The third component of complement protects against Escherichia coli endotoxin-induced shock and multiple organ failure.

We investigated whether the third component of complement (C3) is involved in the pathophysiology of endotoxic shock, and if it is involved, whether it plays a protective role or whether it mediates shock and multiple organ failure. In a prospective, controlled investigation, six Brittany spaniels that were homozygous for a genetically determined deficiency of C3 (C3 deficient, < 0.003% of normal serum C3 levels) and six heterozygous littermates (controls, approximately 50% of mean normal serum C3 level) were given 2 mg/kg of reconstituted Escherichia coli 026:B6 acetone powder as a source of endotoxin, intravenously. All animals were given similar fluid and prophylactic antibiotic therapy, and had serial hemodynamic variables obtained. After E. coli endotoxin infusion, C3-deficient animals had higher peak levels of endotoxin and less of a rise in temperature than controls (P < 0.05). During the first 4 h after E. coli endotoxin infusion, C3-deficient animals had significantly greater decreases in mean central venous pressure and mean pulmonary artery pressure than controls (P < 0.02). During the first 48 h after E. coli endotoxin infusion, C3-deficient animals had significantly greater decreases in mean arterial pH, left ventricular ejection fraction, and mean pulmonary capillary wedge pressure, and greater increases in mean arterial lactate, arterial-alveolar O2 gradient, and transaminases (aspartate aminotransferase and alanine aminotransferase) than controls, (all P < 0.05). After E. coli endotoxin infusion, C3-deficient animals compared to controls had significantly less of a decrease in mean C5 levels (P < 0.01), but similar (P = NS) increases in circulating tumor necrosis factor levels, bronchoalveolar lavage neutrophils, and protein, and similar (P = NS) decreases in blood leukocytes and platelets. Two of six C3-deficient animals and two of six controls died. In summary, after intravenous infusion of E. coli endotoxin, canines with C3 deficiency have decreased endotoxin clearance and worse E. coli endotoxin-induced shock and organ damage. Thus, the third component of the complement system plays a beneficial role in the host defense against E. coli endotoxic shock.

Genetically determined deficiency of the third component of complement in the dog.

A genetically determined deficiency of the third component of complement (C3) has been identified in a colony of Brittany spaniels. Immunochemical methods show no detectable C3 in the serum of the affected dogs, and there is no evidence of an inhibitor of C3 in the serum. The C3 deficiency appears to be transmitted as an autosomal recessive trait.

Bacterial lipoteichoic acid sensitizes host cells for destruction by autologous complement.

Lipoteichoic acids (LTA) released by gram-positive bacteria can spontaneously bind to mammalian cell surfaces. In the present study, erythrocytes (E) sensitized with pneumococcal LTA (LTA-E) were used as a model system to determine if LTA could render host cells susceptible to damage by autologous complement. Complement (C)-mediated lysis of LTA-E from normal rats and normal humans occurred when these cells were incubated in their respective autologous sera in vitro. In addition, when LTA-E from a C2-deficient human and from C4-deficient guinea pigs were incubated in their autologous sera, there was significant lysis in vitro, demonstrating a role for the alternative pathway. The in vivo survival of 51Cr-labeled autologous LTA-E was also studied. Only 2.9% of autologous LTA-E remained in the circulation of normal rats after 90 min. In contrast, 31.2% of autologous LTA-E remained in the circulation of rats depleted of C3. Intravascular hemolysis accounted for the clearance of LTA-E in the normal rats, whereas liver sequestration was responsible for clearance in the C3-depleted rats. These results demonstrate that LTA can render the host's cells susceptible to damage by its own complement system, establishing this as a possible mechanism of tissue damage in natural bacterial infections.

Oral administration of human serum immunoglobulin in immunodeficient patients with viral gastroenteritis. A pharmacokinetic and functional analysis.

