Induction of IgA against Haemophilus parainfluenzae Antigens in Tonsillar Mononuclear Cells from Patients with IgA Nephropathy

Much evidence suggests that IgA production in vivo and in vitro is enhanced in patients with IgA nephropathy (IgAN). We have demonstrated glomerular deposition of the outer membranes of Haemophilus parainfluenzae (HP) antigens (OMHP) and the presence of HP-specific IgA in the serum of patients with IgAN. In this study, we investigated the production of IgA and several cytokines by tonsillar mononuclear cells (TMC) from IgAN patients induced by stimulation with OMHP. The spontaneous production of total IgA and TGF-β by TMC from IgAN patients was higher than that by TMC from patients with chronic tonsillitis (CT) (P < 0.05). Stimulation with OMHP in vitro enhanced the production of HP-specific IgA by TMC from IgAN patients (P < 0.01), but not by TMC from CT patients. OMHP stimulation also enhanced the production of TGF-β and IL-10 by TMC from IgAN patients (P < 0.001). These results suggest that the infection of HP in the tonsil may be involved in the etiology of IgAN.     

Intestinal, Salivary, and Tonsillar IgA and J-Chain Production in a Patient with Severe Deficiency of Serum IgA

An 18-year-old man with tendency to respiratory infections had a serum IgA level of only 2% of normal whereas his salivary IgA amounted to 50% of the lower normal concentration range. Moreover, both the rectal and jejunal IgA-producing cell populations were of normal size. Nevertheless, a relative increase of salivary IgM and a distinctly raised number of IgM-producing cells in jejunal mucosa indicated an imbalance in his secretory immune system. This possibility was supported by the presence of an excess of J 3 chains in most of his intestinal IgA immunocytes, probably reflecting a reduced synthetic rate of IgA. The number of tonsillar IgA-producing cells was only slightly below the normal range; most of them lacked J chain, as normal, and could thus be a source of his serum IgA, which was mainly monomeric. A marked deficiency of IgA-producing cells in his bone marrow supported the notion that this tissue site normally is the major source of monomeric IgA. This study suggests that a generally defective IgA system may be topically activated owing to the persistent antigenic and mitogenic load on mucosa-associated lymphoid tissues. Our findings are not consistent with a general regulative compartmentalization of monomer- and dimer-producing IgA immunocyte populations.     

Affinity Purification of IgG Subclasses and the Distribution of Thyroid Auto-Antibody Reactivity in Hashimoto''s Thyroiditis

To delineate accurately the IgG subclass distribution of thyroid auto-antibodies, sera from nine patients with Hashimoto's thyroiditis were fractionated into IgG subclasses by complete depletion of the other IgG subclasses on affinity columns. All IgG subclass fractions contained thyroglobulin and microsomal (or thyroid peroxidase) antibody activity, although when compared to the total serum concentrations of IgG subclasses, IgG4 antibodies were overrepresented. However, in contrast to recent studies, this particular subclass never predominated--IgG4 antibody levels being exceeded by those of the IgG1 and IgG2 subclasses; it seems likely that these differences relate to varying sensitivity for different subclasses in previously used assay methods. This pattern of subclass activity differed from that of tetanus toxoid antibodies, which were found in six subjects. There was no light chain restriction within any subclass, showing that the overproduction of IgG4 thyroid antibodies is not of monoclonal origin. The functional affinity of subclasses for both thyroid antigens varied between patients, but IgG2 subclass fractions showed the highest functional affinity in the majority of samples. We also found that IgG2 subclass thyroid antibodies were ineffective in eliciting antibody-dependent cell-mediated cytotoxicity, as distinct from the other three subclasses. Our results show that thyroid antibodies are less restricted in their IgG subclass distribution and patients are less heterogeneous than previously described. Moreover, IgG2 thyroid antibodies are quantitatively important and differ in relative functional affinity and effector function from IgG1 and IgG4 thyroid antibodies.     

