individual neutrophils within a time interval below 1 s. At lower N-formyl peptide concentrations the lag times of individual neutrophils and the interval time of maximal activation of the [Ca2+]i-responding neutrophil population increased, however the percentage of [Ca2+]i-responding cells decreased. Surprisingly, no influence of the N-formyl peptide concentration on the [Ca2+]i-induced fluorescence signal of the individual cell was observed: it was always in an almost maximal range or not responding. In parallel, binding studies performed with fluorescein-labeled N-formyl peptide revealed that the heterogeneity of [Ca2+]i-responding cells cannot be explained by different receptor occupancy. In summary, this study demonstrates that [Ca2+]i transients induced by N-formyl peptides in suspended individual human neutrophils occur very rapidly in an almost "all-or-none manner" and that the mean increasing fluorescence signal of a calcium indicator within a whole neutrophil population results from varying lag times of the individual cells, rather than from the mean simultaneous progress of many cells.

Calcium↗

PubMed1993

Inhibition of C5a-induced actin polymerization, chemotaxis, and phagocytosis of human polymorphonuclear neutrophils incubated in a glucose-based dialysis solution.

Chemotaxis and phagocytosis are important functions of phagocytic cells, which are closely related to cytoskeletal reorganization. These functions may be abnormal in phagocytes of uremic patients undergoing continuous ambulatory peritoneal dialysis (CAPD). In order to examine whether these abnormalities result from treatment, we studied actin polymerization (AP), as an index of cytoskeletal alterations, chemotaxis, and phagocytosis in polymorphonuclear neutrophils (PMNs) of healthy subjects. Polymorphonuclear neutrophils were exposed to either a hepes buffer or a glucose-based dialysis solution (GBDS) of different pH's (5.2, 7.4) and different glucose concentrations (1.36%, 2.27%, 3.86%). After incubation for 0, 5, or 20 minutes, cells were activated with 10 nmol/L C5a-complement. AP was measured as filamentous (F) actin content by NBD phallacidin staining and FACS analysis. Chemotaxis of PMNs was measured in Boyden chambers. In addition, phagocytosis of zymosan particles was assessed. Prior exposure to GBDS pH 5.2 of each glucose concentration immediately and completely inhibited AP in response to 10 nmol/L C5a-complement, reduced chemotaxis (> 95%), and completely inhibited phagocytosis. The inhibition was pH-dependent, since GBDS pH 7.4 caused less inhibition of these functions. We conclude that glucose-based dialysis solutions are cytotoxic towards neutrophils and completely inhibit their ability to display responses requiring cytoskeletal reorganization.

Actins↗

PubMed1993

[Unilateral blindness in neurosyphilis].

A 55 year-old patient developed loss of vision in his right eye over a period of a few weeks with the clinical finding of uveitis and papillaedema. Subsequently, also the left eye was affected by a marked deterioration of vision. The neurological findings were normal. The laboratory findings showed a marked elevation of the ESR (> 100 mm within the first hour) and protein electrophoreses showed changes suggestive of chronic inflammation. Analysis of the cerebrospinal fluid revealed a lymphocytic meningitis with 180/3 cells; the positive serological and liquor findings for TPHA and FTA led to the definite diagnosis of neurosyphilis. Treatment intravenously with 3 x 4 million units penicillin G daily for a fortnight proved curative. Vision of the left eye recovered fully, but the ophthalmological changes in the right eye were irreversible. This case shows that even today the differential diagnosis of syphilis must be considered with loss of vision of doubtful aetiology and uveitis.

Blindness↗

PubMed1992

C5a reduces formyl peptide-induced actin polymerization and phosphatidylinositol(3,4,5)trisphosphate formation, but not phosphatidylinositol (4,5) bisphosphate hydrolysis and superoxide production, in human neutrophils.