We examined the pharmacokinetics and immunological activity of human serum immunoglobulins (HSG) possessing anti-rota-virus activity which were orally administered to three children with primary immunodeficiency syndromes and prolonged gastrointestinal excretion of rotavirus. Detailed analysis of the excretion of immunoglobulins labeled with biotin or I125 revealed that approximately 50% of the recovered radioactivity was excreted in the stools over a 3-d period. Approximately half of the excreted radioactivity recovered in the stool was in a macromolecular form with immunological activity. The remainder of the recovered radioactivity was excreted in the urine as low molecular weight fragments or free iodide. In addition, immunological and chromatographic analyses revealed that the oral administration of HSG resulted in the generation of rotavirus-specific immune complexes in the gastrointestinal tract with a subsequent decrease in the presence of uncomplexed rotavirus antigen. These studies indicate that orally administered HSG can survive passage in the gastrointestinal tract in an immunologically active form, and that the oral administration of immunoglobulins with specific reactivities has potential for the prevention or treatment of gastrointestinal infections.

A unique recombination event resulting in a C4A*Q0,C4B*Q0 double null haplotype.

The fourth component of complement (C4) is encoded by two closely linked genes (C4A and C4B) within the MHC. Null alleles at either locus (C4AQ0 or C4BQ0) are relatively common, occurring at the C4A locus in approximately 10% of normal individuals and at the C4B locus in approximately 16% of normal individuals. However, the presence of the double null haplotype (C4A*Q0,B*Q0) on the same chromosome is extremely rare. We recently studied a 7-yr-old patient with recurrent sinopulmonary infections in whom we documented the mechanism by which the C4A*Q0,B*Q0 double null haplotype arose. Evaluation revealed significantly reduced levels of both C4 antigen and C4 hemolytic activity. Analysis of extended haplotypes in the family was performed using MHC typing and genomic DNA analysis. The patient was found to have a C4A*3,B*Q0 haplotype and a C4A*Q0,B*Q0 haplotype. The C4A*3,B*Q0 haplotype was contributed by the father. The mother possessed a C4A*Q0,B*1 haplotype and a C4A*3,B*1 haplotype. The first maternal haplotype was involved in a recombination event within the C4B locus on her other chromosome and resulted in a new C4B*Q0 null allele and the patient's C4A*Q0,B*Q0 haplotype. Segregation analysis mapped the recombination to a region 3' to the unique 6.4-kb TaqI restriction fragment of the maternal C4B locus. This is the first demonstration of a recombination event producing a C4 double null haplotype.

Host defense molecule polymorphisms influence the risk for immune-mediated complications in chronic granulomatous disease.

Chronic granulomatous disease (CGD) is an inherited disorder of phagocyte function in which defective superoxide production results in deficient microbicidal activity. CGD patients suffer from recurrent, life-threatening infections, and nearly half develop chronic gastrointestinal (GI) complications (colitis, gastric outlet obstruction, or perirectal abscess) and/or autoimmune/rheumatologic disorders (AIDs). To identify genetic modifiers of disease severity, we studied a cohort of 129 CGD patients, in whom seven candidate genes (myeloperoxidase [MPO], mannose binding lectin [MBL], Fcgamma receptors IIa, IIIa, IIIb, TNF-alpha, and IL-1 receptor antagonist), each containing a physiologically relevant polymorphism predicted to influence the host inflammatory response, were selected for analysis. Genotypes of MPO (P = 0.003) and FcgammaRIIIb (P = 0.007) were strongly associated with an increased risk for GI complications, while an FcgammaRIIa (P = 0.05) genotype was suggestive for an association. Patients with all three associated genotypes had the highest risk for GI complications (P < 0.0001). The risk of AIDs was strongly associated with variant alleles of MBL (P = 0.01) and weakly associated with an FcgammaRIIa genotype (P = 0.04). Patients with variant forms of both MBL and FcgammaRIIa had the highest risk of developing an AID (P = 0.003).

X-linked agammaglobulinemia: an analysis of 96 patients.

