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PubMed1979

Hereditary C2 deficiency associated with common variable immunodeficiency.

Homozygous C2 deficiency in a 19-year-old boy was associated with variable immunodeficiency manifested by marked hypoimmunoglobulinemia and impaired antibody responses, normal circulating B lymphocytes, and subnormal T-cell functions. Neither antilymphocytic autoantibodies nor chromosomal abnormalities were found. Serum immunoglobulin levels were within normal limits in his parents and brother who were heterozygous for C2 deficiency. The patient's lymphocytes were homozygous at the HLA-D locus but expressed an antigen different from DW2.

Adult↗
PubMedDate not supplied

Hemostasis and the complement system in Argentine hemorrhagic fever.

The salient abnormalities of blood coagulation found in the acute phase of Argentine hemorrhagic fever (AHF) were thrombocytopenia, prolonged partial thromboplastin time activated with kaolin, low factor VIII:C activity concurrent with high levels of von Willebrand factor, and increased values of factor V. No evidence of disseminated intravascular coagulation (DIC) was observed. Therefore, the hemostatic abnormalities detected in patients with AHF could not be attributed to DIC. There was no correlation between severity of the disease and occurrence of impairment of coagulation. Complement activation was observed during the acute phase of AHF. There was reduction of total complement and C2 activity. Antigenic levels of C1q, C3, and C5 were low; level of C4 antigen was high. Degradation products of C3 and B were demonstrated before day 11. Experimental models of AHF were developed (guinea pigs, Callitrix jacchus). These models may be useful, but they reproduced only some of the features of blood coagulation and complement abnormalities described in human AHF.

Animals↗
PubMed1974

Serum heat-labile opsonins in systemic lupus erythematosus.

To study possible mechanisms responsible for the increased susceptibility to infection of patients with active systemic lupus erythematosus (SLE), a study of the serum heat-labile opsonic capacity (HLOC) in such patients was undertaken. With leukocytes from normal donors, the sera of 12 of 30 patients with active SLE demonstrated decreased HLOC for E. coli 075. The phagocytic activity was partially restored by normal serum, suggesting that decreased HLOC was responsible for the defective phagocytosis. While 8 of 10 patients with active SLE and concomitant infections showed deficient opsonic capacity to E. coli 075, only 4 of 20 such patients without infections showed the defect (P = 0.01). None of 12 patients with inactive disease had deficient opsonic capacity. Similar results were obtained with S. aureus 502A as the test bacterium. In the patients surviving infection, recovery of normal serum opsonic capacity was rapid and usually coincided with an increase of serum complement to normal levels. In three patients with active SLE and infection, the causative microorganisms were isolated and opsonic capacity for these organisms tested with the individual patients' sera. In each case, sera obtained at the onset of the infectious episode had low opsonic capacity when compared with normal sera. Serum C3 proactivator levels were low in 9 of 11 sera with deficient opsonic capacity. However, similar low values were found in other SLE sera with normal HLOC, suggesting that other factors of the opsonic system were also depleted. Addition of the classical complement components C1, C4, C2, C3, and C5 to sera with deficient HLOC failed to restore activity. Addition of pure C3 proactivator also failed to restore activity. However, addition of C3 proactivator together with 50 degrees C-heated normal serum restored activity, indicating that factors active at the early steps of opsonic activation via the alternative pathway of complement were necessary to restore opsonic activity. These findings indicate that in active SLE, a decrease of components of the alternate pathway of complement activation results in an acquired defect of serum HLOC and perhaps other related complement-mediated functions. This defect may be an important factor in the increased susceptibility to infections of patients with active systemic lupus erythematosus.

Complement C2↗
PubMed1987

C2 deficiency, moderately low IgG2 concentrations and lack of the G2m(23) allotype marker in a child with repeated bacterial infections.

C2 deficiency was demonstrated in an 11-year-old boy with a past history of recurrent purulent otitis media, pneumonia, H. influenzae meningitis and S. pneumoniae septicaemia. The major histocompatibility complex haplotypes present, A10, B18, DR2, BF*S, C2*QO, C4*A4, C4*B2 and A28, B18, DR2, BF*S, C2*Q0, C4*A4, C4*B2, were in accord with previous observations in C2 deficiency. The concentrations of C1q, C5, factor B and factor D were in the low normal range and the hemolytic activity of the alternative pathway was slightly decreased. In addition, the patient showed moderately low IgG2 concentrations and lacked the IgG2 subclass marker G2m(23). The findings indicate that the patient's susceptibility to bacterial infections may be due to C2 deficiency in combination with the presence of an IgG allotype associated with impaired antibody responses to carbohydrate antigens.

