Mutual inhibition of the binding of Clq and protein A to rabbit IgG immune complexes

A complex of rabbit IgG antibody with horseradish peroxidase covalently linked to Sepharose 4B was used as an insoluble immune complex for studying the binding of complement factor C1q protein A from Staphylococcus aureus, and its IgG-binding fragments AB and B, to rabbit IgG. It was shown that protein A (mol. wt approx. 42,000) and fragments AB and B (mol. wts approx. 14,000 and 7000, respectively) inhibited the binding of C1q to insoluble immune complex at 4 degrees C. However, at 37 degrees C fragment B did not inhibit this binding. On the other hand, C1q, when bound to an insoluble immune complex, almost completely blocked the binding of protein A and fragment B at both temps. The higher affinity of C1q for its CH2-binding site than of fragment B for its CH2-binding site may explain the displacement of the latter from the CH2 domain. The mutual inhibition of the binding of C1q and protein A (and its smaller fragments) indicates that the binding sites for C1q and protein A are closely located in the CH2 domain.     

Some theoretical considerations regarding the effects of steric hindrance and intrinsic global coupling on the flexibility of Fc-anchored immunoglobulins

Nanosecond fluorescence depolarization studies reported in the accompanying companion paper showed that the long rotational correlation time, phi L, increased somewhat when rabbit IgG anti-dansyl antibodies were anchored in staphylococcal protein A (SpA) soluble complexes. The increases in phi L upon anchoring IgG probably resulted from "global coupling" effects caused by: increased steric hindrance of the antibody segments in the SpA complexes and intrinsic structural constraints already present in the monomeric IgG. Global coupling results from a restriction in the angular range of a flexible segment and is manifest when flexible motions alone cannot depolarize all of the fluorescence, so that the slower global tumbling of the entire particle is also required. Such effects cannot be resolved directly from experimental anisotropy data, however, because only a single long correlation time, phi L, is well defined over the limited time range of most fluorophores. In this paper, estimates of the anisotropy contributions from flexible and global motions of the IgG-SpA complexes are determined by contrasting theoretical and measured decays. For this analysis it was assumed that each of the experimental phi L-values is a weighted composite of the rotational correlation time associated with the less restricted flexible motions of the Fab arms, phi F, and the correlation time associated with global tumbling of the entire particle, phi G. A general two-exponential expression was used to relate phi F and phi G to phi L. This approach was meaningful because phi G-values of the various SpA complexes had been calculated from hydrodynamic measurements. The theoretical decays clearly show that, even if phi G is much longer than phi F, these two rotational motions still cannot be resolved over the experimentally accessible time range. Families of emission anisotropy decay curves for IgG antibodies with different amounts of intrinsic global coupling and for anchored antibodies with different amounts of steric hindrance were simulated by varying the preexponential weighting factors of the flexible and global terms. By comparing the calculated curves with the measured decays, it is evident that the rabbit IgG anti-dansyl antibodies do not have much intrinsic global coupling, but rather they are highly flexible. The curves also indicate that even for the exceptionally compact IgG4-SpA2 17-S complex, which showed the most steric hindrance in electron micrographs, the appropriate phi G weighting factor is only 0.28. Thus, as supposed earlier, the anchored antibodies exhibit considerable segmental flexibility. In closing, the above concepts are used to examine the results of     

