A specific inhibitor of complement (C5)-derived chemotactic activity in serum from patients with systemic lupus erythematosus

Elastase controls the binding of the vitamin D-binding protein (Gc-globulin) to neutrophils: a potential role in the regulation of C5a co-chemotactic activity

The vitamin D-binding protein (DBP) binds to the plasma membranes of numerous cell types and mediates a diverse array of cellular functions. DBP bound to the surface of leukocytes serves as a co-chemotactic factor for C5a, significantly enhancing the chemotactic activity of pM concentrations of C5a. This study investigated the regulation of DBP binding to neutrophils as a possible key step in the process of chemotaxis enhancement to C5a. Using radioiodinated DBP as a probe, neutrophils released 70% of previously bound DBP into the extracellular media during a 60-min incubation at 37 degrees C. This was suppressed by serine protease inhibitors (PMSF, Pefabloc SC), but not by metallo- or thiol-protease inhibitors. DBP shed from neutrophils had no detectable alteration in its m.w., suggesting that a serine protease probably cleaves the DBP binding site, releasing DBP in an unaltered form. Cells treated with PMSF accumulate DBP vs time with over 90% of the protein localized to the plasma membrane. Purified neutrophil plasma membranes were used to screen a panel of protease inhibitors for their ability to suppress shedding of the DBP binding site. Only inhibitors to neutrophil elastase prevented the loss of membrane DBP-binding capacity. Moreover, treatment of intact neutrophils with elastase inhibitors prevented the generation of C5a co-chemotactic activity from DBP. These results indicate that steady state binding of DBP is essential for co-chemotactic activity, and further suggest that neutrophil elastase may play a critical role in the C5a co-chemotactic mechanism.

Long-term treatment with GM-CSF in patients with chronic lymphocytic leukemia and recurrent neutropenic infections

In this prospective study we evaluated the multiple effects of long-term GM-CSF therapy on blood counts, granulocyte functions and disease progression in patients with chronic lymphocytic leukemia (CLL) with chronic neutropenia and recurrent bacterial infections. The treatment duration varied from 2 to 12 weeks. The neutrophil count was raised in all patients, by the median of 6.6-fold. The neutrophil level of 1.0 x 10(9)/l was usually reached after two weeks. The initial dose of GM-CSF was 5 microg/kg/day, and 1-7 microg/kg/day was required to maintain the neutrophil level above 1.0 x 10(9)/l. Granulocyte functions, i.e. chemiluminescence (CL), random migration, and fMLP-stimulated chemotaxis were initially depressed in all patients when compared to healthy controls. GM-CSF enhanced significantly CL even when given at small doses (less than 1 microg/kg/day), even lower than the dose required to promote granulopoiesis. We conclude that GM-CSF is effective in improving CLL associated chronic neutropenia and also enhances impaired granulocyte chemiluminescence. Thus, GM-CSF could be helpful for giving chemotherapy without neutropenic delays and for prophylaxis of infectious complications in CLL patients.

Infection in systemic lupus erythematosus

The improved survival of SLE patients since the 1950s is the result of not only better treatment, but also supportive treatment of renal failure and the wealth of antibiotics now available. Ironically, the wider use of immunosuppressives, especially the alkylating drugs, and the longer survival of patients with renal insufficiency and renal failure have made the identification and appropriate treatment of infection in SLE an ongoing challenge.

Functional abnormalities in granulocytes predict susceptibility to bacterial infections in chronic lymphocytic leukaemia

Leukocyte functions were studied in 22 patients with chronic lymphocytic leukaemia (CLL) and were related to the patients' susceptibility to infections. In CLL patients with a history of infections, compared with CLL patients without infections or healthy controls, there were significant impairments of most granulocyte functions; random migration, N-formyl-methionylleucylphenylalanine (fMLP) and C5a stimulated chemotaxis and chemiluminescence response were decreased. No differences in these functions between CLL patients without infections and healthy controls were observed. Phagocytosis and intracellular killing of granulocytes were intact in all patients with CLL. By univariate analysis, neutrophil count and serum IgG level also predicted susceptibility to infections. By multivariate analyses, granulocyte chemotaxis and chemiluminescence remained as statistically significant predictors of infections. The lymphocyte functions (mitogen-induced lymphocyte proliferation and immunoglobulin production in vitro) were equally impaired in all patients with CLL and differed significantly from the respective functions in healthy control subjects. We conclude that impairments in granulocyte functions contribute to susceptibility to infections in CLL.

Polymorphonuclear leukocyte chemotaxis induced by zinc, copper and nickel in vitro

Metallic dental restorations and prosthetic constructions are susceptible to corrosion in oral environment, resulting in the release of various heavy metal ions. Chloride salts of zinc, copper, nickel, chromium, iron and gold were tested for their ability to promote the migration of polymorphonuclear leukocytes (PMNs). Using a modified Boyden chamber assay for chemotaxis zinc, copper and nickel enhanced the migration of PMN cells in concentration range of 0.5-1.0 mM, whereas no augmentation in migratory activity was noted using chromium or iron. In contrast, an inhibition in migratory activity was observed in cells directed toward gold ions. Exposure of cells to zinc, copper or nickel ions induced an orientation reaction in leukocytes in a similar fashion as the polarization reaction induced by a potent peptide chemoattractant, N-formylmethionylleucylphenylalanine (fMLP), in these cells. Exposure of PMN cells to zinc or nickel in chemotactic concentrations stimulated the chemotaxis of these cells to fMLP 2-fold, whereas pretreatment of the cells with zinc prior to assay markedly decreased the subsequent chemotactic migration of the cells to this metal or to fMLP. The enhanced locomotion of PMN cells induced by zinc, copper or nickel ions was found to be in greater extent due to an increase in directed migration (chemotaxis) rather than an augmentation in random movement (chemokinesis) as assessed by Zigmond-Hirsch checkerboard analysis. These results suggest that zinc, copper and nickel ions attract leukocytes by inducing and promoting the chemotactic response in these cells, which may modulate the inflammatory response of host tissue around such metals.