We investigated phospholipid signal transduction, calcium flux, O2- anion production and actin polymerization after stimulation with the C fragment and chemoattractant, C5a, and then determined how C5a pretreatment affected subsequent responses to formyl peptide in human neutrophils. We have previously demonstrated that the novel lipids, phosphatidylinositol trisphosphate (PIP3) and phosphatidylinositol(3,4)P2 (PI(3,4)P2), rise transiently in neutrophils after activation with formyl peptide. Furthermore, the rise in PIP3 parallels actin polymerization. In this study, neutrophils activated with C5a exhibited two distinct G protein-dependent signal pathways involving different phosphoinositides: 1) [32P]PI(4,5)P2 hydrolysis and [32P]PA production, and 2) the transient formation of D-3-phosphorylated phosphoinositides, [32P]PIP3 and [32P]PI(3,4)P2. When neutrophils were preincubated with C5a for 5 min before stimulation with formyl peptide, [32P]PI(4,5)P2 hydrolysis was unchanged, and [32P]PA production and O2- formation were slightly enhanced compared with controls stimulated with formyl peptide in the absence of C5a. In contrast, [32P]PIP3 production, right angle light scatter, and actin polymerization were all reduced 35 to 40%. Therefore, these data support the hypothesis that PIP3 plays a role in chemotaxis but not superoxide formation.

Actins↗

PubMed1990

Successful therapy of meningococcal sepsis in acute disseminated lupus erythematosus with plasmapheresis, immunosuppression, and antibiotics.

A 17-year-old female with a 5-year history of disseminated lupus erythematosus has remained without immunosuppressive therapy for the last 3 years. She was admitted to the hospital for acute abdominal pain, generalized edema, and rapidly developing dyspnea and somnolence. Although all symptoms were consistent with active SLE, septicemia was suspected because of leukocytosis (20,000/microliters), greatly elevated C-reactive protein (45 mg/dl), and normal complement values (C3 0.74 g/l, C4 0.21 g/l). Directly after bacterial blood cultures were prepared, a combined treatment was instituted consisting of plasmapheresis (3 x 2.1 l against fresh frozen plasma), antibiotics, prednisolone, and cyclophosphamide following the last plasmapheresis. Within three days cerebral function returned to normal, edema improved, and CRP fell to 0.5 mg/dl. The blood cultures and pericardial effusion displayed meningococcal colonies.

Adolescent↗

PubMedDate not supplied

Persistent inhibition of neutrophil function by glucose based dialysis solutions.

Local defense mechanisms play an important role in prevention of peritonitis, a major complication of continuous ambulatory peritoneal dialysis (CAPD) therapy. The authors have shown that hypertonic, lactate containing glucose based dialysis solutions (GBDS) used in CAPD lead to an immediate and complete pH-dependent inhibition of actin polymerization and phagocytosis in polymorphonuclear neutrophils (PMN) in vitro. Earlier studies have shown that the pH of the fluid equilibrates from 5.2 to approximately 6.4 during the first 30 min of intraperitoneal dwell time. Thus, the authors designed the current study to determine whether the inhibition of cytoskeletal function and intracellular acidosis induced by acidic solutions are reversed by this pH adjustment. To this end, actin polymerization, phagocytosis, and intracellular pH were studied in PMN isolated from healthy human donors during a 10 min incubation in commercially available GBDS at pH 5.2 and again after pH adjustment to 6.4. Actin polymerization was assessed by measuring F-actin content using NBD phallacidin staining and fluorescence activated cell scanner analysis. Phagocytosis was assessed using zymosan particles, and intracellular pH was monitored by spectrofluorometry. The impairment of cytoskeletal alterations in cells exposed to GBDS at pH 5.2 was persistent and not fully reversed by adjusting the pH. Likewise, phagocytosis remained markedly inhibited and intracellular pH did not rise after adjustment of pH. Thus, the results demonstrate a persistent cytotoxic effect of CAPD solutions on human phagocytes. The authors think that CAPD solutions must be modified to provide a more physiologic pH environment for proper phagocyte function.

Actins↗