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PubMed1983

Phagocytosis inhibits the production of C2 by human monocytes.

Production of the second complement component by cultured human monocytes was suppressed by the addition of a variety of phagocytosable particles. The degree of suppression was related to the concentration of particles, but was unrelated to particle size, the presence of surface sialic acid, antibody or C3b. The failure to reverse suppression by prostaglandin synthetase inhibitors indicates that it is not mediated by prostaglandins.

Cells, Cultured↗
PubMed1986

Bronchoalveolar lavage fluid and serum complement activity in pulmonary sarcoidosis.

In this work, using bronchoalveolar lavage fluids (BALF), we demonstrated the presence of complement within airways by assaying hemolytic activity of the whole classical pathway (CH50) and by measuring the complement component C2 (C2H50). Patients with sarcoidosis, patients with idiopathic pulmonary fibrosis (IPF), and healthy control subjects were compared. No CH50 activity was found in BALF from healthy control subjects (n = 9), but some activity (mean, 20 CH50) was associated with IPF (n = 7). Complement activities ranged from 40 to 554 CH50 in patients with sarcoidosis (n = 27). During the treatment, complement activity decreased in BALF from the few patients in our series who received corticotherapy. C2 hemolytic activity was detected in BALF from the normal control group (in the absence of CH50 activity). In the sarcoidosis and IPF groups when CH50 was present, the variations in the C2/CH50 ratio were studied. The high ratio observed in BALF from patients with sarcoidosis and a chronic derangement of alveolar structure suggests either an increased C2 production or an alternative complement pathway (C2-independent) activation within their lungs.

Adult↗
PubMed1984

Cleavage of C2 in pathological serum and plasma studied by crossed immunoelectrophoresis.

A cleavage product of C2, C2a was demonstrated by crossed immunoelectrophoresis in serum and EDTA plasma from patients with active systemic lupus erythematosus (SLE), patients in the early phase of acute poststreptococcal glomerulonephritis (AGN), and from two males with congenital deficiency of C1(-) inactivator, one of whom had symptoms of hereditary angioedema. C2a was not found in normal serum and plasma. C2 was more stable in plasma than in serum with regard to the effects of storage in room temperature and of repeated freezing and thawing. C2a concentrations were higher in serum than in plasma samples from SLE and AGN patients. Expressed in per cent of the total C2 protein, C2a was inversely correlated (r = -0.91) with the C2 hemolytic activity in the samples, which explains discrepancies between the results of immunochemical and functional assays, when used to measure C2 concentrations in disease.

Adult↗
PubMed1981

Cyclic AMP-mediated modulation of the production of the second component of human complement by monocytes.

The production of the second complement component (C2) by human monocytes in culture was inhibited by increasing their intracellular concentrations of cAMP following the addition to the culture medium of dibutyryl-cyclic AMP, 8-bromo-cyclic AMP, theophylline, isobutylmethylxanthine, cholera toxin or adenosine. The effects were not due to cytotoxicity or loss of cells from the monolayers, and therefore must reflect a decreased synthesis of section of C2. Although dibutyryl-cyclic GMP enhanced C2 production, 8-bromo-cyclic GMP, ascorbic acid and sodium nitroprusside did not have this effect. These observations suggest that the action of dibutyryl-cyclic GMP is not due to elevation of cyclic GMP levels and that cyclic GMP levels do not play a major role in C2 production by monocytes.

Bucladesine↗
PubMed1983

Complement studies in splenectomized patients.

Total haemolytic complement activity, C2, C5, total alternative pathway activity, factor B, and C3d were measured in 85 splenectomized patients from 1 month to 32 years after splenectomy. Furthermore the patients were investigated for circulating immune complexes. No major deficiencies of the complement factors were detected. In a few patients a reduced C2 level was caused by genetically determined defects or was due to complement consumption in conjunction with circulating immune complexes. The complement levels were normal in 2 patients who had survived overwhelming infections after splenectomy. C5 was elevated in a major proportion of the patients, and it is suggested that this might be caused by post-splenectomy monocytosis. Circulating immune complexes were found in 20% of all cases, irrespective of the presence of residual splenic tissue. Thus the commonly cited impairment of the complement system after splenectomy does not seem to be substantiated, and the deficient resistance against bacterial infections in splenectomized patients does not seem to include abnormalities of the complement system.

Adolescent↗
PubMedDate not supplied

Selective deficiencies in complement component : a family with hereditary C2 deficiency.

We report herein a new case of C2 deficiency in a patient with systemic lupus. The subject and one of her brothers, who shows no clinical manifestations, are hymozygous C2 deficient. All other family members are heterozygous for the C2 deficiency. Gene for C2 deficiency (C2d) was shown to be inherited with HLA-A9, B7/Bfs and HLA-A10, B27/Bfs haplotypes. This association has not previously been described.