Invasive aspergillosis in systemic lupus erythematosus

Invasive aspergillosis is seldomly described in systemic lupus erythematosus. We present two cases of aspergillosis and review 21 cases reported between 1957 and 1994. The typical clinical presentation is fever and cough in a hospitalized SLE patient previously treated with corticosteroids, immunosuppressors, and broad-spectrum antibiotics. Unlike aspergillosis in other conditions, granulocytopenia is uncommon. Chest radiographs show diffuse or patchy infiltration of lung fields. Diagnosis was suspected premortem in 2 patients. Aspergillus fumigatus was identified or isolated in sputum or parenchimal tissues in the majority of cases. Twenty-two patients died (95%). The finding of hyphae in the sputum of a systemic lupus erythematosus patient with a suggestive clinical picture should lead to bronchoscopy, bronchoalveolar lavage, and lung biopsy. Proof of diagnosis will come from the demonstration of hyphae in tissues and isolation of aspergillus from tissue cultures. Long-term therapy with amphotericin B alone or in combination with fluorocytosine or itraconazole may help improve survival.

Defective polymorphonuclear leukocyte formyl peptide receptor(s) in juvenile periodontitis

Juvenile periodontitis (JP) is a disease characterized by severe gingival infections. PMN from some JP patients exhibit abnormal chemotactic responsiveness when challenged with the synthetic formyl peptide, FMLP. While investigating PMN function in JP, we found a patient in whom abnormal PMN chemotactic responses to FMLP were associated with a defective population of PMN formyl peptide receptor(s) (FPR). JP PMN failed to respond chemotactically when challenged with FMLP, but exhibited normal chemotactic responses upon exposure to purified human C5a. Furthermore, JP PMN were capable of degranulating and generating superoxide anion radicals as well as normal PMN upon exposure to FMLP. Binding studies demonstrated that JP PMN had a diminution in the number of high-affinity FPR. Studies in which FPR was radiolabeled by chemical cross-linking demonstrated that JP PMN FPR exhibited the same molecular weight and N-linked glycosylation as normal PMN FPR. JP PMN FPR, however, was more resistant to papain cleavage than normal PMN FPR. Autoradiograms obtained from 2D-PAGE of normal and JP PMN FPR demonstrated decreased amounts of FPR isoforms in JP PMN.

Iron mediates production of a neutrophil chemoattractant by rat hepatocytes metabolizing ethanol

Ethanol metabolism in hepatocytes is accompanied by release of a potent lipid chemoattractant for neutrophils. Production of the factor may initiate the inflammation associated with alcoholic hepatitis. In previous studies with a cytosol system from liver, production was blocked by iron chelators as well as by catalase and superoxide dismutase, suggesting the involvement of oxyradicals in formation of the chemoattractant. These studies have examined the role of iron in intact hepatocytes using cells from rats fed an iron-deficient diet, a control diet or a diet containing 3% carbonyl iron. The iron content averaged 1.4 nmol/mg protein in iron-deficient cells, 6.3 in controls and 135.3 in iron-loaded cells. Hepatocytes from all groups were established in primary culture and incubated with ethanol (10 mM); the medium was assayed for chemoattractant activity for human neutrophils. Cultures from chow-fed or iron-loaded animals produced chemoattractant as previously reported. By contrast, chemoattractant production was undetectable in the iron-deficient cultures. Addition of ferric citrate (10 microM) restored chemoattractant production while increasing cellular iron in the deficient cells less than 50% (to 2.3 nmol/mg protein). Addition of desferrioxamine mesylate to cultures of iron-loaded cells ablated chemoattractant production. The data provide evidence for the importance of hepatocellular iron in production of this alcohol-related lipid chemoattractant and suggest that a small intracellular pool of "free" iron plays a critical role.

Functional loss of chemotactic factor inactivator in the adult respiratory distress syndrome

The adult respiratory distress syndrome (ARDS) is often characterized by a neutrophilic alveolitis, which may be mediated in part by the neutrophil chemoattractant, C5a. Chemotactic factor inactivator (CFI) can decrease C5a-directed neutrophil chemotaxis. Thus, a loss of CFI activity in the ARDS lung could lead to an increased ability of C5a to attract neutrophils. Lung CFI levels were measured antigenically and functionally in bronchoalveolar lavage (BAL) fluid obtained from 29 patients with ARDS and in 14 normal control subjects. Antigenic levels of CFI were found to be markedly elevated in ARDS BAL fluid (1,855 +/- 437 ng/ml) compared with that in normal BAL (29 +/- 10 ng/ml, p less than 0.005), but, in contrast, CFI functional activity was markedly decreased in ARDS BAL fluid compared with that in normal BAL fluid (31 +/- 7% inhibition versus 76 +/- 5% inhibition, p less than 0.01). Furthermore, although purified CFI readily inhibited the ability of C5a to attract neutrophils (92% inhibition), this activity was decreased when BAL fluid from patients with ARDS was incubated with CFI (47 +/- 10%, p less than 0.01). These findings suggest that patients with ARDS are functionally deficient in CFI, leading to an increased ability of C5a to attract neutrophils.

Identification of an IgA inhibitor of neutrophil chemotaxis and its membrane target for the metabolic burst

Affinity-purified IgA from the serum of an 8-year-old boy with a 5-year history of recurrent facial nodules, intermittent neutropenia and elevated immunoglobulin levels, inhibited the chemotaxis of polymorphonuclear neutrophils (PMN) from both patient and normal adults. Preincubation of normal PMN with IgA from the patient's serum (0.5 mg/ml) inhibited chemotaxis to C5a and to the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP) by 80%, while IgA or IgG from pooled human serum and IgG from the patient were without effect. Normal PMN chemotaxis was restored after IgA depletion of the patient's serum by affinity chromatography. The patient's IgA, but not IgA from pooled human serum, bound specifically to normal PMN by its antigen-binding sites and recognized a 62,000 MW membrane protein on normal neutrophils, which was distinct from the FMLP receptor, the C5a receptor, or the Fca receptor. Attachment of the patient's IgA to the 62,000 MW protein activated intracellular oxidative metabolism on a parity with phorbol myristate acetate (PMA) and resulted in a significant up-regulation of membrane receptors for FMLP. After the binding of patient (Pt) IgA, normal neutrophils were rendered significantly less responsive to subsequent stimulation with phorbol esters. These results characterize a novel mechanism of chemotactic inhibition by serum IgA and also identify a neutrophil membrane protein that is linked to intracellular oxidative metabolism.