We have defined the clinical presentation and course of X-linked agammaglobulinemia (X-LA) by means of a multi-center retrospective survey of 96 patients. Infections were the most common presenting feature of patients with X-LA. The most frequent infections involved the upper respiratory tract (75%), lower respiratory tract (65%), gastrointestinal tract (35%), skin (28%), and central nervous system (16%). Clinical clues to the diagnosis of X-LA were the chronic or recurrent nature of infections, a family history of immunodeficiency, and infections at more than one anatomic location. Infections remained a significant problem after the diagnosis of X-LA was made and gamma-globulin prophylaxis had been instituted. One or more chronic infectious diseases occurred in 71% of patients. The respiratory tract was the most common site of disease, and the gastrointestinal tract was relatively spared. Patients died at a mean age of 17 years. The two major causes of death were chronic pulmonary disease with resultant cardiac failure, and disseminated viral infections which characteristically caused a dermatomyositis-like syndrome, hepatitis, pneumonitis, and meningoencephalitis.

Clinical expression of systemic lupus erythematosus in patients with C4A deficiency.

We studied 121 patients with systemic lupus erythematosus (SLE), of whom 119 were complement typed. Both black and white patients with SLE were more likely than racially matched controls to have a C4A null allotype. Patients with homozygous C4A deficiency had less proteinuria than other patients (p = 0.02) and both homozygous and heterozygous C4A-deficient patients (p = 0.05) had fewer seizures than other patients. Anti-dsDNA, anti-Sm, anti-Ro, and anticardiolipin antibodies were less common in patients with homozygous C4A deficiency, with heterozygous C4A-deficient patients intermediate in frequency between homozygous C4A-deficient and normal patients with SLE. Both homozygous and heterozygous C4A-deficient patients (p < 0.005) had higher C3 levels than other patients, and heterozygous C4A-deficient patients had higher, not lower, C4 levels (p < 0.002), compared with non-C4A-deficient patients. C4A gene deletion was found in 23.4% of patients. C4A gene deletion was associated with subacute cutaneous lupus erythematosus (p = 0.04) and Sjögren syndrome (p = 0.02) in patients with SLE. Both anti-dsDNA (p = 0.04) and anticardiolipin (p = 0.04) were found less frequently in patients with C4A gene deletion. Patients with C4A gene deletion had lower C4 levels than patients with C4A deficiency from other mechanisms. We conclude that the presence of 1 or 2 C4A null allotypes and the presence of a C4A gene deletion identify subgroups of patients with SLE that differ in clinical, laboratory, and autoantibody characteristics from other patients with SLE.

Oligo-/monoclonal gammopathy and hypergammaglobulinemia in ataxia-telangiectasia. A study of 90 patients.

We investigated the presence of hypergammaglobulinemia and oligo-/monoclonal gammopathy in 90 patients (from 80 families) with ataxia-telangiectasia ranging in age from 2 to 29 years. Of the 90 patients, 38.8% displayed hypergammaglobulinemia. An isolated increase in IgM was the most common finding (23.3%) followed by a simultaneous increase in IgM and IgG (8.8%), an isolated increase in IgA (3.3%), an elevated level of IgG (2.2%) and a concomitant increase in IgM and IgA (1.1%), respectively. Seven of the patients (8.1%) had oligo-/monoclonal gammopathy. The gammopathies included all major immunoglobulin isotypes. Chemotherapeutic intervention in 2 cases precipitated the emergence of new clones within a matter of weeks. Further investigation of oligo-/monoclonal gammopathies in these patients may lead to a clearer understanding of the clinical course and provide further insight into the underlying mechanisms of B-cell abnormalities in ataxia-telangiectasia.

Familial systemic lupus erythematosus: immunogenetic studies in eight families.

