C3 degradation products (C3d) in normal pregnancy.

Plasma C3 degradation products (C3d) were measured in 65 normal pregnancies and compared with those of non-pregnant women. No significant difference was detected between the two groups, although a difference had been previously reported. Plasma C3d estimations give an indication of complement activation and may be used as an indicator of disease activity in patients with systemic lupus erythematosus (SLE), irrespective of pregnancy.     

Double-decker rocket immunoelectrophoresis for direct quantitation of complement C3 split products with C3d specificities in plasma

A double-decker rocket immunoelectrophoresis (DD-RIE) method for direct quantitation of complement split products with C3d determinants in human plasma is described. The usefulness of the DD-RIE method for monitoring C3 activation has been assessed and compared with conventional crossed immunoelectrophoresis (CIE) for C3c determination in a patient with iatrogenic septic shock and patients with rheumatoid arthritis. In contrast with CIE the DD-RIE method is quantitative by reference to a standard curve based on an internal reference C3d preparation and its sensitivity and assay capacity are superior to CIE. All reagents and antibody preparation are commercially available and the production of standards is easy. No overlapping was observed between C3d values in plasma from healthy persons and patients with active classical rheumatoid arthritis. The DD-RIE is highly suitable for routine use in laboratories of clinical immunology.     

Activation of classical pathway complement in chronic inflammation. Elevated levels of circulating C3d and C4d split products in rheumatoid arthritis and Crohn's disease

Split products of complement component 3 (C3) and complement component 4 (C4) derived from activation of the alternative and classical complement pathways were measured in untreated outpatients, 20 with Crohn's disease and 19 with rheumatoid arthritis. Elevated levels of the d split product of C4 (C4d) were observed in 12 of 19 patients with rheumatoid arthritis and in 9 of 20 patients with Crohn's disease. Levels of the d split product of C3 (C3d) were increased in 14 of 19 patients with rheumatoid arthritis and in 6 of 20 Crohn's disease patients. The median values of C4d and C3d were significantly increased in both groups of patients. C3d concentrations correlated positively with C4d levels (rs = 0.51-0.56, p less than 0.005). The complement activation was not reflected in reduced plasma levels of native C3 and C4. The data indicate activation of the classical complement pathway in both rheumatoid arthritis and Crohn's disease.     

Pattern of C3, iC3b, and C3d in patients hospitalized for acute asthma.

Twenty-three patients hospitalized for acute asthma were studied for a peripheral blood complement profile consisting of C3, C4, C3d, iC3b, C4d, and Bb concentrations. Compared with normals (n = 22) and patients (n = 10) with acute bacterial infections (ABI), asthmatic patients had significantly higher serum C3 concentrations (P less than .001). Plasma C3d levels and iC3b in asthmatic patients were both comparable to those observed in normal controls, whereas patients with ABI had significantly higher iC3b levels than both other groups. The ratio of iC3b to C3 concentrations were similar in asthmatic patients and controls, and iC3b levels were correlated with total serum C3 levels in asthmatic patients (r = .55, p less than .001) as well as in normal (r = .69, p less than .001). Both of these groups had significantly lower iC3b to C3 ratios compared with the ABI group (P less than .0001). Also observed in asthmatic patients were a significant correlation between serum C4 and C3 levels (r = .83, P less than .001) and a lower mean ratio of plasma C4d to C4 compared with normals (P less than .005). This profile of complement alterations is distinct from that observed in acute bacterial infection. These changes in asthmatic patients may relate to an acute phase reaction phenomenon affecting complement and/or complement regulatory proteins.     

Influence of time,temperature and coagulation on the measurement of C3, C3 split products and C4

Quantitative and qualitative immunoelectrophoretic analyses of circulating C3, C3 split products and C4 were performed in matched EDTA plasma and serum obtained from 5 normal subjects and stored for up to 48 h at room temperature (18°C–22°C) and 4°C. Fluctuations in apparent levels of C3 were greater in serum than plasma stored at room temperature, a fall in levels seen by 24 h being followed by a significant increase. By contrast, levels of C3 did not alter if stored at 4°C. C4 levels in both EDTA plasma and serum remained unchanged for 24 h, a slight decrease being seen at 48 h. Levels of C4 remained constant if samples were stored at 4°C. Crossed immunoelectrophoresis revealed a significant progressive decrease in C3 levels and a simultaneous increase in C3c occuring after 4 h in serum and 8 h in EDTA plasma, stored at room temperature. In studies conducted at 4°C, similar but delayed fluctuations were seen. A progressive and significant increase in C3d levels was seen in both plasma and serum samples stored at room temperature, levels rising to 276% (plasma) and 308% (serum) of levels seen at zero time. At 4°C marginal increases in C3d levels only were observed. These results suggests that in vitro degradation of C3 and C4 are readily facilitated by temperature, time and coagulation, and that conditions of collection and storage of samples must be optimized for the accurate definition of activation of the complement cascade.     

