Biomedical subjects

J Forristal

Publications and source records attributed to J Forristal.

At least 19 recordsLinked to original sources

PubMed1995

Level of receptor-associated protein moderates cellular susceptibility to pseudomonas exotoxin A.

Pseudomonas exotoxin A (PE) enters mammalian cells via a receptor-mediated endocytic pathway. The initial step in this pathway is binding to the multiligand receptor termed the alpha 2-macroglobulin receptor/low-density lipoprotein receptor-related protein (LRP). Binding of toxin, and of the many other ligands that bind to LRP, is blocked by the addition of a 39-kDa receptor-associated protein (RAP). Here we show that approximately 40% of the cell-associated LRP is on the surface of toxin-sensitive mouse LM fibroblasts and thus accessible for toxin internalization. The remainder is located intracellularly, primarily in the Golgi region. Mammalian cells exhibit a wide range of sensitivity to PE. To investigate possible reasons for this, we examined the expression levels of both LRP and RAP. Results from a variety of cell lines indicated that there was a positive correlation between LRP expression and toxin sensitivity. In the absence of LRP, cells were as much as 200-fold more resistant to PE compared with sensitive cells. A second group of resistant cells expressed LRP but had a high level of RAP. Thus, a toxin-resistant phenotype would be expected when cells expressed either low levels of LRP or high levels of LRP in the presence of high levels of RAP. We hypothesize that RAP has a pivotal role in moderating cellular susceptibility to PE.

ADP Ribose Transferases↗

PubMed1994

Serum complement levels before and after the onset of acute post-streptococcal glomerulonephritis. A case report.

Low serum C3, properdin, and C5 levels found in the acute stage of acute post-streptococcal glomerulonephritis (APSGN) indicate the presence of aggressive complement activation. We followed serum complement component levels in a child hospitalized with erysipelas who developed APSGN on the 2nd hospital day. Her initial serum sample, obtained prior to the clinical onset of nephritis, had a low properdin level and normal C3 and C5 levels despite the presence of C3 splitting activity. Two days later she developed gross hematuria and subsequent sera contained low C3, properdin, and C5 levels, as is usual in APSGN. These observations suggest that complement activation, predominantly through the alternative pathway, precedes the clinical onset of APSGN.

Acute Disease↗

PubMed1991

Isolation and characterization of Pseudomonas aeruginosa exotoxin A binding glycoprotein from mouse LM cells.

A Pseudomonas aeruginosa exotoxin A (PE) binding glycoprotein was affinity purified from toxin sensitive mouse LM cells. The binding protein was solubilized with Triton X-100 or Nonidet P-40 and purified on a PE-Sepharose affinity column. Polyacrylamide gel electrophoresis yielded a single band with an estimated molecular mass of greater than 300,000 Da. N-Linked carbohydrate was present, accounting for approximately 10% of the total mass of the molecule. The purified protein specifically bound PE. Incubation of purified protein specifically bound PE. Incubation of purified PE binding protein with toxin reduced toxicity to LM cells. We speculate on the role of this toxin binding glycoprotein in the intoxication process.

ADP Ribose Transferases↗

PubMed1990

Autoantibody to complement neoantigens in membranoproliferative glomerulonephritis.

With the exception of C3 nephritic factor, autoantibody formation has not been commonly associated with membranoproliferative nephritis (MPGN). We measured autoantibodies (nephritic factors) to the C3 convertases C3bBb (NFa) and C3bBbP (NFt), which result in fast and slow C3 activation, respectively, and to a neoantigen on C1q fixed to a solid phase (spC1q) in sera from 29 patients with MPGN type I, 26 with type II, and 28 with type III. Autoantibody formation was common in all MPGN types. An autoantibody to a C3 convertase neoantigen was identified in more than 75% of the hypocomplementemic MPGN sera tested. Anti-C3bBb (NFa) was present in 81% of patients with MPGN type II but was rarely found in either type I or type III. Anti-C3bBbP (NFt) was common in both MPGN I and III. Anti-spC1q was present in 74% of patients with type I and in 38% and 48% of types II and III MPGN, respectively. Patients with MPGN types I, II, and III had one and two serum autoantibodies detected significantly more frequently than did a group of healthy subjects. The presence of any one autoantibody was not specifically associated with the presence of any other autoantibody. The results indicate that multiple autoantibody formation is common in all MPGN types. MPGN II, and possibly MPGN I, tend to form more specific autoantibodies.