Familial SLE provides a unique opportunity to study the relationships of previously associated genetic factors (HLA and complement component deficiencies) to the occurrence of SLE, other immune disorders, and autoantibodies in families. Thus, eight families containing two or more affected members with SLE (n = 22) and their relatives (n = 40) were examined for HLA genotypes, complement components and autoantibodies. Among the 40 non-SLE relatives, 7 (18%) had other immune diseases, including thyroid disease in 2, rheumatoid arthritis in 2, ITP in 2, and Henoch-Schönlein purpura in one. This compared to 4 of the 22 SLE patients (also 18%) of whom 3 had thyroid disease and one PSS. Eleven non-SLE relatives (28%) had ANA, which was in high-titer in 5 (13%). Eleven (28%) had antibodies to ssDNA, and one had a BFP. Only the SLE patients had antidsDNA, Ro(SSA), Sm or nRNP. A heterozygous C2 deficiency (C2D) was found in only one of the seven kindreds studied, and followed an A25, B18 DR7 haplotype. Heterozygous C2D, however, was inherited by only one of three family members with SLE. HLA-DR2 occurred in 36% and DR3 in 36% of SLE patients, which was not significantly different from either non-SLE family members or unrelated local controls. Sib pair analysis of seven sets presented here and seven from two published reports, demonstrated only random distribution with SLE. Similarly, other immune disorders and autoantibodies followed no consistent HLA haplotypes or DR specificities. Interestingly, DR2 and/or DR3 were found in five of the six patients (83%) having anti-ro(SSA) antibodies (p = NS). These data strongly suggest that genetic factors (other than HLA and complement component deficiencies) and/or environmental factors are necessary for the expression of SLE and other immune abnormalities in lupus families.

Sarcoidosis and common variable immunodeficiency. Report of 8 cases and review of the literature.

The true incidence of sarcoidosis in common variable immunodeficiency (CVID) is unknown. We report here 8 cases of sarcoidosis among 80 patients with CVID followed in our clinics, along with 22 well-documented cases reported in the literature. Sarcoidosis, therefore, represents an important entity to consider among patients with CVID who exhibit clinical, radiographic, laboratory, and biopsy findings compatible with sarcoidosis. Conversely, the diagnosis of CVID should be considered in patients with sarcoidosis who do not exhibit the characteristic hypergammaglobulinemia and who have a history of recurrent infections. Although many features of sarcoidosis are similar in patients with CVID to those in patients with sarcoidosis alone, there are many important differences. Patients with CVID in whom sarcoidosis develops present with hypogammaglobulinemia rather than hypergammaglobulinemia and have a higher prevalence of recurrent infections, thrombocytopenia, and splenic involvement. Steroids, in most cases, appeared helpful in reducing adenopathy and splenomegaly, improving uveitis, lowering serum alkaline phosphatase, and reversing hematologic abnormalities. The underlying pathophysiology responsible for the association of these 2 disorders in the same patient remains obscure. However, as more patients are identified, it may be possible to gain a better understanding of the immunologic defect responsible for the dual presentation of these 2 relatively uncommon diseases.

Chronic granulomatous disease. Report on a national registry of 368 patients.

A registry of United States residents with chronic granulomatous disease (CGD) was established in 1993 in order to estimate the minimum incidence of this uncommon primary immunodeficiency disease and characterize its epidemiologic and clinical features. To date, 368 patients have been registered; 259 have the X-linked recessive form of CGD, 81 have 1 of the autosomal recessive forms, and in 28 the mode of inheritance is unknown. The minimum estimate of birth rate is between 1/200,000 and 1/250,000 live births for the period 1980-1989. Pneumonia was the most prevalent infection (79% of patients; Aspergillus most prevalent cause), followed by suppurative adenitis (53% of patients; Staphylococcus most prevalent cause), subcutaneous abscess (42% of patients; Staphylococcus most prevalent cause), liver abscess (27% of patients; Staphylococcus most prevalent cause), osteomyelitis (25% of patients; Serratia most prevalent cause), and sepsis (18% of patients; Salmonella most prevalent cause). Fifteen percent of patients had gastric outlet obstruction, 10% urinary tract obstruction, and 17% colitis/enteritis. Ten percent of X-linked recessive kindreds and 3% of autosomal recessive kindreds had family members with lupus. Eighteen percent of patients either were deceased when registered or died after being registered. The most common causes of death were pneumonia and/or sepsis due to Aspergillus (23 patients) or Burkholderia cepacia (12 patients). Patients with the X-linked recessive form of the disease appear to have a more serious clinical phenotype than patients with the autosomal recessive forms of the disease, based on the fact that they are diagnosed significantly earlier (mean, 3.01 years of age versus 7.81 years of age, respectively), have a significantly higher prevalence of perirectal abscess (17% versus 7%), suppurative adenitis (59% versus 32%), bacteremia/fungemia (21% versus 10%), gastric obstruction (19% versus 5%), and urinary tract obstruction (11% versus 3%), and a higher mortality (21.2% versus 8.6%).