Formyl peptide-induced chemotaxis of human polymorphonuclear leukocytes does not require either marked changes in cytosolic calcium or specific granule discharge. Role of formyl peptide receptor reexpression (or recycling)

We examined the role of intracellular and extracellular calcium on the ability of human polymorphonuclear leukocytes to migrate chemotactically and reexpress (or recycle) formyl peptide receptors when challenged with the synthetic chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (FMLP). Extracellular calcium was not required for either optimal chemotactic responses or receptor reexpression. Depletion and chelation of intracellular calcium resulted in significant diminution in the ability of polymorphonuclear leukocytes to release the specific granule constituents lactoferrin and vitamin B12-binding protein during the process of chemotaxis, but had no effect on the capability of these cells to respond chemotactically. Similarly, chelation of intracellular calcium did not affect the ability of these cells to reexpress a population of formyl peptide receptors. Inhibition of receptor reexpression, by a nonagglutinating derivative of wheat-germ agglutinin, was associated with inhibition of chemotactic responses to FMLP. Thus, it appears that large changes in cytosolic free calcium are not necessary for formyl peptide-induced polymorphonuclear leukocyte chemotaxis. In contrast, continuous reexpression (or recycling) of formyl peptide receptors is required for polymorphonuclear leukocyte chemotactic responses to FMLP, a process that appears to be independent from specific granule fusion with plasma membrane.

Inhibition of polymorphonuclear leucocyte functions in vivo by Yersinia enterocolitica lipopolysaccharide

A single intravenous injection of 5 micrograms of Yersinia enterocolitica lipopolysaccharide (LPS) inhibits rabbit polymorphonuclear leucocyte (PMN) chemotaxis, enzyme secretion, and respiratory burst activation in response to partially purified rabbit C5a and leucotriene B4 (LTB4). Respiratory burst activation is also inhibited in response to platelet activating factor (PAF). In contrast, all these responses to n-formyl-methionyl-leucyl-phenylalanine (FMLP) remain unaltered. This LPS does not modulate PMN activation in vitro or activate the respiratory burst. Thus Y enterocolitica LPS acts in vivo by inhibiting PMN responses to endogenous mediators of inflammation. This inhibition presumably impairs the elimination of pathogens and might, therefore, provide favourable conditions for induction by bacteria of further immunological consequences.

Defective phagocytosis, decreased tumour necrosis factor-alpha production, and lymphocyte hyporesponsiveness predispose patients with systemic lupus erythematosus to infections

Twenty-three patients with systemic lupus erythematosus (SLE) were studied in order to understand the mechanism of increased susceptibility to infection in SLE patients. We found that phagocytosis by polymorphonuclear leucocytes (PMN) was significantly defective in untreated (24.2 +/- 3.1%) and immunosuppressant-treated SLE patients (30.0 +/- 3.6%) compared with normals (47.9 +/- 0.6%), while the generation of superoxide anion radicals was normal. The defective phagocytosis in SLE could be increased by human recombinant tumour necrosis factor alpha (TNF-alpha). However, the percentages of phagocytosis in SLE before and after TNF-alpha stimulation were 56.6% and 60.7% of the normal values. This indicates that certain populations of PMN in SLE are not only defective as regards phagocytosis but also unresponsive to TNF-alpha stimulation. In an ELISA, TNF-alpha production by phorbol myristate acetate (PMA)-stimulated mononuclear cells from SLE patients was significantly decreased (181.4 +/- 22.7 pg/ml vs. 533.0 +/- 81.9 pg/ml, p = 0.002). In addition, the percentage of phytohaemagglutinin (PHA)-stimulated mononuclear cells in S phase in the cell cycle was deficient in patients with SLE (17.2 +/- 1.8% vs. 29.7 +/- 2.9%, p less than 0.001). These results lead us to propose that defective PMN in spontaneous and TNF-alpha-induced phagocytosis, decreased production of TNF-alpha, and lymphocyte hyporesponsiveness predispose patients with SLE to infections.

Identification of the C5a des Arg cochemotaxin. Homology with vitamin D-binding protein (group-specific component globulin)

The chemotactic activity of human C5a des Arg is enhanced significantly by an anionic polypeptide (cochemotaxin) in normal human serum and plasma. The cochemotaxin attaches to sialic acid residues within the oligosaccharide chain of native C5a des Arg to form a complex with potent chemotactic activity for human PMN. We investigated the nature of the cochemotaxin and found that vitamin D-binding protein is the putative cochemotaxin. Vitamin D-binding protein enhanced the chemotactic activity of native C5a des Arg, but had no effect on the chemotactic activity of either native C5a or FMLP. Sialic acid prevented both enhancement by vitamin D-binding protein of the chemotactic activity of native C5a des Arg and formation of C5a des Arg-vitamin D-binding protein complexes, detected by molecular sieve chromatography. Furthermore, vitamin D-binding protein and cochemotaxin exhibited identical molecular weights, isoelectric points, antigenic reactivity, and amino acid composition.

Myelokathexis associated with multiple congenital malformations: immunological study on phagocytic cells and lymphocytes

A 5-year-old boy was first seen at the age of 11 months when he presented with growth retardation, skeletal dysmorphisms and neutropenia. Since then he has remained leukopenic except when he has pulmonary infections with a marked leukocytosis. Despite his neutropenia, marked myeloid hyperplasia was evident on marrow smear examination; many cells showed abnormally hypersegmented nuclei, with unusual shape or pyknotic nuclei. Phagocytic cells showed impaired phagocytosis, candidacidal activity, metabolic burst and chemotaxis. Moreover, the patient's serum generated less chemotactic activity than normal serum. These data indicate a selectively complex defect of the neutrophil during differentiation associated with the presence of an inhibitor of chemotactic factors in the patient's serum.