Bacterial Infections↗
PubMed1978

Evidence for a silent or null gene in hereditary C2 deficiency.

Three generations of a family with hereditary C2 deficiency were studied, Six members heterozygous for C2 deficiency were identified by serum C2 levels that were approximately 50% of normal C2 values and the identity was supported by HLA analysis. All six members with low C2 levels had only a single electrophoretic variant. Two of four children did not have the variant found in the parent from whom they inherited the partial C2 deficiency. It is inferred that the low levels of C2 result from the inheritance of a silent or null gene, C2D allelic with the structural genes controlling the electrophoretic variants.

Antigens↗
PubMed2005

Problems of cyclosporine absorption profiling using C2-monitoring.

UNLABELLED: The present study sought to validate the concept of C2 monitoring in 41 de-novo transplant patients treated with microemulsion of cyclosporine, mycophenolatesodium, steroids and basiliximab. RESULTS: After 6 months patient and graft survival was 98%, rejection rate was 19%. In the first week only a few patients achieved the suggested C2 levels (19% > 1500, 50% > 1200 ng/ml) despite an increased cyclosporine (CsA) dose. After 14 days 63% of patients reached C2 > 1500 ng/ml (83% C2 > 1200) despite decreased CsA dose. 35% of patients had intermittent high C0 (> 300) and low C2 (< 800), suggesting poor and/or slow absorption. Most of them suffered from CsA toxicity. There was a significant (p < 0.05) change of absorption as measured by C2/C0 leading to an increase of C2/dose. CONCLUSIONS: C2 monitoring may be useful to better estimate the CsA exposure in individual patients; however our results indicate some limitations of the current concept of C2 monitoring. Despite increase of dosage many patients do not reach the proposed levels. A significant proportion of patients are poor and/or slow absorbers. CsA toxicity may not be detected by C2 monitoring alone. With the use of basiliximab and mycophenolatesodium lower target levels seem to be sufficient.

Antibiotics, Antineoplastic↗
PubMed1977

Kinetics of staphylococcal opsonization, attachment, ingestion and killing by human polymorphonuclear leukocytes: a quantitative assay using [3H]thymidine labeled bacteria.

A method has been developed for studying quantitatively the separate processes of bacterial opsonization, phagocytosis, and killing by human polymorphonuclear leukocytes using [3H]thymidine labeled Staphylococcus aureus. Phagocytosis is determined by assaying for leukocytes-associated radioactivity after differential centrifugation and washing the leukocytes. Opsonization is studied by incubating bacteria with an opsonic source for varying durations and then adding leukocytes. By treatment of samples with the muralytic enzyme, lysostaphin, the attachment and ingestion phases of phagocytosis can be separated. Sampling for colony forming units after disruption of the leukocytes permits the measurement of bacterial killing. Using this method, differences in the kinetics of staphylococcal opsonization by normal and C2 deficient sera were defined, opsonic influences on the attachment and ingestion phases of pH agocytosis were delineated, and the influences of different opsonins and leukocyte populations on killing were determined.

Blood Bactericidal Activity↗
PubMed1981

[Familial Mediterranean fever, complement, cryofibrinogen, colchicine (author's transl)].

The components C1, C4, C2, C3 of the complement system were measured in a group of 24 patients with Familial mediterranean fever (F.M.F.). The presence of cryofibrinogen and its analysis was performed in the same patient. C4, C2, C3, were increased in the F.M.F. group. Cryofibrinogenemia was found in 42 p. 100 of the patients. The cryofibrinogen was composed of fibrin, fibrinogen and plasma fibronectin. The cryofibrinogen was less frequent in the group of patients treated by colchicine (p less than 0.02).

Adolescent↗
PubMed1995

Further identification of human plasma glycoproteins interacting with the galactose-specific lectin Jacalin.

In this report we show that Jacalin binds the heme-binding protein hemopexin and the C4b-binding protein sgp120 in human plasma. The interaction of Jacalin with hemopexin confirms that a single O-linked oligosaccharide is sufficient to mediate binding of a protein to this lectin. Retention of sgp120 by immobilized Jacalin demonstrated that this protein was O-glycosylated and, therefore, clearly different from another C4b-binding protein, the complement protein C2 which is physicochemically similar but exclusively N-glycosylated. In addition, Jacalin was also shown to bind several proteolytic enzymes which remain to be identified.