Discriminant quantitation of posttransplant hepatic reticuloendothelial function. The impact of ischemic preservation.

This study focuses upon two discrete components of posttransplant hepatic reticuloendothelial system (RES) function-phagocytosis and killing of bacteria-under various conditions of ischemic preservation. We had previously reported that, following intravenous injection of rats with 51Cr and 125I double-labeled Escherichia coli, hepatic 51Cr levels can be used to reliably quantify hepatic phagocytic clearance of the bacteria from the blood (HPC), while the subsequent release of 125I from the liver accurately parallels hepatic bacterial killing. Here, Wistar rats were transplanted with syngeneic livers perfused with either normal saline (NS) or University of Wisconsin solution (UW) and stored at 4 degrees C for 1, 2, or 3 hr prior to implantation. Control rats underwent laparotomy and hepatic artery ligation. Using the double-labeled E coli assay, HPC was decreased in all transplanted animals when compared with controls, reaching a nadir on the third postoperative day (P < 0.05). In rats transplanted with livers preserved in NS, the fraction of phagocytosed organisms that were subsequently killed (hepatic killing efficiency=HKE) was increased to 142%, 129%, or 112% of normal following 1, 2, or 3 hr of cold ischemia, respectively; P < 0.05). Conversely, preservation of donor allografts in UW was associated with marked depression of HKE. Moreover, rats receiving NS- or UW-preserved livers tolerated an intravenous challenge with Streptococcus pneumoniae poorly (50% mortality) compared with hepatic artery ligated controls (12% mortality) at 7 days. Ischemic preservation of rat livers in NS resulted in a dose (of ischemia)-dependent reduction of hepatic phagocytosis coupled with a potentiation of HKE. Preservation in UW, however, produced a striking suppression of both components of hepatic RES function. Following a septic challenge survival was reduced in both groups of transplanted rats.

Consequences of the delayed diagnosis of ataxia-telangiectasia.

OBJECTIVES: Ataxia-telangiectasia (AT) is a rare, autosomal recessive neurodegenerative disorder in which the diagnosis is obvious when ataxia and telangiectasia are both present. However, the diagnosis can be made upon the onset of ataxia and before the appearance of telangiectasia if confirmed by laboratory tests. Early diagnosis is important for genetic counseling, appropriate care, and avoidance of unnecessary tests. The purpose of this study is to identify factors responsible for delays in the diagnosis of AT. DESIGN: The records of all patients seen at the Ataxia-Telangiectasia Clinical Center from July 1, 1995 to April 1, 1997 were reviewed to determine age of onset of gait abnormality, recognition of telangiectasia, and diagnosis. RESULTS: In 48 patients with AT, who were the index cases in their respective families, the median age of diagnosis (78 months) occurred after the onset of gait abnormalities (15 months) and closely corresponded to the development of telangiectasia (72 months). In the majority of cases (34/48), telangiectasia appeared before the diagnosis was established. The most common misdiagnosis was cerebral palsy (29/48 cases). Twenty-one children (4 with AT) were born after the start of symptoms in the index case, but before the establishment of a diagnosis. CONCLUSIONS: The term AT, although a concise and memorable label for the disorder, is also a barrier to early diagnosis. We recommend the use of routine serum alpha-fetoprotein testing for all children with persistent ataxia.