HLA-B51 may serve as an immunogenetic marker for a subgroup of patients with Behçet's syndrome

Epidemiologic data, family history, clinical data, HLA typing, neutrophilic chemotaxis, and immunofluorescence of clinically normal non-sun-exposed skin were studied in 46 Israeli non-Ashkenazi Jewish and Arab patients with Behçet's syndrome. HLA-B51 was present in 71 percent of the patient group as compared with 13 percent of the control group (relative risk = 17.1). In four of 30 families in the B51-positive group, there was a close relative of the proband with Behçet's syndrome who was carrying the HLA-B51 antigen. Neutrophilic chemotaxis in this group was enhanced in 80 percent of the patients, and in most patients no deposition of immunoglobulin in the dermo-epidermal junction was observed, whereas C3 was present in papillary vessels. In the B51-negative group, the family history was negative for Behçet's syndrome, neutrophilic chemotaxis was enhanced in only two of eight patients, and in four of six patients, IgM deposition was detected in the dermo-epidermal junction. It is concluded that in Israeli non-Ashkenazi Jews and Arabs, there is a significant association between HLA-B51 and the risk of developing Behçet's syndrome. The B51-positive patient group has a family history of the disease, enhanced neutrophilic chemotaxis, and a lack of immunoglobulin deposition in the dermo-epidermal junction.

Identification of a protein in sera of normal humans that inhibits fibroblast chemotactic and random migration in vitro

Normal human serum contains a 230,000 Mr protein that inhibits fibroblast chemotactic and random migration. This serum inhibitor of fibroblast migration (SIFM) is a heat-stable, trypsin-sensitive protein with a pI of 4.8 that reversibly inhibits the random and chemotactic migration of fibroblasts in vitro. Although SIFM effectively inhibits the chemotaxis of fibroblasts to interstitial collagens, fibronectin, lymphocyte-derived chemotactic factor for fibroblasts, and serum-derived chemotactic factor, it does not alter the chemotactic migration of human peripheral blood neutrophils or monocytes, and does not act as a cytotoxin to human dermal fibroblasts. The SIFM appears to act through a cell-directed mechanism to alter the fibroblast's ability to migrate. Serum inhibitor of fibroblast migration may function in vivo to modulate fibroblast migration under physiologic and pathologic conditions.

Attachment of human C5a des Arg to its cochemotaxin is required for maximum expression of chemotactic activity

The chemotactic activity of human C5a des Arg is enhanced significantly by an anionic polypeptide (cochemotaxin) in normal human serum and plasma. We have found that the cochemotaxin attaches to the oligosaccharide chain of native C5a des Arg to form a complex with potent chemotactic activity for human polymorphonuclear leukocytes. Although capable of enhancing the chemotactic activity of native C5a des Arg, the cochemotaxin had no effect on the chemotactic activity of either deglycosylated C5a des Arg, native C5a, or N-formyl-methionyl-leucyl-phenylalanine. Of the known components of the oligosaccharide chain, only sialic acid prevented enhancement by the cochemotaxin of the chemotactic activity exhibited by native C5a des Arg. Sialic acid also prevented the formation of C5a des Arg-cochemotaxin complexes, detected by acid polyacrylamide gel electrophoresis, molecular sieve chromatography on polyacrylamide gels, and sucrose density gradient ultracentrifugation.

Endotoxin tolerance diminishes certain antiinflammatory effects of endotoxin

Endotoxin (bacterial lipopolysaccharide, LPS) is paradoxically both inflammatory and antiinflammatory. A single intravenous injection of 100 micrograms Escherichia coli LPS markedly inhibits the inflammatory changes associated with cutaneous reversed passive Arthus (RPA) reactions in New Zealand white rabbits. Polymorphonuclear (PMN) leukocytes from LPS-treated rabbits exhibit diminished responsiveness in vitro to complement (C5) -derived peptides. Repeated injections of LPS render animals "tolerant", that is, refractory to the toxic and inflammatory effects of LPS. We examined whether tolerance would enhance the ability of LPS to inhibit inflammation not attributable to LPS. Surprisingly, as compared with rabbits receiving a single dose of LPS, tolerant rabbits demonstrated greater inflammatory changes (i.e., PMN exudation, vascular permeability) associated with RPA reactions. PMNs from LPS-tolerant rabbits responded in vitro to C5-derived peptides significantly more than PMNs from rabbits that received a single dose of LPS. We speculate that some antiinflammatory effects of LPS require the toxic or inflammatory effects of LPS itself. These observations might relate to the limited efficacy of fever therapy and the variable effects of gram-negative sepsis on functions of human PMNs.

Transient absence of C5a-specific neutrophil function in inflammatory disorders of the skin

Chemotactic migration, production of superoxide anion (O2-), and the release of beta-glucuronidase from azurophilic granules were determined in polymorphonuclear leukocytes (PMN) from 135 patients with infectious (e.g., pyoderma, acne conglobata, erysipelas) as well as noninfectious (psoriasis) skin diseases. Purified C5a and the formylated tripeptide FMLP were used as stimuli. In addition, longitudinal profiles of PMN activities were performed at daily intervals in several patients. There was a complete absence of PMN responses (chemotaxis, O2--production, and enzyme release) specifically induced by C5a in 25 patients suffering from various inflammatory diseases of the skin. In these patients PMN responsiveness for the tripeptide FMLP was either normal or increased. The C5a-dependent defect of PMN was transient and correlated with disease activity. When normal PMN were incubated with sera from C5a-defective patients, no inherent stimulatory or inhibitory activities compared to control sera were seen. Pretreatment of normal PMN in vitro with various concentrations of C5a failed to completely deactivate PMN without affecting FMLP dependent functions. These observations demonstrate the presence of a functional defect in circulating PMN during acute cutaneous inflammation. The in vitro experiments suggest transient blocking of C5a-dependent PMN functions by a cell-bound factor which seems not to be C5a or C5adesarg.

