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PubMed1989

Hydrodynamic, electron microscopic, and ligand-binding analysis of the Epstein-Barr virus/C3dg receptor (CR2).

The interaction of the Epstein-Barr virus/45-kDa proteolytic fragment of C3 (C3dg) receptor (CR2) with its viral ligand, the Epstein-Barr virus glycoprotein gp350/220, initiates the sequence of events leading to virus internalization and B lymphocyte transformation. Soluble recombinant receptor (rCR2) and gp350/220 as well as the natural ligand, C3dg, were subjected to a number of analytical techniques including gel permeation chromatography, density gradient ultracentrifugation, circular dichroism, and electron microscopy in order to determine their hydrodynamic, structural, and binding properties. Both rCR2 and gp350/220 were found to be highly extended proteins (f/fo = 2.1 and 2.4/2.2, respectively). C3dg, in contrast to the viral ligand, is only somewhat elongated (f/fo = 1.5). Soluble rCR2, visualized by high resolution electron microscopy, was shown to be an extended, highly flexible molecule comprised of ringlet domains, each approximately 24.1 A in length, which likely correspond to the short consensus repeat motif deduced from the CR2 cDNA nucleotide sequence. Ligand-binding studies carried out under physiological conditions indicated that gp350/220 binding to rCR2 was saturable and univalent, with a dissociation constant of 3.2 nM. In contrast, monomeric C3dg did not bind to rCR2 under physiological conditions; however, at reduced ionic strength, monomeric C3dg binding could be measured. These studies indicate that the affinity of the C3dg monomer for rCR2 under physiologic conditions is approximately 10(4)-fold less than that of the viral ligand. The molecular properties of rCR2 revealed in these studies provide essential information for future studies of the biologic functions of the Epstein-Barr virus/C3dg receptor.

Antigens, CD↗

PubMed2002

Modeling the presentation of C3d-coated antigen by B lymphocytes: enhancement by CR1/2-BCR co-ligation is selective for the co-ligating antigen.

We have used a set of single-chain variable fragment antibodies (sc) genetically fused with an influenza hemagglutinin-derived peptide as a means to investigate the role of CR1 and CR2 in antigen presentation by B cells. When incubated with the B cell lymphoma 2PK3, peptide-containing sc specific for either CR1 or CR1/2 mediated activation of the hemagglutinin peptide-specific T cell line IP-12-7, as assessed by IL-2 production. Efficient presentation was dependent on the binding of the constructs to CR1/2, implying that receptor-mediated endocytosis is responsible for the effect. Cross-linkage of CR1/2 or CD19 by mAb did not increase the extent of T cell activation. However, when CR1/2 was co-ligated with the BCR--using either polyclonal goat anti-mouse IgG or recombinant protein LA--the antigen concentration required to activate T cells decreased by two orders of magnitude. Moreover, this enhancement was selective for the antigen included in these complexes and did not affect the presentation of a free peptide or of antigen bound to CR1/2 excluded from the complexes. These results suggest that B cells may bind various C3d-coated antigens at a time, but only the one which reacts with the BCR will be processed with high efficiency. This mechanism may ensure the specificity of cognate T cell help.

Animals↗

PubMed1996

Activation of FXII during haemodialysis.

This study was designed to provide information on the kinetics of FXIIa activity and C3d release during haemodialysis. Dialysis was performed twice in 9 stable patient for 240 min with the same conditions except for a change in dialysate sodium profile (using a linear sodium programme starting at 138 and ending at 148 mmol/l or vice versa). Using paired statistics there was a significant (p < 0.02) increase in both C3d release and the FXIIa activity. The sodium profiles did not alter the outcome. The increase in FXIIa activity, which is maximal at the end of dialysis, is continuous, unlike the C3d release, which is maximal within 15 min of dialysis and then levels off. Both interactions are induced by the blood membrane contact. These results indicate that the FXIIa activation is not strictly coupled to the activation of the complement system.

Complement C3d↗

PubMed1983

Suppression of T lymphocyte functions by human C3 fragments. I. Inhibition of human T cell proliferative responses by a kallikrein cleavage fragment of human iC3b.