Adolescent↗
PubMed1977

Cleavage of C2 by C1s into the antigenically distinct fragments C2a and C2b: demonstration of binding of C2b to C4b.

The activation of complement component C2 by C1s is a major reaction step leading to the assembly of two related macromolecular enzymes in the classical complement pathway C3 convertase and C5 convertase. The present studies clearly document the smaller fragment, C2b, that results when human C2 reacts with C1s. We have identified and characterized C2b (34,000 daltons) as a single protein on disc electrophoresis and immunoelectrophoresis. C2a (73,000 daltons), the larger fragment from this reaction, has a more acidic nature and C2b is more basic. These fragments can also be detected by their different antigenic determinants. When the C2-C4b complex is activated in the fluid phase by C1s and allowed to decay, it dissociates into C2a and the C2b-C4b complex. Furthermore, when C2 is bound to C4b-Sepharose and then reacted with C1s, only the C2a fragment is released from the solid phase C2-C4b-Sepharose into the fluid phase, and the C2b fragment remains noncovalently bound to C4b-Sepharose. These results suggest that the C2b portion of C2 contains a stable binding site for C4b and, after the decay release of C2a from this C3 convertase, the C2b fragment remains bound. Thus, the decay release of C2a may represent a temperature-dependent dissociation from C2b.

Binding Sites↗
PubMed1985

Immunofixation for C2 typing: C2 allotypes in Spaniards in relation to HLA, Bf and C4.

C2 typing is performed by immunofixation with anti-C2 antiserum instead of by a hemolytic overlay. This method gives sharp band definition, is less cumbersome than the hemolytic overlay, gel files are easily made, and it also enables one to describe putative new nonhemolytic variants. C2 allele frequencies were studied in a sample of the normal Spanish population and were found to be similar to other Caucasoids. HLA-Bw62,-Cw3, and -DR4 were significantly associated with C2 B. Concordantly, the only C2*B extended HLA haplotype found in family material was Bw62-Cw3-Bw6-(DR4)-Bf*S-C2*B-C4A*3 B*2-(GLO*1). C4A*4 B*2 and C4A*4 B*4 are not found within the same haplotype together with C2*B and Bw62 or Bw22 respectively, nor do other C2*B haplotypes occur with common HLA-B alleles. These results may favour the hypothesis that the Bw62-C2*B haplotype is produced by one mutation arising in the Bw62-C2*C haplotype and that subsequent crossovers can explain other C2*B haplotypes (including Bw22-C2*B).

Alleles↗
PubMed1992

Investigation of allotypes of HLA class III (C2, BF and C4) in patients with schizophrenia.

The allotypes of HLA Class III (C2, BF and C4) in 60 patients with schizophrenia were investigated. Significantly higher frequencies of BF*F, BF*SO7 and C4A*4 in patients were found as compared with those of the normal controls. The relative risks (RR) of the three allotypes to schizophrenia were 1.81, 7.79 and 4.18 and the etiologic fraction (EF) were 0.086, 0.060 and 0.042, respectively. There were no significant changes of C2 allotypes.

Complement C2↗
PubMed1982

Polymorphism of properdin factor B in Japanese. Description of a rare variant and data of association with HLA and C2.

Polymorphism of the properdin factor B (BF) was investigated using an agarose gel immunofixation electrophoresis in 487 unrelated healthy adult Japanese who were already typed for HLA-A, -B, -C and C2. Besides the previously reported phenotypes in Japanese (S, FS, and F), a rare heterozygous phenotype (tentatively maned FTS) was observed once. The estimated allele frequencies for BS*S, BF*F, and FB*FT (F Tokyo) were 0.801, 0.198, and 0,001 respectively. The relative electrophoretic mobility of the variant band of type FTS was measured by Dr. G Mauff to be F 0.75. The conversion fragment Bb of the type showed a double-banded pattern. BF hemolytic activity of the FTS individual was at the same level as other phenotypes. Statistical tests for the phenotypic data of BF with HLA-A, -B, -C, and C2 indicated the presence of the following significant associations in Japanese: Aw33-BF*F, A11-BF*S, Aw24-BF*S, B15-BF*F, B17-BF*F, Bw44-BF*F, B7-BF*S, Bw52;-BF*S, BW54-BF*S, BW59-BF*S, Cw3-BF*F, C2*AT-BF*F, and C2*A'-BF*F.

Adult↗
PubMed1976

HLA antigen studies in a family with C2 deficiency.

Two children in a family were found to be homozygous for C2 deficiency; both parents and a third child were heterozygous. C2 deficiency was associated with the HLA haplotypes carrying the antigens B18 and DW2. Antigen A10 was absent in this family. Mixed lymphocyte culture studies among the family members confirmed the association of C2 deficiency with the HLA-D locus.

Adult↗