Circulating C3, C4, and C3 Split Products (C3c and C3d) During Normal Pregnancy*

ABSTRACT: The plasma concentrations of the complement components C3 and C4, as well as the split products C3c and C3d, were measured before, during, and after normal pregnancy. Significantly increased values were observed in the C3 and C3d levels in the second and third trimesters of pregnancy. The level of C4 was not significantly affected by pregnancy and C3c could not be detected using electroimmunoassays. These results suggest that the increased C3 split-product levels observed reflected an increased turnover of native C3 rather than activation of the complement cascade.     

A comparative evaluation of receptor reactivities for C3b, iC3b, and C3d on Raji lymphoblastoid cells

Raji cells were described to carry receptors for iC3b, C3d, C3b-beta 1 H and beta 1 H. Controversial opinions, however, exist whether or not these cells carry also receptors for C3b. Using highly purified C3, definitely devoid of beta 1 H and C5, for preparation of C3b intermediates, it could be shown that Raji cells bound to C3b cells. Furthermore, Raji cells reacted with monoclonal antibodies that interfered with binding of C3b to human erythrocytes, lymphocytes and renal cells. The receptor for C3b on Raji cell, however, exhibited some special properties and, therefore, required some distinct experimental conditions for its detection: (1) The origin of the erythrocytes used for preparation of the C3b intermediates seemed to be important; this was not the case when iC3b and C3d receptor reactivity was assessed. (2) Rosettes already formed between Raji cells and EAC1423b showed the tendency to disintegrate within the first 30 min after the rosette formation assay. Again, this effect could not be observed with iC3b- and C3d-dependent rosette formation. (3) Incubation of the Raji cells at 37 degrees C as well as 4 degrees C before rosette formation resulted in a rhythmic loss and reappearance of C3b receptor reactivity. At room temperature (19-22 degrees C) this effect was much less expressed. There was no influence of preincubation at 4 and 37 degrees C, respectively, on the iC3b and C3d receptor reactivity of Raji cells. (4) Diisopropylfluorophosphate (DFP) present during rosette formation enhanced, within a certain range of concentration, the percentage of C3b-dependent rosette formation. iC3b and C3d receptor reactivity was not influenced. A similar reaction pattern was observed with pokeweed mitogen (PWM)-stimulated tonsil lymphocytes. In the concentrations tested, DFP showed no effect on the rosette formation between C3b, iC3b, and C3d cells, respectively, and unstimulated tonsil lymphocytes. The data presented suggest that C3b receptors on Raji cells undergo some special metabolism, possibly controlled by fluid phase or cell-bound proteases. This might be a common property of C3b receptors on blast-like and transformed cells, differing from that of unstimulated small lymphocytes.     

小鼠补体C3d分子cDNA的克隆及鉴定

目的 获得小鼠C3d分子的cDNA。方法 从小鼠肝细胞提取总RNA，通过RT—PCR扩增出C3d分子的cDNA，琼脂糖凝胶电泳鉴定后直接克隆到pMD18—T载体，构建C3d—pMD18—T重组质粒，转化大肠杆菌，酶切鉴定后进行序列测定。结果 通过琼脂糖凝胶电泳证明有1．0kb左右的PCR扩增片段，序列测定表明为C3d分子的cDNA。结论 通过RT—PCR法从小鼠肝细胞RNA中成功地扩增到小鼠C3d分子的cDNA，为进一步构建基于C3d分子内佐剂的疫苗奠定了基础。     

C3d及荷C3d免疫复合物的测定与意义

用抗人Ｃ３和抗人ＩｇＧγ球蛋白组分作固相反应物，建立了检测补体活化片段Ｃ３ｄ及荷Ｃ３ｄ－ＩＣ的ＥＬＩＳＡ法，并对临床各类疾病患者血清Ｃ３ｄ和Ｃ３ｄ－ＩＣ的水平进行了测定，结果表明：慢性肾炎，ＳＬＥ，慢性乙肝及肺炎患者血清Ｃ３ｄ总体水平均较对照组显著增高，分别有５８．５％～７２．２％的病人Ｃ３ｄ含量高于正常上限（Ｐ〈０．０１），且该类病人亦有较高的Ｃ３ｄ－ＩＣ阳性检出率（肺炎患者例外）本项研究中，Ｃ     

草原兔尾鼠卵透明带3DNA疫苗pVAX1-sig-LTB-lZP3-C3d3的构建表达及其免疫不育的研究

目的:构建草原兔尾鼠卵透明带3 DNA疫苗pVAX1-sig-LTB-lZP3-C3d3进行小鼠的黏膜免疫,增强该疫苗的免疫不育效果。方法:将两种佐剂分子大肠杆菌不耐热肠毒素B亚基和C3d基因通过酶切鉴定,构建重组质粒pVAX1-sig-LTB-lZP3-C3d3,采用RT-PCR和W estern b lot技术,检测其在mRNA和蛋白水平的表达,并通过肌肉注射、滴鼻和灌服3种途径免疫雌性C57BL/6小鼠,通过ELISA检测抗体水平及分型。结果:酶切鉴定,RT-PCR和W estern b lot结果表明重组质粒构建正确并可在mRNA和蛋白水平的表达,ELISA结果表明以重组质粒pVAX1-sig-LTB-lZP3-C3d3免疫诱导的特异性IgG、IgA的水平明显高于对照组(P<0.01)。抗生育实验表明该疫苗免疫的小鼠平均生仔数与对照组相比差异极显著(P<0.01)。结论:构建的草原兔尾鼠卵透明带3DNA疫苗重组质粒pVAX1-sig-LTB-lZP3-C3d3可高效地激发小鼠特异性免疫应答,提高抗生育的效果。     