Amino Acid Sequence↗
PubMed1985

HLA and genetic predisposition to lupus erythematosus and other dermatologic disorders.

Human leukocyte antigen (HLA) associations with different clinical and serologic subsets of lupus erythematosus are providing important clues to genetic predisposition and pathogenesis. The evolving complexity of the HLA-D region is described, and currently recognized HLA-region associations with systemic lupus erythematosus, subacute cutaneous lupus erythematosus, homozygous C2-deficient lupus, Sjögren's syndrome, and the neonatal lupus syndrome are reviewed. The striking relationship between the Ro/SSA-La/SSB antibody responses and HLA-DR2 and DR3 are emphasized. Other dermatologic conditions associated with HLA are also noted.

Adult↗
PubMed1979

HLA-linked C2 deficiency in a Dutch patient with systemic lupus erythematosus.

A patient with systemic lupus erythematosus was studied whose blood serum on repeated occasions showed undetectable levels of haemolytic omplement (C). A detailed investigation of individual C components in the serum of the proposita and her family revealed the absence of functional C2 in the patient and half-normal values in the relatives. C4 levels in the family, but not in the patient, were above normal, whereas the levels of factor B were low in all cases. No abnormalities were noted in C3, C9, or C1INH. Tissue typing showed linkage of the C2-deficiency gene with the HLA-A10/B18 and A9/B18 haplotypes. No linkage with red cell antigens and no relationship with plasma kallikrein levels was found.

Adolescent↗
PubMed1989

Regulation of monocyte/macrophage C2 production and HLA-DR expression by IL-4 (BSF-1) and IFN-gamma.

IL-4 was originally described on the basis of its ability to co-stimulate the proliferation of resting B cells treated with anti-IgM. Recently, this cytokine has been shown to have other effects on mast cells, T cells, B cells, and macrophages. We studied the ability of IL-4 to regulate the production of C2 by human monocytes and monocytic cell lines and compared this with stimulation of HLA-DR expression, another recently described activity of IL-4. Responses to IL-4 were compared to IFN-gamma, a cytokine with both activities. IL-4 up-regulated C2 production by human monocytes and this effect was not inhibited by neutralizing anti-IFN-gamma antibody. IL-4 also stimulated C2 production by HL-60 cells that had been pre-treated with vitamin D3 to induce monocytic differentiation. IL-4 did not stimulate C2 production by U937 cells. IFN-gamma, in contrast to IL-4, stimulates C2 production by all three cell types. Although IL-4 increased C2 production by HL-60 cells we could not detect C2 mRNA by Northern blotting. However, co-stimulation of these cells with IL-4 and low concentrations of IFN-gamma resulted in an additive effect on C2 production and a greater increase in C2 mRNA than was seen with IFN-gamma alone. As reported by others, IL-4-stimulated HLA-DR expression by monocytes. In contrast to our findings regarding C2 production, stimulation of HLA-DR expression was inhibited by neutralizing anti-IFN-gamma mAb and IL-4 did not stimulate HLA-DR expression by U937 or HL-60 cells. IFN-gamma stimulated HLA-DR expression by all three cell types. These results identify IL-4 as an additional cytokine able to directly stimulate C2 production by human monocytes and by a monocytic cell line whereas IL-4 stimulation of HLA-DR expression by monocytes appears to be IFN-gamma dependent.

Antibodies↗
PubMed2003

C2_4_4 microheterogeneity and HLA Class I.

The microheterogeneity of the tetranucleotide repeat locus C2_4_4 situated in the HLA class I region (6p21.3) was investigated by sequencing 50 alleles in an Austrian population sample of 240 unrelated Caucasoid individuals. Several different sequences were found in alleles of the same length. Analysis of the associations between the sequenced C2_4_4 alleles and HLA class I showed a strong linkage disequilibrium between the C2_4_4*9 sequence variants and two different HLA class I haplotypes, as well as between the most common *17 sequence and one HLA-ABC haplotype. No clear cut association could be observed in C2_4_4*16 and *18. The results of this study demonstrate that the exclusive use of microsatellite polymorphisms for the definition of HLA haplotypes is generally not possible.

Alleles↗
PubMed1989

Biologic activity of a C2-derived peptide. Demonstration of a specific interaction with guinea pig lung tissues.