Antigen-Antibody Complex↗

PubMed1990

Patterns of complement activation in idiopathic membranoproliferative glomerulonephritis, types I, II, and III.

Complement profiles on 22 hypocomplementemic patients with membranoproliferative glomerulonephritis (MPGN) type I, on 11 with MPGN II, and on 16 with MPGN III, gave evidence that the nephritic factor of the amplification loop (NFa) is responsible for the hypocomplementemia in MPGN II and the nephritic factor of the terminal pathway (NFt) for the hypocomplementemia in MPGN III. In contrast, in MPGN I, there was evidence for three complement-activating modalities, NFa, NFt, and immune complexes. As a result, four different patterns of complement activation were seen. NFa, found in MPGN II, produces a complement profile characterized mainly by C3 depression. In addition, four of seven (57%) severely hypocomplementemic MPGN II patients (C3 less than 30 mg/dL) had slightly depressed levels of factor B, and one of seven (14%) of properdin, but in all the C5 concentration was normal. In contrast, all eight severely hypocomplementemic patients with MPGN II had depressed C5 and properdin levels, and six of eight (75%) depressed levels of C6, C7, and/or C9. Of eight MPGN III patients with moderate hypocomplementemia, 50% had depressed C5 and properdin levels and the remainder, depressed C3 only. This spectrum of profiles is most likely produced by varying concentrations of NFt. In MPGN I, nine of 23 (39%) had a profile indicating only classical pathway activation; seven of 23 (39%), a pattern compatible with NFt alone; four of 23 (9%), evidence for both classical pathway activation and NFt; and three of 23 (13%), a pattern compatible with NFa. The unique multifactorial origin of the hypocomplementemia in MPGN I, often giving evidence of classical pathway activation, together with previously reported differences in glomerular morphology and clinical features at onset, makes it distinct from MPGN III. Depressed C8 levels were found to some extent in all hypocomplementemic states. The levels were uncommonly depressed in patients with NFa, most markedly depressed with NFt, and moderately reduced with classical pathway activation. The cause is not known. Diagnostically, profiles showing classical pathway activation and low levels of C6, C7, and/or C9 are specific for MPGN I. Those showing only classical activation are likewise diagnostic of MPGN I if systemic lupus erythematosus (SLE) and chronic bacteremia are ruled out.

Complement Activation↗

PubMed1989

Serum terminal complement component levels in hypocomplementemic glomerulonephritides.

Measurements of serum C3 through C9 are reported for patients with acute poststreptococcal glomerulonephritis (AGN), membranoproliferative glomerulonephritis type I (MPGN I), MPGN II, and MPGN III. Except in MPGN II, depressed C5 levels correlated with depressed C3 levels. In MPGN II, levels of C5 and of other terminal components were normal. In MPGN III, markedly depressed levels of C7 through C9 correlated strongly with depressed levels of C3 and C5. C6 was less severely depressed. In MPGN I, terminal component levels were less often depressed than in MPGN III and in AGN, depression of terminal components was seen only when levels of C3 and C5 were extremely low. The data indicate that late terminal components are activated in MPGN III to a greater extent than in the other nephritides despite C5 activation approximately equal in extent to that in AGN and MPGN I.

Acute Disease↗

PubMed1989

A properdin dependent nephritic factor slowly activating C3, C5, and C9 in membranoproliferative glomerulonephritis, types I and III.

The IgG fraction of serum from patients with membranoproliferative glomerulonephritis (MPGN) types I and III was found to contain a nephritic factor (NFI/III) which differed from that usually present in MPGN type II and partial lipodystrophy (NFII) in that it converts C5 and C9 as well as C3, is dependent on properdin for its activity, and requires an incubation period of several hours rather than 30 min for its demonstration. C3 conversion occurred in the absence of an intact classical pathway. This nephritic factor was found in patients with reduced serum levels of terminal components and its activity, like that of the nephritic factor in MPGN type II, correlated with the serum C3 level indicating that these nephritic factors play a large role in producing hypocomplementemia. Although potentially nephritogenic because of its ability to activate the terminal pathway, the presence of this nephritic factor did not clearly correlate with clinical course.