Complement-like activity in the sea star, Asterias forbesi.

The coelomic fluid (CF) of Asterias forbesi was examined for the presence of complement-like activity. Cell-free CF contains hemolytic activity for unsensitized rabbit erythrocytes (E) but not unsensitized or antibody-coated sheep E. Target E sensitivity is not dependent upon phylogenetic proximity of erythrocyte species to Asterias. The activity is optimally assayed at 25 degrees C, has a sigmoidal dose-response curve, and is heat-sensitive (56 degrees C). The activity is divalent cation dependent, although Ca++ and Mg++ are not required. Nonlytic CF does not contain an inhibitor; rather, combining nonlytic and lytic CFs results in an increase in hemolysis. Activity can be consumed by treatment with zymosan, pronase, trypsin, and PMSF. Enzymatic desialidation converts sheep E into activators of the hemolytic pathway. No phospholipase activity is present in CF. Biological function is demonstrated by bactericidal activity against Vibrio tubiashii by lytic CF. These results suggest that a primitive complement system is operating in Asterias.

Genetic analysis of an inherited deficiency of the third component of complement in Brittany spaniel dogs.

Genetically determined C3 deficiency in Brittany spaniel dogs shares a number of biochemical and clinical characteristics with the human disorder. In humans, the gene for C3 deficiency is a null gene that is allelic to the structural gene for C3 and is not linked to the major histocompatibility locus. The current study used allotype analysis of canine C3 in order to demonstrate that the gene for C3 deficiency in these dogs is also a null gene allelic to the structural gene for C3. In addition, preliminary pedigree analysis suggests that the gene for canine C3 deficiency is apparently not closely linked to the major histocompatibility complex of the dog. Thus, it appears that C3 deficiency in Brittany spaniel dogs not only shares biochemical and clinical features with C3 deficiency in humans, but also shares some genetic characteristics with the human disorder.

Primary pulmonary botryomycosis. A manifestation of chronic granulomatous disease.

A 19-year-old woman with a childhood history of cavitating left upper lobe pneumonia presented with persistent weight loss, fever, cough and roentgenographic evidence of right upper lobe pneumonia resistant to antibiotic therapy. An open lung biopsy led to the diagnosis of botryomycosis. Neutrophil function studies including flow cytometric evaluation of oxidative burst, bacterial killing and evaluation of neutrophil cytosolic proteins required for oxidase activation were consistent with chronic granulomatous disease. This is the first case report of primary pulmonary botryomycosis as a clinical manifestation of CGD. Other recent cases of immunodeficiency states associated with botryomycosis are reviewed.

Leukocyte depletion ameliorates free radical-mediated lung injury after cardiopulmonary bypass.

Activated leukocytes and oxygen free radicals have been implicated in the pathogenesis of lung injury associated with cardiopulmonary bypass. To determine whether leukocyte depletion could prevent this injury, we used a dog model simulating routine cardiac operations. Mongrel dogs (11 to 17 kg) were subjected to cardiopulmonary bypass with a bubble oxygenator and cooled to 27 degrees C. After aortic crossclamping and cardioplegic arrest for 90 minutes, control animals (n = 5) were rewarmed and weaned from bypass, and their condition was then stabilized for 90 minutes. Leukocyte-depleted animals (n = 5) had a leukocyte filter incorporated in the bypass circuit. During bypass, circulating leukocyte counts decreased by 60% in control dogs, and by 97% in leukocyte-depleted animals. Free radical generation (estimated by spectrophotometric assay of plasma conjugated dienes) was significantly reduced by leukocyte depletion during and after bypass. Total hemolytic complement activity and the titer of C5 decreased markedly immediately after the onset of bypass in both the control and leukocyte-depleted animals. Pulmonary function after bypass was better preserved in leukocyte-depleted animals. These data suggest that depletion of circulating leukocytes contributes to lung injury during cardiopulmonary bypass and is associated with increased oxygen radical activity, pulmonary edema, and vasoconstriction. Leukocyte depletion substantially reduced the pulmonary injury seen after cardiopulmonary bypass.