依那西普联合来氟米特治疗脊柱关节病的疗效观察

目的观察依那西普联合来氟米特在治疗脊柱关节病(SpA)中的疗效及安全性。方法 21例SpA患者接受依那西普50 mg/周+来氟米特20 mg/d联合治疗,所有入组病人每10 d记录一次疼痛目视模拟测试表(VAS),患者及医生对患者健康状况的总体评估,检测强直性脊柱炎活动指数(BASDAI)和功能指数(BASFI)、C-反应蛋白(CRP)、血沉及血尿常规、肝肾功能及安全性指标。结果 21例入组病人在疼痛目视模拟测试表(VAS),患者及医生对患者健康状况的总体评估,BASDAI、BASFI、C-反应蛋白、血沉,显示出显著改善。安全性方面,注射部位反应6/21(其中1例出现局部结节红斑,直径超过50mm),头痛2/21,上呼吸道感染3/21例,腔隙性脑梗死1/21(因怀疑可能与应用依那西普有关,该例病人在应用1周后退出观察),血液系统改变中有6/21例,出现淋巴细胞的轻度升高,肝功轻度异常4/21例,所有患者均未出现肾功方面的不良反应。结论依那西普联合来氟米特在脊柱关节病治疗中,10周时症状迅速得到控制,无严重的不良反应,并且是安全的。     

Evaluation and Management of the Patient With Suspected Inflammatory Spine Disease

Axial spondyloarthritis (AxSpA) is a chronic inflammatory rheumatic disease characterized by inflammatory back pain (IBP) that manifests in childhood, late adolescence, or early adulthood. Ankylosing spondylitis (AS) and nonradiographic AxSpA represent 2 ends of the AxSpA spectrum. Diagnosis can be challenging because patients develop IBP that may not be associated with radiographic changes in the sacroiliac joints. Patients early in the course of disease are estimated to have at least the same level of disease activity and pain as patients with established disease; thus, they could benefit substantially from earlier diagnosis. Although the recent use of magnetic resonance imaging and its inclusion in diagnostic criteria has enhanced the identification of early AxSpA, improvement in early diagnosis has not been consistently reported across all studies. Limited knowledge of the continuum of AxSpA disease manifestations and lack of recognition of IBP in primary practice may contribute to this. Implementing a referral strategy that identifies patients with IBP for additional testing and assessment may lead to better recognition of early signs and symptoms of AxSpA, thereby offering the potential for improved patient outcomes. This review presents an overview of the epidemiology, clinical characteristics, and burdens of AxSpA, followed by a case presentation outlining approaches to the evaluation and management of a patient with suspected inflammatory spine disease.     

The inhibition capacity of concanavalin a on monomeric and polymeric hemolytic antibodies

The ability of concanavalin A (Con A) to inhibit the complement consumption by sheep erythrocytes coated with IgG, (IgG₂-SpA₁)₂ complex and IgM anti-Forssman antibodies was studied. The (IgG₂-SpA₁)₂ anti-Forssman antibody complex showed an increased hemolytic activity compared to uncomplexed IgG antibody. Con A in the presence of the (IgG₂-SpA₁)₂ complex or the IgM antibody exhibited a high inhibitory capacity. An inhibitory capacity of Con A on IgG antibody hemolytic activity was also proved but at a Con A: IgG antibody concn ratio about 10 times higher than that for the Con A-IgM antibody system. A time dependence of Con A inhibitory capacity was determined, thus explaining the variable behaviour of the IgG antibody in the inhibition experiments. Radioactivity experiments demonstrated that only half of the Con A interacted with the (IgG₂-SpA₁)₂ complex compared to the amount of Con A which interacted with IgG uncomplexed antibody.     

血清阴性脊柱关节病患者血清软骨寡聚基质蛋白水平及意义的研究

目的探讨检测软骨寡聚基质蛋白(COMP)水平对血清阴性脊柱关节病(SpA)患者疾病活动性及早期软骨破坏的临床意义。方法采用酶联免疫吸附试验(ELISA)方法,检测40例SpA患者及40例正常人血清中COMP的水平。同时测定SpA患者的其他实验室及临床指标:类风湿因(RF)、血沉(ESR)、C-反应蛋白(CRP)、肿痛关节数、附着点压痛数、夜间背痛(h)、骶髂关节压痛、脊柱活动度(Schober试验)及骶髂关节的CT分级,分析它们与COMP的相关性。结果SpA患者血清COMP水平(11.459±3.091)U/L明显高于正常对照组(9.234±1.722)U/L,两组差异有统计学意义(P<0.001)。28例SpA活动期患者血清COMP水平为(12.772±2.223)U/L,与12例不活动期患者[(9.450±2.211)U/L]比较差异有非常显著性意义(P<0.001)。COMP水平与SpA患者的ESR、CRP、肿痛关节数、附着点压痛数、夜间背痛(h)、脊柱活动度及骶髂关节的CT分级,呈正相关(P<0.05),与年龄、病程、RF、骶髂关节压痛、无明显相关(P>0.05)。结论SpA患者血清中COMP高水平存在提示SpA疾病活动性和早期关节软骨破坏。     