Complement Activation↗

PubMed1988

Complement profiles in acute post-streptococcal glomerulonephritis.

It is well known that the hypocomplementemia of acute post-streptococcal glomerulonephritis (APSGN) is characterized by markedly reduced serum concentrations of C3 and moderately reduced levels of C5 and properdin (P). However, the extent of the activation of the classical pathway is not well defined and only limited data are available concerning serum concentrations of terminal components other than C5. In serial serum specimens from 14 children with APSGN, the presence and extent of C4 activation was directly assessed by measurement by rocket immunoelectrophoresis for C4 and C4 (C4d/C4 ratio). Elevated values for this ratio, indicating C4 activation, were found in 8 of 14 of the initial serum specimens, and in some patients the ratio remained elevated for several weeks. In contrast, the serum C4 level was low in only 1 specimen (the specimen with the highest C4d/C4 ratio). However, in 10 patients C4 concentrations within the normal range rose in serial serum specimens. Serum C2 concentrations were depressed in the initial specimens from 5 patients. The concentrations of 13 other complement component and control proteins were also measured in these specimens. Levels of terminal components, other than C5, in the initial serum specimens were normal except for depressed C8 in 3 of 13 patients and depressed C6 in 1 of 14. Of these 4 individuals, 3 had the lowest C3 levels in the study. It is concluded that the classical complement pathway is frequently activated in patients with APSGN early in the condition and that subtle abnormalities in C6 and C8 levels occasionally occur.

Adolescent↗

PubMed1987

Differences between membranoproliferative glomerulonephritis types I and III in clinical presentation, glomerular morphology, and complement perturbation.

Data for 26 patients with membranoproliferative glomerulonephritis, type I (MPGN I) and 22 with membranoproliferative glomerulonephritis, type III (MPGN III), as distinguished by glomerular ultrastructure, were analyzed to determine differences in presentation, complement perturbation, and glomerular morphology by light microscopy. MPGN III was detected with greater frequency by the chance discovery of hematuria and proteinuria in the otherwise healthy individual (MPGN III, 63%; MPGN I, 30%; P = .01) and never, in the absence of renal failure, presented with systemic symptoms such as ease of fatigue, weight loss, and pallor, as may patients with MPGN I. The more frequent detection of MPGN III by chance is evidence that its onset is insidious and that for long periods it produces no symptoms or signs. Glomerular proliferation is also less than in MPGN I. Further, in MPGN III, the complement perturbation and glomerular immunofluorescence give no evidence of classical pathway activation, for which there is abundant evidence in MPGN I. Even with severe hypocomplementemia in MPGN III, C3 nephritic factor, another cause of hypocomplementemia, is rarely detectable and then in very low concentration. The cause of the complement perturbation in MPGN III has so far escaped identification. Although these observations give evidence that MPGN III is distinct from MPGN I, there is compelling evidence from other studies that a predisposition to both types is inherited and that similar genetic factors are operative in the two types. Because their genetic basis appears to be the same, it must be concluded that despite their differences, types I and III are variants of the same disease.

Complement C3↗

PubMed1987

Hypocomplementemic glomerulonephritis in an infant and mother. Evidence for an abnormal form of C3.

A mother developed hematuria during the fourth month of pregnancy, and her nursing infant son from this otherwise uncomplicated pregnancy developed hematuria at 3.5 months of age. Both had a mild glomerulonephritis characterized by mesangial prominence, focal thickening and mottling of the glomerular basement membrane and electron-dense deposits, predominantly in the intramembranous and subendothelial positions. Immunofluorescence studies revealed striking accumulations of C3 and other complement components associated with alternative complement pathway activation within glomeruli, and the presence of small or equivocal amounts of immunoglobulin. C1q, C4 and factor B were not detectable. The glomerular lesion was accompanied by hypocomplementemia. Sera of both mother and infant displayed half normal levels of C3 and factor B, increased levels of C4, and normal levels of 12 other complement proteins. High normal or slight elevation in nephritic factor-like activity was observed in serial serum samples. Studies suggested that this mother and son represent the second kindred having an abnormal form of C3 which produces an alternative complement pathway C3 convertase, C3b, Bb, resistant to control by factor H. No additional affected family members were identified. The course of the nephritis over 7 years without drug therapy has been mild with resolving hematuria and no abnormal proteinuria or decrease in creatinine clearance.