Heparin-coated bypass circuits reduce pulmonary injury.

Heparin coating of the extracorporeal circuit not only reduces heparin requirements during cardiac operations but also may reduce organ injury associated with cardiopulmonary bypass (CPB). To examine this possibility, pulmonary injury and neutrophil adhesion molecule expression after CPB were studied in pigs undergoing CPB with a standard extracorporeal circuit (group S, n = 6) or a heparin-coated CPB circuit (Carmeda BioActive Surface) (group HC, n = 6). Pigs received heparin sodium (300 U/kg intravenously) and then underwent 90 minutes of hypothermic (28 degrees C) CPB using membrane oxygenators, followed by 2 hours of observation. Blood samples were obtained for determination of neutrophil number and expression of the neutrophil adhesion molecule subunit CD18 (by immunofluorescence flow cytometry). The CPB-associated injury was less in group HC. Two hours after CPB, the arterial oxygen tension group was higher in group HC (597.2 +/- 31.2 versus 220.5 +/- 42.3 mm Hg; p < 0.0001), the pulmonary vascular resistance was lower in these animals (408.6 +/- 69.4 versus 1,159.8 +/- 202.4 dyne.s.cm-5; p = 0.02), and the static compliance was higher in group HC (66.4 +/- 5.4 versus 39.8 +/- 5.8 mL/mm Hg; p = 0.004). After 60 minutes of CPB, both groups had similar increases in expression of the neutrophil adhesion molecule subunit CD18 (29.4% +/- 19.5% versus 26.0% +/- 24.4%, group S and group HC, respectively) and similar decreases in neutrophil counts (6,056 +/- 1,285 to 2,453 +/- 979 cells/microL versus 6,010 +/- 1,748 to 3,197 +/- 1,225 cells/microL, group S and group HC, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Complement and neutrophil activation during cardiopulmonary bypass: a study in the complement-deficient dog.

Cardiopulmonary bypass (CPB) is known to cause complement and neutrophil activation, but the relative importance and interaction of these components in CPB-induced inflammation is unknown. In this study, a strain of dogs genetically deficient in the third component of complement (C3) was used to determine the contribution of C3 to neutrophil activation and pulmonary injury after CPB. Eleven dogs (5 C3-deficient and 6 controls) underwent 150 minutes of hypothermic CPB (28 degrees C) followed by 2 hours of observation. Before CPB, C3 levels were normal in controls and less than 1% of normal in C3-deficient dogs. In control dogs, functional activity of C3 decreased to 53.2% of baseline after 1 hour of CPB and there was immunohistochemical evidence of C3 deposition in lung after CPB; C3-deficient dogs had no C3 deposition in lung. Although similar degrees of neutropenia occurred during CPB in the two groups, expression of neutrophil adhesion molecule subunit CD18 was significantly lower in C3-deficient dogs than controls after 1 hour of CPB (45.9 +/- 3.7 versus 82.9 +/- 10.0 mean fluorescence units; p < 0.02). Postbypass lung tissue myeloperoxidase content was also less in C3-deficient dogs (43.8 +/- 4.6 versus 71.1 +/- 8.6 mumol x 10 mg-1 x min-1; p < 0.03). Cardiopulmonary bypass-associated lung injury (assessed by alveolar-arterial oxygen gradient, pulmonary vascular resistance, percent lung water, and light and electron microscopic appearance) was similar between groups. These results demonstrate that (1) C3 is deposited on pulmonary vascular endothelium during CPB and (2) C3 mediates increased expression of neutrophil CD18 and neutrophil sequestration in lung after CPB.(ABSTRACT TRUNCATED AT 250 WORDS)