Cleavage of human iC3b by kallikrein isolated from human plasma generates a fragment, C3d-K, which is capable of inhibiting mitogen-, antigen-, and alloantigen-induced T lymphocyte proliferation. Native C3, C3a, C3b, and C3c-K had no effect on lymphocyte proliferative responses. In addition to being a potent suppressor of mitogen- and antigen-induced proliferation, C3d-K is capable of inducing leukocytosis in both mice and rabbits. Intravenous injection of C3d-K, but not C3, C3a, C3b, or C3c-K, results in a twofold to threefold increase in the number of circulating leukocytes. Thus, C3d-K exhibits two apparently independent functions, namely suppression of T cell proliferation and leukocytosis. Cleavage of iC3b by kallikrein results in the production of only two fragments. The larger fragment, C3c-K, is 144,000 m.w. and has a chemical structure analogous to that of C3c obtained from the cleavage of C3 by trypsin or elastase. The smaller fragment, C3d-K, is 41,000 m.w. and contains the metastable binding site of C3. It is through this site located in the C3d region of the molecule that C3 attaches covalently to target cells. Analysis of the amino terminal region of C3d-K provided a sequence that fails to overlap with any sequence yet reported for other characterized C3 fragments, including C3d originally obtained from elastase digestion. A revised model of the C3 molecule is proposed, with locations of the C3e and C3d fragments assigned on the basis of chemical analyses.

Adult↗

PubMed1993

Increased in vivo activation of neutrophils and complement in sickle cell disease.

Eight patients with homozygous sickle cell anemia, 15 heterozygotes, and eight control individuals were investigated with respect to plasma concentrations of the inflammatory markers lysozyme and myeloperoxidase and the complement activation marker C3d. The patients showed significantly increased levels of myeloperoxidase and C3d, but not lysozyme, compared with the heterozygotes and the controls. The heterozygotes were also significantly different from the controls with regard to C3d concentration. The concentrations of myeloperoxidase and C3d in plasma showed a significant inverse correlation with the hemoglobin concentration. Myeloperoxidase and C3d showed a significant positive correlation. This suggests a role for the neutrophil and the complement system in the pathophysiology of sickle cell disease.

Adolescent↗

PubMed2004

Functional differences in IgG anti-polysaccharide antibodies elicited by immunization of mice with C3d versus ovalbumin conjugates of pneumococcal serotype 14 capsular polysaccharide.

We previously have shown that conjugation of C3d to pneumococcal serotype type 14 capsular polysaccharide (PPS14) significantly enhances anti-PPS14 antibody production to a degree similar to that found when the T-dependent protein carrier ovalbumin (OVA) is coupled to PPS14. However, the anti-PPS14 antibody response to PPS14-C3d conjugates is characterized by less switching from IgM to IgG and lower serum concentrations of anti-PPS14 IgG after secondary immunization. To determine if these quantitative differences in anti-PPS14 IgG are accompanied by qualitative differences in the IgG anti-PPS14 antibodies, we performed several functional assays on serum IgG anti-PPS14 antibodies from mice immunized with PPS14-C3d or PPS14-OVA. Compared with antibodies elicited by immunization with PPS14-C3d, IgG anti-PPS14 antibodies produced after immunization with PPS14-OVA were found to have higher avidity and enhanced function as opsonins. Comparisons of avidity for IgG from serum samples obtained after primary and secondary immunization demonstrated a higher degree of avidity maturation after immunization with PPS14-OVA than with PPS14-C3d. These results suggest that PPS14-C3d conjugates are unlikely to be more efficacious than PPS14 conjugate vaccines incorporating T-dependent protein carriers.

Animals↗

PubMed2004

Contribution of C3d-P28 repeats to enhancement of immune responses against HBV-preS2/S induced by gene immunization.