草原兔尾鼠卵透明带3DNA疫苗pVAX1-sig-LTB-IZP3-C3d3的构建表达及其免疫不育的研究

目的:构建草原兔尾鼠卵透明带3 DNA疫苗pVAX1-sig-LTB-IZP3-C3d3进行小鼠的黏膜免疫,增强该疫苗的免疫不育效果.方法:将两种佐剂分子大肠杆菌不耐热肠毒素B亚基和C3d基因通过酶切鉴定,构建重组质粒pVAX1-sig-LTB-IZP3-C3 d3,采用RT-PCR和Western blot技术,检测其在mRNA和蛋白水平的表达,并通过肌肉注射、滴鼻和灌服3种途径免疫雌性C57BL/6小鼠,通过ELISA检测抗体水平及分型.结果:酶切鉴定,RT-PCR和Western blot 结果表明重组质粒构建正确并可在mRNA和蛋白水平的表达,ELISA结果表明以重组质粒pVAX1-sig-LTB-IZP3-C3d3免疫诱导的特异性IgG、IgA的水平明显高于对照组(P＜0.01)o抗生育实验表明该疫苗免疫的小鼠平均生仔数与对照组相比差异极显著(P＜0.01).结论:构建的草原兔尾鼠卵透明带3DNA疫苗重组质粒pVAX1-sig-LTB-IZP3-C3d3可高效地激发小鼠特异性免疫应答,提高抗生育的效果.     

Candida albicans and Candida stellatoidea, in contrast to other Candida species, bind iC3b and C3d but not C3b.

It was demonstrated that complement-coated sheep erythrocytes bind to Candida albicans cells grown in serum-free RPMI 1640 medium. Testing of purified complement components proved that iC3b and C3d were responsible for the reaction, whereas C3b and C3b-H reacted only slightly if at all. Binding occurred only to C. albicans and C. stellatoidea, not to other species pathogenic to humans. There was evidence of a lectinlike nature of the effect.     

Regulation of Human Cytotoxic Responses by Complement: C3, C3b and C3d Preparations Enhance Human Allogeneic Cytotoxic Responses

Complement components and complement. breakdown products have been found to participate in the regulation of the immune response. In the present study we investigated the effect of C3 and its fragments, C3b, C3c and C3d on human allogeneic cell mediated lympholysis (CML). C3 and C3b at a concentration of 275 M × 10^-9 and C3d at a concentration of 330 M × 10^-9 enhanced human allogeneic CML by at least two fold. In contrast C3C did not affect CML responses. Both C3b and C3d had to be present at the initiation of the cultures in order to exert their effect. Similar doses of C3b and C3d did not affect the mixed lymphocyte responses (3_H-thymidine uptake) while higher doses were clearly inhibitory. None of the preparations induced proliferative or cytotoxic responses in the absence of allogeneic stimulating cells. C3b and C3d added to the mixed lymphocyte cultures caused increased production of interleukin 2. We conclude that C3b and C3d facilitate allogeneic cytotoxic responses through increased production of interleukin 2.     

A new method for the estimation of C3d Affinity clearance of C-determinant-bearing C3 molecules and fragments followed by estimation of C3d by ELISA

A method is described to quantitate human complement fragment C3d. Test samples were treated with a predetermined excess of anti-C3c-Sepharose beads in the presence of EDTA to remove all the C-determinant-bearing C3 molecules or fragments. C3d left in the supernatant was then estimated by ELISA. Using this method, C3d could be estimated accurately in normal plasma samples. A good correlation (r = 0.93) was observed between C3d values obtained by this method and values obtained by the widely used method of Perrin and coworkers. The average C3d plasma concentration was 2.8 mg/l (SD = 0.7 mg/l, N = 21). The interassay coefficient of variation using a normal plasma pool (C3d 2.7 mg/l) was 8.3% and using normal plasma pools in which the C3d concentrations were raised to 10.3 and 17.4 mg/l by the addition of aged normal serum the levels were 8.0 and 7.5% respectively. Intra-assay coefficients of variation with these samples were 4.6, 3.0 and 2.8% respectively. 16 patients with renal dysfunction had C3d levels in the range of 4.3–10.0 mg/l and 15 patients undergoing continued ambulant peritoneal dialysis had levels of 3.3–12.2 mg/l. The C3d content in peritoneal dialysate of patients undergoing dialysis varied from 9.3 to 383 μg/l.