Adult↗

PubMed1987

Hereditary complement (C6) deficiency associated with systemic lupus erythematosus, Sjögren's syndrome and hyperthyroidism.

Results of clinical, serologic and histologic studies documenting an association between hereditary C6 deficiency and a connective tissue disease are provided. The propositus had systemic lupus erythematosus with prominent discoid features, Sjögren's syndrome and hyperthyroidism. Serum C6 was undetectable by radial immunodiffusion and hemolytic assays. Serologic and typing studies performed on 9 family members suggested an autosomal codominant transmission. No correlation with a specific HLA phenotype was established.

Complement C6↗

PubMed1987

C4 binding protein deficiency in a patient with atypical Behçet's disease.

Primary deficiency of the C4 binding protein (C4bp) was present in a patient with disease clinically resembling Behçet's disease. Her father and her sister were also deficient. This protein, as a cofactor for factor I, interferes with the assembly of, and accelerates the decay of, the classical C3 convertase. Thus, the deficiency favours C3 conversion by classical pathway activation. In addition to genital and oral ulceration, cutaneous vasculitis and synovitis, our patient had relapses complicated by angioedema, atypical for Behçet's disease. It is not clear whether her total disease, or only the complicating angioedema, was a consequence of the C4bp deficiency.

Adult↗

PubMed1986

Effect of the nephrotic syndrome on the concentration of serum complement components.

The concentration of 12 component and four control proteins of the complement system was measured in serum from 43 children with a nephrotic syndrome, which subsequently proved to be steroid-responsive, and from 13 children with focal glomerulosclerosis (FGS) and was compared with values from 197 normal subjects. Of classical pathway complement components, 40% of patients had low C1q levels and 20%, low C2 levels. Mean serum levels of C1s, C4, C1INH, and C4bp were elevated. Of alternative pathway components, factors B and I were low in one third, while levels of C3 and H were commonly elevated. Of the terminal components, only C8 and C9 were low. In five patients with FGS with hypoalbuminemia without edema, all component levels were normal. With the exception of C1q, C1s, and C8, high molecular weight (mol wt) components were in high concentration and low mol wt components in low concentration. The three exceptions may be explained by the subunit structure of C1 and C8. From a practical standpoint, the study indicates that edematous patients with a nephrotic syndrome may have low serum levels of C1q and C2, simulating classical pathway complement activation such as commonly occurs in glomerulonephritis. However, low levels of C4, and possibly C1s, can be used as indicators of classical pathway activation since their levels are not reduced by a nephrotic syndrome.

Adolescent↗

PubMed1986

Relationship between the component and regulatory proteins of the classical pathway C3 convertase.

A relationship was found between the sums of the component proteins of the classical pathway C3 convertase (C2 and C4) and their regulators (C4bp and 1) in 184 normal controls. The relationship was maintained in most patients with low levels of individual components resulting from congenital deficiency and urinary losses, as well as in most cord sera. On the other hand, classical pathway activation in membranoproliferative glomerulonephritis type I, systemic lupus erythematosus, hereditary angioneurotic edema, and bacteremia resulted in loss of this relationship. Patients with alternative pathway-mediated complement activation (membranoproliferative glomerulonephritis type II) had a normal relationship between the classical component and regulatory proteins. In situations in which classical pathway activation is suspected, simultaneous examination of C4, C2, C4bp, and I may be helpful.

Angioedema↗

PubMed1985

The effect of null C4 alleles on complement function.

C4 is encoded at two polymorphic genetic loci (C4A and B), and "null" or unexpressed alleles are relatively common. An increased frequency of nulls has been reported in a variety of diseases. In the present study, C4 allotypes and C4 hemolytic efficiencies (the ratios of functional to antigenic levels) were determined for a population of 75 normal unrelated individuals. Of these, 28 had three gene products (single null at C4A or B) while three had no expressed C4A products and three had no C4B products (homozygous null). Mean antigenic C4 levels correlated with the number of expressed gene products but there was a wide spread of individual values. Those homozygous null for C4A had greater, and for C4B less, hemolytic efficiency than those with four gene products. However, there was no difference in the in vitro kinetics of C3 convertase formation between homozygous null C4A or C4B individuals. Therefore, the presence of null genes for C4 does not appear to compromise complement function sufficiently to account for the reported disease associations. Some of the associations may result from the fact that null genes for C4, as part of an extended HLA haplotype, may be genetically linked to disease susceptibility.