Self-aggregated deglycosylated IgA1 with or without IgG were associated with the development of IgA nephropathy

IgA nephropathy (IgAN) is the most common primary glomerulonephritis, with various pathological phenotypes. Our previous study suggested that aberrant glycosylation of serum IgA1 was associated with different pathological phenotypes of IgAN, and substantial evidence indicated that deglycosylated IgA1 had an increased tendency to form macromolecules. The aim of the current study was to investigate the composition of IgA1-containing macromolecules in different pathological phenotypes of IgAN. Sera from 10 patients with mild mesangial proliferative IgAN (mIgAN), 10 with focal proliferative sclerosing IgAN (psIgAN) and 10 healthy blood donors were collected. The sera were applied and IgA1 binding proteins (IgA1-BP) were eluted from the columns immobilized with desialylated IgA1 (DesIgA1/Sepharose) or desialylated/degalactosylated IgA1 (DesDeGalIgA1/Sepharose), respectively. The amounts of IgA1 and IgG and the glycoform of IgA1 in the IgA1-BP were detected by enzyme-linked immunosorbent assays (ELISAs) and were compared between patients with different pathological phenotypes and normal controls. The amount of IgA1 in IgA1-BP eluted from both columns was significantly higher in patients with both pathological phenotypes of IgAN than in normal controls. In IgA1-BP eluted from DesDeGalIgA1/Sepharose, the desialylation of IgA1 was much more pronounced in patients with both pathological phenotypes of IgAN than in normal controls, while the degalactosylation of IgA1 was much more pronounced only in patients with psIgAN than in normal controls. Furthermore, the amount of IgG in IgA1-BP eluted from DesDeGalIgA1/Sepharose was significantly higher in patients with psIgAN than in normal controls. In patients with psIgAN, the amount of IgG eluted from DesDeGalIgA1/Sepharose was much greater than from DesIgA1/Sepharose. In conclusion, self-aggregated deglycosylated IgA1 with or without IgG were associated with the development of IgAN.     

IgA肾病患者全基因组miRNA表达谱的特征及其染色体分布

目的:调查研究IgA肾病(IgA-N)患者全基因组miRNA的表达及其编码基因的染色体分布特征.方法:运用Illumina高通量测序技术分别对6例IgA-N患者肾活检组织和6例肾癌患者癌旁正常组织的全基因组miRNA表达水平进行检测,比较分析两组miRNA的表达差异,并对其编码基因的染色体分布情况进行分析.结果:在两组样本中共检测到370种具有显著性差异表达的miRNA,共同表达的miRNA有249种(在IgA-N组中53种表达上调,196种表达下调),另外还有4种和117种miRNA分别特异性表达于IgA-N组和对照组.两组样本miRNA基因表达的染色体分布趋于一致,染色体1、7、9、14、17和X对疾病的贡献值较高.结论:IgA-N患者肾脏组织具有特定的miRNA表达谱和染色体分布特征.染色体7、17、X可能在IgA1糖基化异常过程中起重要作用.     

Impaired lung function in patients with IgA deficiency and low levels of IgG2 or IgG3

We examined the relation between serum levels of IgG subclasses and lung function, as determined by spirometry, lung volumes, the single-breath nitrogen test, and static recoil pressures, in 29 patients with IgA deficiency and repeated upper or lower respiratory tract infections. Four of the patients had decreased levels of IgG2, and two had decreased levels of IgG3. Two or more lung-function values were abnormal in each of these six patients and also in three others with normal levels of IgG subclasses. Low levels of IgG2 and IgG3 were significantly related to abnormal lung function (P less than 0.01). The 20 patients with normal lung function all had IgG-subclass levels above the lower range. There may be a causal relation between low levels of IgG subclasses and deterioration in lung function, suggesting that patients with combined IgA and IgG-subclass deficiencies may benefit from immunoglobulin prophylaxis.     