AIM: To investigate whether P28 derived from C3d can enhance the immune response to HBV-preS2/S induced by directly injection of naked plasmids containing variable repeats of P28 and HBV-preS2/S in fusion form. METHODS: One to four copies of C3d-P28 coding gene, amplified by PCR and modified by restriction endonucleases digestion, were subcloned into a eukaryotic expression vector pVAON33 to construct pVAON33-P28, pVAON33-P28.2, pVAON33-P28.3 and pVAON33-P28.4 (pVAON33-P28.[1-4]). HBV-preS2/S coding sequence was then introduced into the pVAON33-P28.[1-4] and identified by both PCR and DNA sequencing. BALB/c mice were primed by intramuscular gene immunization with 100 microg different recombinant plasmids on day 0 and were boosted by subcutaneous inoculation with HBsAg protein (1 microg) 12 wk post-priming. The levels and avidity of specific IgG in sera collected at the indicated times from each group were determined by ELISA and NaSCN-displacement ELISA, respectively. RESULTS: HBsAg specific antibody response was elicited in groups primed with plasmids pVAON33-S2/S-P28.[1-4] and pVAON33-S2/S. However, the response against HBsAg in the groups primed with pVAON33-S2/S-P28.[1-4] was significantly higher than that in pVAON33-S2/S group, the highest level of the specific antibody response was observed in the groups primed with pVAON33-S2/S-P28.4 (P<0.01). After secondary immunization with specific antigen, the acceleration of antibody levels was significantly higher and faster in the mice primed with DNA expressing preS2/S-P28 fusions than that with DNA expressing preS2/S only (P<0.05). Interestingly, mice primed with DNA expressing preS2/S-P28.4 fusions maintained the highest levels of anti-HBs antibodies in all animals. The avidity assay showed that the avidity index (AI) collected at 18 wk from mice primed with pVAON33-S2/S-P28.3 and pVAON33-S2/S-P28.4 were significantly higher than that from preS2/S-DNA vaccinated mice (P<0.01). CONCLUSION: Different repeats of C3d-P28 can enhance both humoral immune response and avidity maturation of specific antibodies induced by gene immunization, in which four copies of C3d-P28 may be necessary to achieve the most modest antibody response.

Animals↗

PubMed2005

[C3d enhances the immune response against HBV-preS2/S following gene immunization in mice].

OBJECTIVE: To investigate whether C3d can enhance the immune response to HBV-preS2/S induced by direct injecting naked plasmid containing three copies of C3d and HBV-preS2/S in fusion form. METHODS: HBV-preS2/S coding sequence was introduced into the eukaryotic expression vectors TR421 and TR421-C3d3 containing 3 copies of C3d respectively. PCR was used to identify the direction of insertion, DNA sequencing analysis was used on the positive clones. The recombinant plasmids TR421-preS2/S and TR421-preS2/S-C3d3 were transfected into the human breast cancer cells of the line 4T1 as a transient expression system. Semi-quantitative RT-PCR was used to detect the expression of HBV-preS2/S protein. TR421-preS2/S and TR421-preS2/S-C3d3 were injected into the anterior tibial muscles of female BALB/c mice, 6 in each group, 3 times at an interval of 3 weeks. Six mice were injected with blank plasmid TR421 as controls. The total blood was collected from the mice. ELISA was used to detect the level of specific anti-HBs antibody. The splenocytes of the immunized mice were collected and stimulated with HbsAg protein and then harvested to analyze the specific lympho-proliferative response by (3)H-thymidine incorporation assay. CR2 positive Raji cells were added with plasmid transfected and mouse anti-HBs serum. Flow cytometry was used to detect the integration of preS2/S-C3d3 fusion protein. RESULTS: The 4T1 cells transfected with TR421-preS2/S and TR421-preS2/S-C3d3 effectively expressed HBV-preS2/S, with the expression level of TR421-preS2/S-C3d3 lower by 15.25% than that of TR421-preS2/S. Twelve weeks after immunization, the specific anti-HBs-IgG level (A(490nm)) was 0.81 +/- 0.09 in the TR421-preS2/S primed mice, significantly higher than that in the blank plasmid injected mice (0.49 +/- 0.02, P < 0.05); and the specific anti-HBs-IgG level (A(490nm)) was 1.24 +/- 0.29 in the TR421-preS2/S-C3d3 immunized mice, significantly higher than that of the TR421-preS2/S primed mice (P < 0.001). The lympho-proliferative response of the TR421-preS2/S primed mice was significantly stronger than that of the blank plasmid injected mice (P < 0.05) and the lympho-proliferative response of the TR421-preS2/S-C3d3 primed mice was significantly stronger than that of the TR421-preS2/S primed mice (P < 0.05). Surface binding of protein could be detected only in the TR421-preS2/S-C3d3 transfected supernatant. About 43.19% of the CR2 positive Raji cells integrated C3d fusion protein. TR421-preS2/S transfected supernatant and negative control did not show obvious integration. CONCLUSION: C3d enhances the humoral and cell-mediated immune responses against HBV induced by gene immunization.