Adult↗

PubMed1985

Atypical hypocomplementemic vasculitis syndrome in a child.

We report a patient who developed recurrent urticaria and angioedema at age 2 years, severe hypocomplementemic glomerulonephritis at 11 years, and end-stage renal disease at 14 years. His disease resembled the hypocomplementemic vasculitis syndrome but was atypical in its early age of presentation, severe hypocomplementemia, and progression to end-stage renal disease. Serum C1q levels were extremely low, and C4, C2, C3, and C5 levels were significantly reduced. Serum C1 inhibitor (C1INH) levels were slightly low, presumably from consumption. Circulating C1INH-C1r-C1s complexes were evidenced by reduced ratios of functional to antigenic C1INH and antigenic C1r to C1s. Family members had normal functional and antigenic levels of all complement components studied. The patient's serum, erythrocytes, platelets, and mononuclear cells did not activate complement when mixed with normal target serum. Absence of a circulating complement activator and the low serum C3 and C5 levels suggested the presence of a solid-phase complement activator, possibly related to renal or systemic vascular endothelium. As in patients with homozygous deficiencies of classical pathway components, a severe, prolonged, acquired C1q deficiency may have predisposed this patient to the development of glomerulonephritis.

Angioedema↗

PubMed1985

A circulating inhibitor of fluid-phase amplification. C3 convertase formation in systemic lupus erythematosus.

C3 nephritic factor (C3NeF) was used to assess the formation of the fluid-phase amplification convertase, C3b,Bb, in 37 serum specimens from 24 patients with systemic lupus erythematosus (SLE). C3b,Bb formation was measured by the concentration of Ba, released when C3b,B is activated. Incubation of normal human serum (NHS) with C3NeF accelerates C3b amplification loop turnover with the formation of large quantities of C3b,Bb. In contrast, sera from 22 of 24 patients with SLE formed little or no convertase when incubated with C3NeF. C3 conversion to C3b was commensurately reduced. The inhibition could not be attributed to depressed serum concentrations of C3, factor B, or classical pathway components. Inhibitor present in excess could be demonstrated in 23 of 34 specimens of SLE serum by mixing experiments. The spontaneous convertase formation that occurs when a portion of the serum H is inactivated with F(ab')2 anti-H was also shown to be inhibited in SLE serum. The inhibition was found, however, to be H dependent in that convertase formation was normal in SLE serum depleted of H. It is concluded that the C3b in most SLE sera is unusually susceptible to inactivation by H, but a functional abnormality was not demonstrable in either C3 or H isolated from SLE serum. The inhibition could be simulated in NHS by addition of heparin, 100 micrograms/ml. In vivo, inhibition of convertase formation could interfere with the solubilization and disposal of immune complexes by reducing the deposition of C3b on the immune complex lattice.

Complement Activating Enzymes↗

PubMed1983

Inherited complement component deficiencies in membranoproliferative glomerulonephritis.

Anecdotal reports of complement component deficiencies in patients with immune complex disease led to a systematic study of the levels of seven complement components in serum specimens from 178 patients with glomerulonephritis and 163 normal subjects. Deficiencies were found with significantly higher frequency (22.7%) among 44 patients with membranoproliferative glomerulonephritis (MPGN) types I and III, than among the normal subjects (6.7%, P less than 0.002) or among 134 patients with other glomerulonephritides (5.2%, P less than 0.001). The component deficiencies in MPGN were partial in nine patients and subtotal in one. They could not be ascribed to acquired hypocomplementemia or to a nephrotic syndrome. They were present over long periods, were found in family members, and involved C2, C3, factor B, C6, C7, and C8. Six were presumably the result of null structural genes, two were associated with a structurally abnormal component, and two were of unknown cause. The results give evidence that partial deficiency of one or more complement components is a factor predisposing to MPGN.

Adolescent↗