Subclass Distribution of IgA and IgG Antibodies Against Clq in Patients with Rheumatic Diseases

To obtain insight into the immunoregulatory mechanisms in patients with different rheumatic diseases, the occurrence and the subclass distribution of IgA and IgG antibodies against Clq (anti-ClqAb) was determined. In patients with systemic lupus erythaematosus (SLE) the highest frequency of increased serum levels of IgG anti-ClqAb were found, whereas IgA anti-ClqAb were predominantly present in patients with ankylosing spondylitis (AS) and patients with rheumatoid arthritis complicated by vasculitis (RV). In all the IgA anti-ClqAb positive AS and RV patients the antibody reactivity involved the IgAl subclass while the IgA2 subclass was found in 47% of the patients. Further characterization of the IgA anti-Clq binding activity in sera of AS patients revealed that both subclasses of IgA anti-ClqAb were predominantly polymeric; the binding of both IgA subclasses with solid phase CI q was inhibitable by aggregated fluid phase Clq; we found no delectable interference of rheumatoid factor in the test system for the measurement of IgA anti-ClqAb. In patients with SLE the IgG anti-ClqAb reactivity was mainly of the IgG2 and IgG3 subclass, whereas in the same patients the IgG anti-tetanus toxoid response was not restricted to these subclasses.
The predominance of IgG2 and IgG3 subclass of anti-ClqAb in sera of SLE patients, suggests a skewing of the anti-ClqAb response. The observation that the IgA anti-ClqAb of both subclasses is predominantly polymeric in nature and the notion that polymeric IgA is associated with activation of inflammation cascades, suggests that IgA anti-ClqAb may contribute to tissue damage.     

Distribution of Ig Classes and IgG Subclasses among Human B Cells Activated by Nocardia opaca-Delipidated Cell Mitogen or by Pokeweed Mitogen

The relative proportions of cells synthesizing the three major Ig classes or one of the four IgG subclasses in cultures stimulated with pokeweed mitogen (PWM) or Nocardia-delipidated cell mitogen (NDCM) were investigated. In cultures of human peripheral blood mononuclear cells (PB MNC) stimulated with PWM, the number of IgG-containing cells (CC) was higher than the number of IgM-CC, and a substantial number of IgA-CC was found. Conversely, in NDCM-stimulated PB MNC cultures IgM-CC outnumbered IgG-CC and only few IgA-CC were detected. In those cultures, the removal of T cells resulted in an increase in the number of IgM-CC concomitant with a decrease in the number of IgG-CC. A substantial number of cells containing simultaneously IgG or IgA in addition to IgM could be found in PWM-stimulated cultures. These cells were virtually absent in NDCM-stimulated cultures. The relative proportions of IgG subclass-CC were IgG1-CC greater than IgG2-CC greater than IgG3-CC greater than or equal to IgG4-CC in PWM-stimulated and IgG2-CC greater than IgG1-CC greater than IgG3-CC greater than or equal to IgG4-CC in NDCM-stimulated cultures. The removal of T cells from NDCM-stimulated cultures did not result in major alteration of this distribution. The role of T cells and of the genomic order of the Igh-C genes in their phenotypic expression triggered in vitro by PBA is discussed.     

Influence of Tonsillar Disease on the Expression of J Chain by Immunoglobulin-producing Cells in Human Palatine and Nasopharyngeal Tonsils

A significant reduction of the percentage of J-chain-positive intra- and extra-follicular IgA immunocytes was found in inflamed palatine tonsils. There was a tendency to similar alterations in hypertrophied adenoids. Tonsillar disease apparently enhances local maturation of the B-cell system, perhaps on the basis of intensified proliferation of memory clones. Alternatively, there may be a disease-associated defect in the mechanism(s) that normally induces switchover to the IgA isotype early in clonal development. It is speculated that, by decreasing the J-chain expression during local B-cell differentiation, tonsillar disease may jeopardize the potential of the tonsils as a putative precursor source for the secretory immune system of the upper aero-digestive tract.     