Inhibition of human monocyte locomotion by products of axenically grown E. histolytica

The supernatant fluid of axenically grown E. histolytica inhibits chemotaxis, chemokinesis and random mobility of human mononuclear phagocytes (MP) as measured in Boyden chambers. Human polymorphonuclear phagocytes (PMN) locomotion is apparently unaffected. The factor was found in comparable amounts in the supernatant fluid of axenic cultures of four E. histolytica strains that differed in their human pathogenicity and virulence, as well as in two entamoebas non-pathogenic for man. This dialysable and thermolabile MP-locomotion inhibiting entamoeba product (EP) can be absorbed out by incubation with MP, but not with lymphocytes, while partial absorption was observed using PMN. The MP-locomotion inhibitory effect of this EP was cancelled by inhibiting protein synthesis in the MP by means of cycloheximide. In vivo, this EP caused a delay in MP migration in Rebuck skin windows. The molecular weight of this EP lies between 478 and 765 by gel-sieve chromatography. Our results suggest a direct effect upon the cytoskeletal and locomotive apparatus of the MP. This MP-locomotion inhibiting EP could contribute to the paucity of the inflammatory reaction observed in the advanced stages of invasive amoebiasis and consequently also to the lack of scar tissue formation upon healing of amoebic lesions.

Activation of the complement system in patients with porphyrias after irradiation in vivo

Irradiation of the forearms of two patients with erythropoietic protoporphyria and one patient with porphyria cutanea tarda resulted in an in vivo activation of the complement system, as assessed by diminution of the hemolytic titers of the third component of complement by 23-57%, and of the fifth component of complement (C5) by 19-47%. Such treatment also generated chemotactic activity for human polymorphonuclear cells; the chemotactic activity was stable at 56 degrees C and antigenically related to human C5. On Sephadex G-75 chromatography the chemotactic activity eluted with an apparent molecular weight of 15,000. These in vivo results extend our previous in vitro observation of photoactivation of complement in sera from patients with erythropoietic protoporphyria and porphyria cutanea tarda, and suggest that the complement system may participate in the pathogenesis of cutaneous phototoxicity in these patients.

Complement (C5)-derived chemotactic activity accounts for accumulation of polymorphonuclear leukocytes in cerebrospinal fluid of rabbits with pneumococcal meningitis

Experiments were performed to identify the chemoattractant for polymorphonuclear leukocytes that appears in the cerebrospinal fluid of rabbits with experimental pneumococcal meningitis. Meningitis was induced in anesthetized New Zealand white rabbits by injecting 10(4) cells of stationary-phase Streptococcus pneumoniae type III intracisternally. Before bacteria were injected, cerebrospinal fluid contained neither polymorphonuclear leukocytes nor chemotactic activity. Significant chemotactic activity for rabbit polymorphonuclear leukocytes was detected 12 h after inoculation with bacteria and was maximal after 18 to 20 h. Chemotactic activity appeared in cerebrospinal fluid while concentrations of pneumococci and total protein were increasing but before there was any accumulation of polymorphonuclear leukocytes. The chemotactic activity in cerebrospinal fluid was heat stable (56 degrees C for 30 min), eluted from Sephadex G-75 with a profile identical to that of the chemotactic activity in zymosan-activated rabbit serum, and was inhibited by treatment with antibodies to native human C5. In addition, preincubation of polymorphonuclear leukocytes with partially purified rabbit C5a selectively inhibited their subsequent chemotactic responses to cerebrospinal fluid. These data indicate that complement (C5)-derived chemotactic activity appears in cerebrospinal fluid during the course of experimental pneumococcal meningitis in rabbits and suggest that this activity accounts for the accumulation of polymorphonuclear leukocytes observed in this infection.

Production of chemotactic activity for polymorphonuclear leukocytes by cultured rat hepatocytes exposed to ethanol

Acute alcoholic hepatitis is characterized by infiltration of the liver parenchyma with polymorphonuclear leukocytes. As a possible explanation for this phenomenon, we have found that ethanol stimulates cultured rat hepatocytes to generate potent chemotactic activity. Hepatocytes (greater than 99% pure), isolated from the livers of Sprague-Dawley rats, responded to incubation with ethanol (2.0-10 mM) by releasing chemotactic activity for human polymorphonuclear leukocytes into culture supernatants in a time- and concentration-dependent fashion. Chemotactic activity was maximal after incubation of hepatocytes with 10 mM ethanol for 6 h. It was undetectable in the absence of ethanol and was reduced in the presence of either the alcohol dehydrogenase inhibitor, 4-methylpyrazole, or the acetaldehyde dehydrogenase inhibitor, cyanamide. Ethanol failed to stimulate generation of chemotactic activity by either rat dermal fibroblasts, hepatic sinusoidal endothelial cells, or Kupffer cells. The chemotactic activity generated by ethanol-treated rat hepatocytes was recovered from culture supernatants in the lipid phase after extraction with chloroform/methanol. Thin-layer chromatography and high performance liquid chromatography of chloroform/methanol extracts demonstrated that the chemotactic factor probably is a polar lipid. This chemotactic lipid may account, in part, for the leukocytic infiltration of the liver parenchyma that is observed during the course of acute alcoholic hepatitis.

C5a-inhibitor deficiency in peritoneal fluids from patients with familial Mediterranean fever

Normal peritoneal fluid contains an inhibitor of neutrophil chemotaxis that acts by antagonizing the complement-derived chemotactic anaphyllatoxin C5a. The inhibitor resembles a substance previously described in synovial fluids and is a protein with a molecular weight of approximately 40,000 as determined by gel filtration. In contrast, levels of inhibitory activity in peritoneal fluids from five patients with familial Mediterranean fever were decreased to less than 10 per cent of those found in normal subjects. Gel filtration of peritoneal and synovial fluids from these patients did not yield any fraction with inhibitory activity. We suggest that C5a-inhibitor deficiency in joint and peritoneal fluids from patients with familial Mediterranean fever may have a role in the pathogenesis of the inflammatory attacks characteristic of this disease.