Animals↗

PubMed2001

Enhanced avidity maturation of antibody to human immunodeficiency virus envelope: DNA vaccination with gp120-C3d fusion proteins.

DNA vaccination can elicit both humoral and cellular immune responses and can confer protection against several pathogens. However, DNA vaccines expressing the envelope (Env) protein of human immunodeficiency virus (HIV) have been relatively ineffective at generating high titer, long-lasting, neutralizing antibodies in a variety of animal models. In this study, we report that fusion of Env and the complement component, C3d, in a DNA vaccine, enhances the titers of antibody to Env. Plasmids were generated that expressed a secreted form of Env (sgp120) from three isolates of HIV and these same forms fused to three tandem copies of the murine homologue of C3d (sgp120-3C3d). Analyses of titers and avidity maturation of the raised antibody indicated that immunizations with each of the sgp120-3C3d-expressing DNAs accelerated both the onset and the avidity maturation of antibody to Env.

AIDS Vaccines↗

PubMed1987

Suppressive effects of C3b on monocyte-dependent T cell proliferation.

The effect of C3b treatment of human monocytes on secondary antigen-dependent T cell response was studied. When antigen-specific T cell blasts were cultivated together with C3b-treated monocytes the proliferative response was inhibited in a dose-dependent fashion. This suppressive effect was specific for C3b because heat-inactivated C3b or buffer alone had no influence on T cell proliferation. In part, this suppressive effect is mediated through a C3b-induced decreased expression of class II antigens on the surface of treated monocytes, but another suppressive mechanism exists because the C3b pretreatment of monocytes also led to an inhibition of the proliferative response in a class II antigen-independent T cell proliferation system. In addition to the C3b data, our finding that treatment of monocytes with C3d resulted in a lower T cell proliferation, while C3c has no effect, suggested that C3d, which could be generated from C3b in the culture, may induce the second inhibitory mechanism.

Cells, Cultured↗

PubMed1996

Function of C3 in a humoral response: iC3b/C3dg bound to an immune complex generated with natural antibody and a primary antigen promotes antigen uptake and the expression of co-stimulatory molecules by all B cells, but only stimulates immunoglobulin synthesis by antigen-specific B cells.

Previous studies have shown that an optimal humoral response to a primary protein antigen requires C3 and CR2 (CD21). Sera from non-immunized donors contain natural IgM and IgG antibodies to the primary antigen keyhole limpet haemocyanin (KLH), and these have been previously shown to form immune complexes (IC) that activate the classical pathway of C, fixing iC3b/C3dg onto the KLH antigen. Such KLH IC bind to CR2 on KLH-non-specific B lymphocytes, resulting in antigen processing and MHC class II-dependent presentation to KLH-specific helper T cells. KLH IC also induce B lymphocytes to express the CD80 costimulatory molecule via simultaneous CR2 ligation with C3 and Fc gammaRII (CD32) stimulation by IgG natural antibody. The current study demonstrated that KLH IC ligation to either CR2 or Fc gammaRII resulted in activation of a second co-stimulatory molecule, LFA-1 (CD11a, CD18). The possibility of polyclonal B cell stimulation by the presentation of KLH-iC3b/C3dg by antigen-non-specific B cells was excluded by demonstration that in vitro cultivation of peripheral blood mononuclear cells (PBMC) with KLH-iC3b/C3dg elicited only anti-KLH, and did not stimulate synthesis of antibodies to hepatitis C virus (HCV) or tetanus toxoid (TT). Of greatest significance, a specific anti-KLH response was only detectable in cultures stimulated with KLH-iC3b/C3dg and not in cultures stimulated with KLH alone or KLH-IgG. Thus, iC3b/C3dg that was bound to a primary protein antigen enhanced recognition and specific immunoglobulin synthesis by antigen-specific B cells, even though the antigen was taken up and processed via CR2 by both antigen-specific and non-specific B cells.

Antibodies, Monoclonal↗

PubMed2005

IgM colocalises with complement and C reactive protein in infarcted human myocardium.