Validation study of Oxford Classification of IgA Nephropathy: the significance of extracapillary hypercellularity and mesangial IgG immunostaining

The Oxford classification (OC) of IgA Nephropathy (IgAN) identified mesangial hypercellularity (M), endocapillary hypercellularity (E), segmental glomerulosclerosis (S), and tubular atrophy/interstitial fibrosis (T) as predictors of outcome. We aimed to validate the OC and to investigate the clinical significance of extracapillary hypercellularity and IgG immunostaining. We examined the renal outcome at December 31, 2014, of 121 adult patients with biopsy proven primary IgAN between 2003 and 2013. The primary endpoint was doubling of serum creatinine or renal replacement therapy initiation. The mean observation period was 59.7 months. Thirty‐one percent of the patients presented with a grade of extracapillary hypercellularity. In comparison with the group with no crescents, they had higher grade of inflammation, lower eGFR and increased proteinuria. There were no differences between the IgA and IgA&IgG immunostaining groups regarding the disease progression risk factors. Mean kidney survival time for the entire cohort was 10.6 (9.1, 12.0) years. In the Cox regression model, the independent predictors of decreased renal survival were eGFR at time of biopsy, S1 and the presence of crescents. Our study showed that extracapillary proliferation and S1 had the greatest importance in establishing the renal prognosis of patients with IgAN.     

Distribution of Surface, Cytoplasmic and Secreted IgG Subclasses in Human Lymphoblastoid Cell Lines and Normal Peripheral Blood Lymphocytes

Twenty-two IgG-positive human lymphoblastoid cell lines and normal peripheral blood lymphocytes were studied for surface and cytoplasmic IgG, IgG subclasses, IgD and IgM, using monospecific fluorescein-and rhodamine-conjugated F(ab')₂ antibody fragments, and for secretion by double antibody radioimmunoassay. Several parallel observations and several differences in IgG subclass expression were noted between cell lines and normal lymphocytes. Surface IgG2 was frequently expressed in normal IgG-positive lymphocytes but was seldom expressed in cell lines. Cell lines resembled normal IgG-positive lymphocytes in the frequent expression of cytoplasmic IgG3 and lgG4, often without secretion. Cell lines and normal lymphocytes both showed more frequent distribution of IgG and IgG sub-classes in cytoplasm than in surface immunoglobulin, and often a discrepancy of surface versus cytoplasmic IgG subclass. A good correlation was noted between surface, cytoplasmic and secreted IgG1. Despite a predominance of IgG2 and IgG4 surface IgG subclasses, and IgG3 and IgG1 in cytoplasm, secreted immunoglobulins from normal lymphocytes in short-term culture showed a similar distribution of IgG subclasses to that seen in normal sera. Multiple expression of IgG subclasses was much more frequent in IgG-positive cell lines than in normal peripheral blood lymphocytes, both in surface and cytoplasmic IgG.     

Expression of MicroRNAs in the Urinary Sediment of Patients with IgA Nephropathy

Background: Micro-RNAs (miRNAs) regulate one-third of all protein-coding genes and are fundamental in the pathophysiology of a wide range of diseases. We studied the expression of several miRNA species (miR-200 family, miR-205 and miR-192) in the urinary sediment of patients with IgA nephropathy (IgAN). Methods: We studied 43 patients with biopsy-proven IgAN. Urinary expression of miRNAs was determined and compared to that from 13 healthy controls. Results: The levels of urinary miR-200a, miR-200b and miR-429, but not miR-200c, miR-141, miR-205, or miR-192, were down-regulated in patients with IgAN. Proteinuria significantly correlated with urinary expression of miR-200a (r = −0.483, P < 0.001), miR-200b (r = −0.448, P = 0.001) and miR-429 (r = −0.466, P = 0.001). Baseline renal function significantly correlated with urinary expression of miR-200b (r = 0.512, P < 0.001) and miR-429 (r = 0.425, P = 0.005). Urinary gene expression of ZEB2 inversely correlated with miR-200b (r = −0.321, P = 0.017); and vimentin expression inversely correlated with that of miR-200a (r = −0.360, P = 0.007), miR-200b (r = −0.416, P = 0.002) and miR-429 (r = −0.375, P = 0.005). After 33.4 ± 12.6 months, the rate of renal function decline significantly correlated with urinary expression of miR-200b (r = 0.316, P = 0.034). Conclusions: Urinary expression of miR-200a, miR-200b and miR-429 were down-regulated in patients with IgAN, and the degree of reduction correlated with disease severity and rate of progression. The results suggested that these miRNA species might play important roles in the pathophysiology of IgAN. Further studies are needed to clarify the role of urinary miRNA repression as a non-invasive marker of IgAN.     