Complement and endotoxin-induced lung injury in sheep

Intravenous infusions of endotoxin in sheep cause lung injury characterized by edema due to increased microvascular permeability. Similar increases in pulmonary microvascular permeability are seen in septic patients with the adult respiratory distress syndrome. Since endotoxin-induced lung injury may be mediated by interactions between products of complement activation and polymorphonuclear leukocytes, plasma and lung lymph from six unanesthetized sheep infused with Escherichia coli endotoxin (1.0 micrograms/kg over 30 min) were examined for complement-derived chemotactic activity. By 2-3 hr following infusion of endotoxin, all animals had the increased lung lymph fluid and protein flows characteristic of permeability edema. Preinfusion samples of plasma and lung lymph did not contain chemotactic activity for polymorphonuclear leukocytes. Following infusion of endotoxin, however, significant chemotactic activity was detected in plasma at 0.5-3.5 hr (P less than 0.05) and in lymph at 1.5-6.5 hr (P less than 0.025). The chemotactic activity was heat stable (56 degrees C for 30 min) but was abolished by treatment with antibodies to C5. These data indicate that infusions of endotoxin lead to the generation in plasma, and the appearance in lung lymph, of C5-derived peptides with chemotactic activity for polymorphonuclear leukocytes. C5-derived peptides may account for the pulmonary microvascular leukostasis and endothelial injury that lead to increased permeability edema after infusions of endotoxin.

Biologically active complement (C5)-derived peptides and their relevance to disease

In man and in most mammals, activation of the complement system via either the classical or the alternative pathway results in the generation of biologically active peptides. The most active peptides are C5a and C5a des Arg generated by cleavage of the alpha-chain of native C5. C5a is a potent anaphylatoxin and can induce human polymorphonuclear leukocytes to migrate in a directed fashion, to degranulate, to undergo a burst of oxidative metabolism and to aggregate. Upon generation C5a is converted in serum and plasma to C5a des Arg with loss of the noxious anaphylatoxin activity. C5a/C5a des Arg play important roles in host defenses against bacterial infections and possibly in the mediation of some pathologic lesions such as the leukocyte infiltration seen in the lungs during acute respiratory distress syndrome.

Antiinflammatory effects of endotoxin. Inhibition of rabbit polymorphonuclear leukocyte responses to complement (C5)-derived peptides in vivo and in vitro

Although capable of provoking a variety of inflammatory effects, endotoxin (bacterial lipopolysaccharide) paradoxically has been reported to be antiinflammatory. The authors have found that single intravenous injections of Escherichia coli endotoxin, 24 hours before challenge, inhibit almost completely the vascular permeability changes and exudation of polymorphonuclear leukocytes induced in rabbit skin by reversed passive Arthus reactions. Whereas intravenous injections of endotoxin also caused modest inhibition of the vascular permeability changes induced in rabbit skin by the synthetic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP), exudation of polymorphonuclear leukocytes was unaffected. Polymorphonuclear leukocytes from rabbits given single injected doses of endotoxin exhibited markedly diminished chemotactic and degranulation responses to complement (C5)-derived peptides in vitro. Responses of these cells to FMLP, however, were normal. These data suggest that selective suppression of polymorphonuclear leukocyte responses to C5-derived peptides accounts, in part, for the antiinflammatory effects of endotoxin.

Role of complement and polymorphonuclear cells in demethylchlortetracycline-induced phototoxicity in guinea pigs. Inhibition by decomplementation in vivo

In this study, demethylchlortetracycline was used as a prototype of exogenous phototoxic substances. In vitro, exposure of serum containing demethylchlortetracycline to ultraviolet-A irradiation resulted in the diminution of total complement hemolytic activity and C4, C2, C3, and C5 activities. In addition, chemotactic activity for human polymorphonuclear cells was generated, which was thermostable and antigenically related to human C5 but not human C3. In vivo, phototoxic lesions were induced in guinea pigs upon intradermal injections of demethylchlortetracycline solution, followed by ultraviolet-A irradiation. On a scale of 0-3+, the animals developed a maximal response of 2.5 at 20 h. This clinical response was associated with cellular infiltrate in the dermis, consisting of 29 +/- 2% of neutrophils at 24 h. The participation of the polymorphonuclear cells was evaluated in guinea pigs rendered neutropenic by treatment with cyclophosphamide. In these guinea pigs, demethylchlortetracycline and ultraviolet-A induced a maximal response of 0.75 +/- 0.5, which was associated histologically with 1.2 +/- 0.5% neutrophils in the dermis. The role of complement in this process was studied in guinea pigs congenitally deficient in C4, and in guinea pigs decomplemented by treatment with cobra venom factor. In contrast to normal guinea pigs, C4-deficient animals exhibited a maximal reaction of 0.83 +/- 0.16 at 6 h, which subsided within 24 h. Cobra venom factor-treated guinea pigs developed a maximal response of 0.5 at 0.5 and at 6 h. These clinical changes were associated with the development of an increased vascular permeability, as demonstrated by studies using guinea pigs injected intravenously with Evans blue solution. In animals with a normal complement system, there was intense localized bluing at the sites of phototoxic lesion. In contrast, only minimal bluing was observed in decomplemented guinea pigs. These data indicate that a normal number of polymorphonuclear cells and an intact complement system are required for the full development of demethylchlortetracycline-induced phototoxic lesions.

Complement-activating immune deposits in systemic lupus erythematosus skin

Immune deposits at the cutaneous basement membrane zone are a characteristic feature of systemic lupus erythematosus. Previous studies using immunofluorescent methods to detect complement components have provided evidence that some deposits contain immune complexes capable of activating complement. However, this important biologic property of complexes has not been detected or measured using functional assays, and it has not been determined whether immune deposits can activate complement at the basement membrane zone. In this study immune deposits in biopsies of lupus skin have been examined using direct immunofluorescence for the third component of complement (C3) to detect complement deposited in vivo. In addition, the deposits have been studied using the leukocyte attachment assay and indirect C3 binding immunofluorescence to detect and measure complement activation at the basement membrane zone in vitro. The results show that complement activation occurs at the basement membrane in some but not all lupus skin containing immunoglobulin deposits, that deposits differ quantitatively in their ability to activate complement, and that direct C3 immunofluorescence is a relatively insensitive method for detecting complement-activating complexes. The results provide functional evidence suggesting that immune deposits in some lupus skin are complement-activating complexes and potentially capable of activating complement at the basement membrane in vivo. Furthermore, the results suggest functional assays for evaluating complement-activating complexes may be valuable supplements to immunofluorescence in exploring the relationship between immune deposits and systemic and cutaneous disease.