软骨寡聚基质蛋白在脊柱关节病患者血清中的水平及意义的研究

目的探讨血清软骨寡聚基质蛋白（COMP）水平与脊柱关节病（SpA）患者病情活动及骨破坏的相关性。方法采用酶联免疫吸附试验（ELISA）方法,检测38例SpA患者、18例正常人及10例注射用重组人Ⅱ型肿瘤坏死因子受体一抗体融合蛋白（商品名益赛普）治疗前后SpA患者血清COMP水平、血沉及C反应蛋白,并行骶髂关节CT分级．记录患者BAS、ASDAS评分及夜间脊柱痛视觉评分（VAS）,分析其与COMP的相关性。结果SpA患者组血清COMP水平为（30．835±8．539）ng／ml,明显高于正常对照组的（12．639±2．939）ng／ml（P〈0．01）;病情活动组血清COMP水平为（34．168±7．988）ng／ml．明显高于非活动组的（25．122±6．243）ng／ml（P=0．01）;治疗后SpA患者血清COMP水平为（17．670±7．199）ng／ml．较治疗前的（35．645±7．381）ng／ml明显下降（P〈0．01）。COMP水平与夜间脊柱痛VAS、ESR、CRP及骶髂关节CT分级正相关．与BSADAI、BSAFI、ASDAS—ESR、ASDAS—CRP正相关,与年龄、病程、BASMI及外周关节受累无显著相关。结论SpA患者血清COMP高水平存在提示病情活动,可能预示明显骨质破坏,血清COMP有可能成为判断SpA疾病活动性和疗效的指标。     

Appropriateness of laboratory tests in the diagnosis of inflammatory rheumatic diseases among patients newly referred to rheumatologists

IntroductionAutoantibody tests are commonly ordered when screening for rheumatic diseases. Rheumatoid factor (RF) and antinuclear antibody (ANA) have low positive predictive values in general practice. Overuse of diagnostic tests can result in an increase in unnecessary referrals, patient anxiety, and further costs.ObjectiveThe objective was to evaluate the utilization patterns, appropriateness, and associated costs of tests including ANA, extractable nuclear antibodies (ENA), anti-double stranded DNA (anti-dsDNA), RF, and HLA-B27 in patients referred to rheumatologists.MethodsA review was conducted of consecutive referrals (accepted and rejected) using university rheumatologists’ practices over one year. Inappropriate investigations, and associated costs were analyzed. Tests were considered appropriate if at least one criterion for a specific disease was provided.ResultsOf 638 referrals the most common reported reasons for referral were: spondyloarthropathies (SpA), rheumatoid arthritis (RA), and lupus (SLE). Prior to referral: 61% had undergone ANA testing at least once, ANA was repeated in one third; 19% had ENA and 21% had anti-dsDNA. 20% had ANA testing with no clinical indication. Half of ENA and anti-dsDNA testing was in the context of a negative ANA. RF was requested in 65% and in close to one third, there was no clinical suspicion of inflammatory arthritis.ConclusionDespite the recommendations by CRA Choosing Wisely Campaign, at least 50% of laboratory investigations, including RF, ANA, ENA, and anti-dsDNA, are inappropriately ordered. More selective ordering of the above tests would lead to marked cost reduction.