Distribution of IgM, IgA and IgG secreting cells in the tissues of normal and tumour-bearing mice.

The levels of IgM, IgA and IgG secreting cells were examined in control, Corynebacterium parvum-stimulated and tumour-bearing, normal and athymic (Nu/Nu) mice. The percentage of IgA to IgM or IgG secreting cells is relatively higher in peripheral blood than in the spleen or peritoneum of normal mice. Within tumours, irrespective of their degree of vascularization and immunogenicity, the pattern of Ig secreting cells in similar to that seen in peripheral blood and different from that in spleen and peritoneum even in athymic mice. Intraperitoneal injection of C. parvum changes the relative percentages of Ig secreting cells in the peritoneal cavity to resemble that seen in the peripheral blood and tumours. It appears that Ig secreting cells extravasate from peripheral blood in a non-isotype specific manner into sites of chronic stimulation.     

Severity of infections in IgA deficiency: correlation with decreased serum antibodies to pneumococcal polysaccharides and decreased serum IgG2 and/or IgG4

In order to define abnormalities of humoral immunity which determine susceptibility to respiratory tract infections in IgA-deficient adults, serum IgG subclass concentrations, and serum concentrations of pneumococcal antibodies and Haemophilus influenzae type B (Hib) antibodies sera from IgA-deficient adults with and without susceptibility to respiratory tract infections were compared. Infection susceptibility was not related to the degree of IgA deficiency, but was related to deficiency of IgG4 and, to a lesser extent, IgG2, as well as to low basal serum concentrations of pneumococcal polysaccharide antibodies. The combination of IgG2 and/or IgG4 deficiency and a non-protective basal serum concentration of antibody against two or more pneumococcal polysaccharides was present in the serum of six of 12 (50%) patients with severe infections, but only one of 44 (2%) patients without infections. Furthermore, the preservation of antibody responses against the most immunogenic pneumococcal polysaccharide type 3, but not against the less immunogenic types 7F, 9N and 14, in patients with severe infections suggested that abnormalities of pneumococcal polysaccharide antibody responses might include defects of affinity maturation.     

Kinetics of Thymidine Entry Into Tonsillar Lymphocytes and Its Alteration in the Presence of a Lymphokine

Thymidine uptake into the acid soluble cell fraction of human tonsillar lymphocytes was studied in vitro. Uptake was linear for 15–20 minutes at low concentrations (<1.2 μM) of thymidine. The plot of uptake versus time could be extrapolated to the origin. Value for K_M (0.5–0.6 μM) and values for V_max were determined.

In the presence of a lymphokine which inhibited thymidine incorporation into DNA the uptake of thymidine into the acid soluble cell fraction was also inhibited. The decreased uptake could be characterized by an increase in the apparent K_M, without the alteration of V_max.

Lymphokines which inhibit thymidine incorporation may influence and regulate in vivo the entry of the exogenous thymidine into the cells.     