Influence of hemodialysis on plasma chemotactic activity and the chemotactic responsiveness of polymorphonuclear neutrophils

Thirty patients with chronic renal failure on maintenance hemodialysis (HD) were studied. Plasma chemotactic activity was estimated using the "under agarose" chemotaxis assay during the first 2 h of HD. It was found that in the fifth minute of HD, patients' plasma became chemotactic, reaching the maximum activity at the tenth minute. The chemotactic activity appearance correlated significantly with the decline in the number of the peripheral neutrophils. Patients' neutrophils, after a single passage through the cellophane coil of the dialyzer, revealed significant impairment of directed migration toward both complementary and bacterial chemoattractants. Moreover, the chemotactic properties of neutrophils obtained from dialyzed patients before HD were significantly lower than had been estimated in 15 nondialyzed patients with chronic renal failure. The results confirm HD-induced complement activation and might explain the mechanisms of the increased susceptibility of dialyzed patients to bacterial infections.

Polymorphonuclear leukocytes: dedicated professional phagocytes

Polymorphonuclear leukocytes are termed professional phagocytes because they are specially equipped to seek and destroy invading microorganisms. Polymorphonuclear leukocytes are formed in the bone marrow and released into the circulation, where they are transported to the tissues. At sites of tissue invasion by microorganisms, humoral factors are released that induce these cells to leave the bloodstream and enter the tissues. Chemotactic substances guide polymorphonuclear leukocytes to the infecting organisms. Antibody and complement can function as opsonins and enhance the ability of polymorphonuclear leukocytes to engulf microbes. Ingested organisms are killed by oxidative or nonoxidative systems. Defects in the various aspects of polymorphonuclear leukocyte function may be found in patients with recurrent, severe, or unusual infections. Evaluation of selected patients with recurrent infections should include tests of polymorphonuclear leukocyte function.

Radioimmunoelectrophoresis, a sensitive method for detecting cleavage of the fifth component of human complement (C5)

A method has been developed for detecting cleavage of human C5 in serum and whole blood as a consequence of complement activation. Standard, single-dimension immunoelectrophoresis was performed using as antibody a radioiodinated IgG fraction prepared from a commercially available antiserum to human C5. Autoradiographs developed after radioimmunoelectrophoresis of either normal human serum or functionally pure human C5 revealed only one precipitin band. In contrast, when either zymosan-treated serum or trypsin-treated human C5 were examined with this technique, two additional precipitin bands were detected. One migrated more anodally than native C5 while the other remained at the origin (cathode). Radioimmunoelectrophoresis was significantly more sensitive as an indicator of complement activation in human serum than either measurements of total hemolytic complement or a standard assay for complement (C5)-derived chemotactic activity.

Increased endothelial cell adherence, aggregation, and superoxide generation by neutrophils incubated in systemic lupus erythematosus and Felty's syndrome sera

The ability of sera from patients with systemic lupus erythematosus (SLE) and Felty's syndrome to induce increased adhesiveness of normal human neutrophils (PMN) was investigated. PMN from normal healthy donors were incubated in sera from 19 patients with active SLE, 12 with inactive SLE, 20 with Felty's, 24 with rheumatoid arthritis, and 34 normal persons. After incubation, the degree of adherence of the PMN to human endothelial cells in culture, their aggregation, and superoxide (O2-) generation were determined. Sera from patients with both active SLE and Felty's syndrome induced significantly increased PMN adherence to endothelial cells and PMN aggregation in vitro, compared with normal sera. This increased adherence to endothelial cells was maintained after heat treatment (56 degrees C for 30 minutes) of the sera. In O2- generation experiments, sera from patients with active SLE induced significantly increased O2- release from normal PMN using both fresh and heat-treated sera. Sera from Felty's patients demonstrated the same effect with heat-treated sera but not ith fresh sera. When sera from patients with active SLE and Felty's syndrome were used, all three parameters correlated significantly with each other in individual patients. In contrast, sera from the 12 patients with inactive SLE and 24 rheumatoid arthritis patients without Felty's failed to induce significant differences in the three parameters studied when compared with 34 normal controls. Fractionation of 3 SLE sera and 1 Felty's serum on Sephadex G-200 demonstrated that the adherence enhancing factor was present in both IgG and IgG-excluded fractions. The observed increased adhesiveness of PMN induced by SLE and Felty's sera may, at least in part, contribute to the neutropenia which is common in these diseases. Increased O2- release associated with PMN adherence may contribute to endothelial cell damage and vascular injury, which is also a common manifestation of these diseases.

The effects of retinoids on neutrophil functions in vitro

Vitamin A (retinol) and its analogues (retinoids) are clinically effective in cystic acne and psoriasis, diseases in which neutrophils may constitute major components of inflammatory cell infiltrates. We found that the earliest histopathologic alteration in psoriasis is the disappearance of neutrophils at 2 to 4 weeks after the initiation of therapy with etretinate. Since retinoids may exert anti-inflammatory effects by virtue of an action upon neutrophils, we studied the effects of the following retinoids on discrete neutrophil functions in vitro: retinol, retinyl acetate, retinal, tretinoin, isotretinoin, etretinate, and Ro 10-1670. Although they had no significant effects upon aggregation, chemokinesis, or chemotaxis, all of the retinoids, with the exception of etretinate and Ro 10-1670, profoundly inhibited superoxide anion production and lysosomal enzyme release. Tretinoin and isotretinoin were the most effective inhibitors. We propose that these drugs exert their pharmacologic effects (resolution of inflammatory lesions) by inhibiting the release of mediators of inflammation and by preventing the accumulation of neutrophils in acne lesions when applied topically or systemically, respectively.