AIMS: Reperfusion of ischaemic myocardium after acute myocardial infarction (AMI) can induce ischaemia/reperfusion (I/R) injury, as a result of local activation of the complement system. C reactive protein (CRP) is involved in this activation. This study analysed the potential role of IgM in complement activation in the infarcted human myocardium. METHODS: Immunochemical analysis was carried out on heart specimens from 59 patients who died from AMI. Serial slides of frozen tissue from the infarction site were stained for IgM, complement factors C3d and C5b-9 (membrane attack complex), and CRP. RESULTS: IgM deposits were found on the plasma membrane, cross striations, and in the cytoplasm of jeopardised cardiomyocytes in infarcts of one to five days duration. IgM depositions were remarkably similar to those of CRP and both complement factors. The relative staining intensities of IgM and CRP varied greatly among patients. CONCLUSIONS: Similar to CRP, IgM targets complement locally to jeopardised cardiomyocytes in the human heart after AMI. Localisation patterns and relative staining intensities suggest that IgM and CRP recognise similar epitopes in the ischaemic heart, but that the relative contribution of each protein to complement activation in the ischaemic myocardium differs among patients.

Adult↗

PubMed1986

Comparisons of pooled polyclonal rabbit anti-human C3d with four monoclonal mouse anti-human C3ds. I. Preparation, purification and binding properties.

Performance characteristics of pooled rabbit IgG polyclonal anti-C3d are compared with one mouse IgM and three mouse IgG monoclonal anti-C3d antibodies (MAs). IgG MA,s employed singly or in combination, failed to precipitate C3d; by contrast, IgM MA and polyclonal anti-C3d precipitated C3d. Measurements of polyclonal anti-C3d concentration by chemical means and by 125I-C3d radioimmunoassay (RIA) agreed closely. RIA values were 50% of chemical measurement values for three of the four MAs. Use of sucrose density gradient ultracentrifugation to assess MA C3d/anti-C3d molar combining ratios for soluble anti-C3d/C3d was not possible because fast-sedimenting multimeric C3d/anti-C3d complexes did not form. Dissociation and competitive binding studies indicate that (1) two MAs had substantially lower affinities than the other anti-C3d antibodies, and (2) polyclonal anti-C3d recognizes more C3d epitopes than are recognized by individual MAs. The results demonstrate antigenic complexity of C3d fragment and illustrate the difficulties of predicting individual MA performance based on prior experience with polyclonal antibodies.

Animals↗

PubMed1991

Pneumococcal polysaccharides complexed with C3d bind to human B lymphocytes via complement receptor type 2.

The immunoregulatory function of the complement system has been the focus of many investigations. In particular, fragments of complement factor C3 have been shown to play a role in B-lymphocyte activation and proliferation, lymphokine production, and the generation of in vitro antibody production. Purified pneumococcal polysaccharides (PS) can induce direct activation of C3 via the alternative pathway. Using sera of C1q-deficient patients and healthy subjects, we demonstrated that C3d, a split product of C3 that is generated after degradation of iC3b, can be bound to PS antigens. The binding of C3d to PS can occur in the absence of specific antibodies. Subsequently, we showed that PS complexed with C3d can be recognized by complement receptor type 2 that is expressed on B cells. Treatment of B cells with a monoclonal antibody recognizing the C3d-binding site of complement receptor type 2 reduces the binding of PS-C3d to the cells. In addition, we showed that PS4 complexed with C3d exerted an increased immunogenicity compared with free PS4. Our results show that the complement system plays a role in the activation of PS-specific B cells, carrying membrane receptors for C3d. Consequently, the complement system plays a regulatory role in the antibody response to T-cell-independent type 2 antigens such as PS.

Adult↗

PubMedDate not supplied

Radioimmunoassay evaluation of anti-C3d reactivity in broad spectrum commercial antiglobulin reagents.

The study was undertaken to assess the potential of a labeled C3d radioimmunoassay method as a standardization criterion for antiglobulin reagents containing anti-C3d reactivity. Over an 18-month interval, four different lots of broad-spectrum antiglobulin reagents were purchased from each of seven United States manufacturers. Anti-C3d antibody concentration and Ko in each lot were assayed initially and at four-month intervals over 16 to 21 months storage at 4 degrees C. The results permitted 1) comparison of anti-C3d antibody concentrations among different manufacturers, 2) comparison among different lots from the same manufacturer, and 3) assessment of stability of anti-C3d during storage. In addition, serial dilutions of reagents in each manufacturer's diluent were compared for their anti-C3d agglutinating properties by the spin-antiglobulin method against red blood cells (RBC) coated by C3d in vitro and against in vivo C3d-coated RBC from 16 patients. Most reagents were shown also to contain anti-C3c, anti-C4c and anti-C4d reactivities when tested against suitably coated RBC. Anti-C3d antibody concentrations ranged from approximately 1 to 3.5 microgram/ml for 27 of the 28 reagents and were stable over 16 to 21 months of storage. Anti-C3d agglutination titer scores showed a general correlation with anti-C3d antibody concentrations when tested against in vitro C3d-coated RBC; correlations were less good against C3d-coated cells from patients. The radioimmunoassay provided reproducible objective measurements and appeared to have merit as a standardization criterion.