Immunological abnormalities in the tonsils of patients with IgA nephropathy: inversion in the ratio of IgA: IgG bearing lymphocytes and increased polymeric IgA synthesis

In the last few years the mucosal origin of the IgA deposited in the kidneys of patients with IgA nephropathy has been examined by several investigators. We have previously presented evidence that polymeric IgA may have a predominant role in the pathogenesis of IgA nephropathy. Taking into account that these patients often present with macroscopic haematuria following respiratory tract infections we have studied the possible existence of immunological abnormalities in the tonsils of patients with IgA nephropathy. Six patients and 13 controls suffering from chronic tonsillitis were submitted to tonsillectomy. Patients with IgA nephropathy showed a significant increase (P less than 0.00025) in IgA bearing lymphocytes (14.4 +/- 2.3) and a significant decrease (P less than 0.025) in IgG bearing lymphocytes (20.5 +/- 4.6) compared to the control group (2.9 +/- 1.4 and 31.6 +/- 3.6, respectively). After 7 days of culture with pokeweed mitogen the percentage of tonsillar cells producing polymeric IgA was significantly higher in the patients than in the controls (66.5 +/- 12.6 vs 33.4 +/- 10.3; P less than 0.005). These results also suggest a mucosal origin for the IgA deposited in the kidneys of these patients. Our data are consistent with the existence of an immunoregulatory dysfunction in the secretory immune system of patients with IgA nephropathy.     

血清IgA、C3及IgA/C3比值在IgA肾病诊断中的应用价值

目的：探讨原发性IgAN和非IgAN原发性肾小球肾炎患者血清IgA、C3水平和IgA/C3比值的差异及与病理Lee氏分级的相关性。方法：选择上海交通大学医学院附属新华医院肾脏内科经肾穿刺组织活检确诊为原发性IgAN患者167例与非IgAN原发性肾小球肾炎患者105例,以透射免疫比浊法测定其血清IgA和C3浓度,按Lee氏分级标准评估IgAN的病理分级。结果：①原发性IgAN患者与非IgAN原发性肾小球肾炎患者血清IgA水平分别为[（2.98±1.27）vs（2.15±0.88）g/L,P〈0.01];血清C3水平分别为[（1.11±0.27）vs（1.12±0.29）g/L,P〉0.05];IgA/C3比值分别为[（2.83±1.34）vs（2.05±1.12）,P〈0.01];②Lee氏分级为Ⅰ和Ⅱ级与Lee氏分级为Ⅲ、Ⅳ、Ⅴ级的IgAN患者血清IgA水平分别为[（2.73±0.95）vs（3.12±1.41）g/L,P〈0.05];血清C3水平分别为[（1.94±0.32）vs（1.10±0.24）g/L,P〉0.05];IgA/C3比值分别为[（2.70±1.45）vs（2.90±1.26）,P〉0.05]。③IgAN患者不同临床起病表现组间IgA、C3水平和IgA/C3比值的差异均无统计学意义。结论：血清IgA水平及IgA/C3比值可作为鉴别IgAN与非IgAN的参考指标,血清C3水平的降低程度与IgAN患者病理严重程度相关。     

纤维连接蛋白及其受体在IgA肾病患者肾组织中的表达

为探讨纤维连接蛋白（ＦＮ）及其受体（ＦＮＲ）与ＩｇＡ肾病的关系，利用免疫组织化学和计算机图像分析的方法对４１例ＩｇＡ肾病患者和６例正常人肾组织中的纤维连接蛋白及其受体进行定量研究。结果表明，正常肾组织肾小球ＦＮ分布于系膜区，ＦＮＲ在肾小球系膜区毛细血管袢均有分布Ｉdisplay status     

IgA肾病患者IL—2的产生及IL—2受体的表达

本文对IgA肾病(IgAN)外周血淋巴细胞白细胞介素2(IL-2)的产生、受体的表达及免疫球蛋白的产生进行了研究。结果发现:外周血淋巴细胞产生IL-2的活性明显增高,IL-2受体表达亦明显增强并伴有免疫球蛋白产生增多,提示IgAN存在着细胞免疫功能的紊乱。