Neutrophil function in systemic lupus erythematosus and other collagen diseases

Using a whole blood technique we assessed neutrophil migration, phagocytosis, and killing in a group of 20 patients with systemic lupus erythematosus (SLE) and in 8 patients with other connective tissue disorders. In the untreated cases of SLE neutrophil migration was significantly depressed, but it was usually normal in the treated group. This may be attributable either to an intrinsic neutrophil abnormality or to a humoral factor. Although isolated abnormalities of phagocytosis and killing were observed in SLE, these functions were normal when the patients were considered as a group. The treated patients with other collagen diseases showed enhanced migration in both autologous and control plasma, normal phagocytosis, and enhanced killing in autologous plasma only. The small group of untreated, non-SLE patients showed some depression of all 3 functions. There was no correlation between neutrophil function and clinical activity of disease. In the SLE patients there was no correlation between neutrophil function and circulating immune complexes.

Effect of high-dose methylprednisolone infusion on polymorphonuclear leukocyte function in patients with systemic lupus erythematosus

We have studied the effect of high-dose (1 gm) methylprednisolone infusion on polymorphonuclear leukocyte (PMN) function in 11 patients with active systemic lupus erythematosus (SLE). The only alteration of polymorphonuclear leukocyte function produced consistently by methylprednisolone was decreased adherence to plastic surfaces when tested 2 hours after infusion. This steroid-induced abnormality, however, was transient. Cells obtained from patients 24 hours after a single dose of drug exhibited normal adhesiveness. These results indicate that single, large doses of methylprednisolone do not produce long-lasting abnormalities of PMN function in patients with lupus.

Complement-derived chemotactic activity is generated in human serum containing uroporphyrin after irradiation with 405 nm light

Patients with porphyrias have varying degrees of photosensitivity, associated with elevated levels of porphyrins in plasma, erythrocyte, urine and/or feces. To investigate the role of complement in the pathogenesis of cutaneous lesions, varying amounts of uroporphyrin were added to normal human serum (0.1-10 microgram/ml), and the mixtures were then exposed to 405 nm irradiation. Such treatments result in the diminution of total hemolytic complement activity and hemolytic titers of C1, C4, C2, C3, and C5; furthermore, cleavage products of C3 and C5 were detected. Chemotactic activity for human polymorphonuclear leukocytes was generated that was inhibitable by incubation with anti-C5, but not with anti-C3 antisera. No chemotactic activity was generated in Mg++-EGTA treated serum nor in C4-deficient guinea pig serum. These data indicate that irradiation with 405 nm light of normal human serum containing uroporphyrin results in activation of the complement system via the classical pathway, and the generation of complement (C5)-derived chemotactic activity for human polymorphonuclear leukocytes.

An immunoglobulin (IgG) inhibitor of polymorphonuclear leukocyte motility in a patient with recurrent infection

We isolated from the serum of a patient with recurrent skin infections an IgG immunoglobulin that irreversibly inhibits the random motility and chemotactic responsiveness of polymorphonuclear leukocytes. Although the patient's leukocytes behaved like normal cells with respect to adherence, phagocytosis, degranulation, and generation of the superoxide anion, they did not migrate normally toward standard chemotactic stimuli. Normal human polymorphonuclear leukocytes behaved similarly after incubation with the patient's serum. Inhibition of motility was not associated with cyutotoxicity. Inhibitory activity could be removed completely from the patient's serum by treatment with either agarose-bound anti-human IgG or Sepharose-bound staphylococcal protein A. Exposure of normal polymorphonuclear leukocytes to as little as 1.25 microgram per milliliter (0.00125 g per liter) of the patient's purified IgG caused significant inhibition of random motility and chemotactic responsiveness (P < 0.01). Thus, IgG immunoglobulins can inhibit leukocyte motility specifically and irreversibly, and thereby adversely affect host defenses against invading microorganisms.

Evidence of complement catabolism in experimental acute pancreatitis

Serum specimens from guinea pigs with experimentally induced acute pancreatitis were examined for evidence of protease-antiprotease imbalance and complement catabolism. Pancreatitis was induced in 22 male Hartley guinea pigs by the injection of sodium taurocholate into the pancreatic parenchyma. Only a laparotomy was performed in 6 control animals. In 10 experimental animals that survived for less than 24 hours, there was a significant, early reduction of serum trypsin inhibitory capacity (a measure of antiprotease activity). Levels of total hemolytic complement as well as titers of hemolytic C3 and C4 fell significantly in all experimental animals during the first 24 hours. Factor B activity, however, did not change. Only serum from experimental animals contained chemotactic activity for human polymorphonuclear leukocytes. These findngs indicate that circulating complement components are cleaved during the course of experimental acute pancreatitis. As a consequence, complement-derived peptides are generated that may mediate local and systemic tissue injury.

Infection in patients with systemic lupus erythematosus. Association with a serum inhibitor of complement-derived chemotactic activity

We have found subnormal amounts of chemotactic activity in zymosan-treated sera from 13 of 29 patients with systemic lupus erythematosus (SLE). As an explanation for this abnormality, the presence of a uniquely specific, heat-stable inhibitor of complement (C5)-derived chemotactic activity has been documented in sera from 11 of these patients. Sera from 2 other patients contained elevated levels of nonspecific, heat-labile chemotactic factor inactivator (CFI) activity. The serum from 1 patient contained the heat-stable inhibitor as well as elevated levels of CFI. Patients with SLE whose sera contained the heat-stable inhibitor had more active disease clinically, but otherwise they were indistinguishable from patients without the inhibitor. When patients with the heat-stable inhibitor improved clinically, this usually was accompanied by a decrease in serum inhibitory activity. Only one episode of bacterial infection was observed among 16 patients with SLE whose sera yielded normal amounts of chemotactic activity after treatment with zymosan. In contrast, 7 of 11 patients with SLE whose sera contained the heat-stable inhibitor suffered serious bacterial infections. The presence of this heat-stable inhibitor in sera from some patients with SLE may contribute, in part, to their increased susceptibility to infection.