Anemia, Hemolytic, Autoimmune↗

PubMed1995

The complement control protein homolog of herpesvirus saimiri regulates serum complement by inhibiting C3 convertase activity.

The herpesvirus saimiri genome encodes a complement control protein homolog (CCPH). Stable mammalian cell transfectants expressing a recombinant transmembrane form of CCPH (mCCPH) or a 5'FLAG epitope-tagged mCCPH (5'FLAGmCCPH) conferred resistance to complement-mediated cell damage by inhibiting the lytic activity of human serum complement. The function of CCPH was further defined by showing that the mCCPH and the 5'FLAGmCCPH transfectants inhibited C3 convertase activity and effectively reduced cell surface deposition of the activated complement component, C3d.

Amino Acid Sequence↗

PubMed2005

C3d enhances immune responses using low doses of DNA expressing the HIV-1 envelope from codon-optimized gene sequences.

DNA vaccinations effectively induce both humoral and cellular immune responses to immunogens from diverse infectious agents. However, DNA vaccines expressing the HIV-1 envelope glycoprotein (Env) are poorly immunogenic when expressed from wild-type (wt) DNA sequences. Two recent approaches used to enhance the immunogenicity of Env expressed from a DNA vaccine are the fusion of the molecular adjuvant, C3d, to a soluble form of Env and the use of codon-optimized (co) env gene inserts. Independently, each approach enhances antibody titer and cellular responses against Env expressed from gene inserts. The goal of this study was to examine if both codon-optimization of env gene inserts and C3d conjugation to Env could function in a synergistic manner to enhance immunogenicity. Mice (BALB/c) were inoculated with decreasing doses (2.0 microg, 0.2 microg or 0.02 microg) of co DNA expressing Env alone or fused to three copies of murine C3d (mC3d3) gene. Mice vaccinated with the highest dose (2.0 microg) of DNA had high anti-Env specific antibody titers regardless of the addition of mC3d3. At lower doses (0.2 microg and 0.02 microg) of DNA, mice vaccinated with Env-mC3d3 had enhanced immune responses compared to mice vaccinated with DNA expressing Env only. In addition, mice vaccinated with Env-mC3d3 at the highest doses of DNA had enhanced interleukin-4 secreting cells, while mice vaccinated with the lowest dose of DNA had enhanced interferon-gamma secreting cells. Therefore, both codon-optimization of env sequences and C3d conjugation to Env appear to enhance anti-Env antibodies in an independent and additive manner.

AIDS Vaccines↗

PubMed1996

Tumor-specific deposition of immunoglobulin G and complement in papillary thyroid carcinoma.

Despite its predilection for multifocal growth and regional metastasis, papillary thyroid carcinoma (PTC) is a clinically indolent malignancy with an exceptionally favorable long-term prognosis. Together with the often striking inflammatory reaction present in PTC, its quiescent behavior has been suggested to reflect the activation of a tumor-induced immune response. To examine this possibility, we have studied the deposition of immunoglobulins and complement in PTC tissue. Samples from 70 cases of neoplastic and autoimmune thyroid diseases, including PTC (n = 41), follicular, anaplastic, and medullary carcinomas (n = 12), follicular adenoma (n = 6), Graves' disease (n = 8), and Hashimoto's thyroiditis (n = 3) were analyzed immunohistochemically. Cellular deposits of immunoglobulin G (IgG), particularly subclasses IgG1 and IgG4, and complement factors C3d, C4d, and C5 were shown in up to 80% of the PTC cases, whereas the other thyroid diseases studied showed little or no cellular deposition. Nonneoplastic tissue of PTC-containing thyroid glands (n = 22) lacked staining for IgG in 50% of the cases, and 82% were devoid of complement. The results suggest a tumor-specific immune response in PTC with activation of the classical complement cascade.

Adolescent↗