A synthetic peptide derived from the carboxy terminus of C2b has been investigated for its ability to induce the contraction of guinea pig lung parenchymal strips. This peptide is known to enhance vascular permeability in guinea pig and human skin, and to induce contraction of estrous rat uterus. This C2 peptide (C2 207-223) is active from 5 x 10(-5) M to 5 x 10(-4) M and is not tachyphylactic to itself. No cross-activity between C2 207-223 and C5a or C3a could be demonstrated. C2 207-223 is not inhibited by antihistamines or cyclooxygenase inhibitors. These data indicate that the peptide exerts its action via a mechanism distinct from those of the C3a and C5a anaphylatoxins.

Amino Acid Sequence↗
PubMed1994

Constitutive expression of TNF-alpha and -beta genes in mouse embryo: roles of cytokines as regulator and effector on development.

1. Using the RT/PCR method, we examined mRNA expression of several inflammatory factors in mouse embryos during mid-late embryonal development. mRNAs of tumor necrosis factor (TNF)-alpha, TNF-beta, their receptors (TNF-RI, TNF-RII), transforming growth factor (TGF)-beta, were expressed constitutively in most of the embryonic tissues. 2. While mRNAs of other factors, interleukin (IL)-1 alpha, IL-1 beta, IL-3, IL-6, granurocyte-colony stimulating factor (G-CSF), leukaemia inhibitory factor (LIF), and interferon (IFN)-gamma were only limitedly expressed. 3. The mRNAs of several complement components (C2, C3, C4, C5) and receptors (CR1, CR2) were also detected. Among them, the expression of C3 and CR1 were prominent. These results strongly support our idea that inflammation-like system play an important role to regulate embryogenesis.

Animals↗
PubMed1978

Defective yeast opsonization and C2 deficiency in atopic patients.

Twenty-seven per cent of atopic patients initially presenting with infantile eczema or hay fever were defective for yeast opsonization and 18% had low levels of C2; these deficiencies were mutually exclusive, suggesting that they are primary. Both defects were associated with each of four different atopic syndromes, some of which were related to certain HLA haplotypes.

Adolescent↗
PubMed2005

Pharmacokinetic of cyclosporine microemulsion in pediatric kidney recipients receiving A quadruple immunosuppressive regimen: the value of C2 blood levels.

BACKGROUND: The management of cyclosporine therapy in pediatric kidney-transplant recipients is largely based on single center's experience rather than on a univocal pharmacokinetic approach based on therapeutic drug monitoring. A prospective multicenter trial was designed to address the question whether C2 blood level monitoring of cyclosporine microemulsion therapy is feasible in the pediatric setting. METHODS: Sixty-four pediatric kidney-transplant recipients receiving a triple immunosuppressive regimen based on cyclosporine microemulsion had their cyclosporine dose adjusted to the same protocol-defined C2 targets from the time of the transplant until 2 years posttransplant. The interim analyses after 1 year of enrollment is presented in this study. RESULTS: One-year patient and graft survival were 100% and 94.8%, respectively. One-year rejection rate was 15%. C2 management of cyclosporine did not affect graft function: 1-year serum creatinine and glomerular filtration rate were 1.3+/-1 mg/mL and 71.2+/-20 mL/min/1.73 m2, respectively. C2 was the best single-point predictor of the area under the concentration curve throughout the entire follow-up, with a mean coefficient of correlation of 0.97+/-0.01. CONCLUSIONS: C2 management of cyclosporine microemulsion therapy is effective and safe in pediatric kidney-transplant recipients given a combined immunosuppressive treatment.

Adolescent↗
PubMed1977

Effect of concanavalin A on the classical complement pathway.

Lysis of sheep erythrocytes (E) sensitized with anti-Forssman antiserum (EA) is inhibited by the action of concanavalin A (Con A) on whole guinea pig complement (GPC). The degree of inhibition observed for a given quantity of GPC was dependent on the Con A concentration. Specifically, Con A inhibits the activity of the early acting complement components C1 and C2 in the fluid phase, but has no significant effect on lysis once these components are bound to EA. Results of tmax experiments performed in the presence or absence of Con A showed that inhibition of C2 activity results from a direct interaction between Con A and C2 and not from a decreased number of effective EAC14 sites. Furthermore, since Con A pretreated or untreated EAC14 cells had the same tmax value, Con A and C2 apparently do not compete for the same binding site on the indicator cells. The lectin has no observable effect on either fluid phase or cell-bound C4 activity. Under similar conditions, wheat germ or soy bean agglutinin, leucoagglutinin or pokeweed mitogen did not inhibit hemolysis.

Antibodies↗