Studies on Hanganutziu-Deicher antibodies in renal diseases]

H-D antibodies which were known as antibodies detectable in patients with serum sickness have recently been detected in renal diseases. We attempted to detect IgG, IgA and IgM antibodies to N-glycolyl GM3, among other H-D antibodies, by ELISA in various renal diseases and found increased IgM antibody in mesangial proliferative glomerulonephritis, membranoproliferative glomerulonephritis, IgA nephropathy, minimal change nephrotic syndrome and Henoch-Sch?nlein purpura nephritis (HSPN), elevated IgA antibody in IgA nephropathy and HSPN and raised IgG antibody in IgA nephropathy. In 2 cases of IgA nephropathy, there was noted a good correlation between clinical course and anti-N-glycolyl GM3 antibody titers. Measurement by ELISA of IgG antibody to cytomegalovirus (CMV) seemed as one of immune pathogenetic factors of IgA nephropathy showed a high positive rate for this antibody of IgA nephropathy patients and a positive correlation between the antibody and anti-N-glycolyl GM3 antibody. The key molecule of H-D antigens is N-glycolyl neuraminic acid (NGNA) and this sialic acid does not normally exist in humans. One can surmise, therefore, that in those renal diseases in which there was noted an elevation of anti-N-glycolyl GM3 antibody, this antigen is formed or generated by some unknown mechanism. In other words, it may be that humans are not entirely negative for H-D antigens but have a minimum inherent antigenicity and a potential capacity to synthesize these antigens.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cationic antigens in poststreptococcal glomerulonephritis

Antigen charge is an important factor in the pathogenesis of experimental immune complex glomerulonephritis. Its potential role in man was investigated in post-streptococcal glomerulonephritis, a disease where the causative agent is known. Cationic, extracellular streptococcal antigens were detected in 8 of 18 renal biopsies from patients with acute poststreptococcal glomerulonephritis (APSGN). The antigen was found mainly in earlier biopsies in which both IgG and IgM were present. Patients' sera taken at the time of biopsy contained antibody to cationic, streptococcal antigens. Cationic moieties are known to have affinity for the glomerular basement membrane and it is possible that the type of antigen described here initiates APSGN via in situ immune complex formation.     

Monoclonal antibody analysis of glomerular, tubulo-interstitial infiltrating immune cells in various glomerulonephritis

To investigate the role of cell-mediated immunity (CMI) in glomerulonephritis (GN), we identified the infiltrating immune cells both within the glomerulus and in the interstitium. Frozen sections from 103 patients with various forms of GN: 10 with minor glomerular abnormality (MGA) as control, 10 with minimal change nephrotic syndrome (MCNS), 10 with membranous nephropathy (MN), 9 with focal glomerulosclerosis (FGS), 30 with IgA nephropathy (IgAN), 22 with acute post streptococcal glomerulonephritis (APSGN), and 2 with rapidly progressive glomerulonephritis (RPGN) were examined using monoclonal antibodies (MoAb) by indirect immunoalkaline-phosphatase labelling. In most glomerulonephritis, monocyte/M phi and helper/inducer T cells were predominantly infiltrating in the interstitium, but intraglomerular infiltration was rare, except for APSGN. This interstitial infiltration increased proportionally to the level of serum creatinine, and was most prominent in RPGN. Apparently different distribution was seen in APSGN, that is, prominent increase in total number of intra-glomerular monocyte/M phi infiltration with slightly increased T cells. The change was correlated with time after onset; namely the more leucocytic infiltration was observed when the tissue was taken earlier. These data suggest that in APSGN, monocyte/M phi accumulate in glomeruli via cell mediated immunity in addition to humoral immune mechanism resulting in glomerular hypercellularity, whereas in most chronic glomerulonephritis interstitial leucocyte infiltration, particularly helper T cells and monocyte/M phi may play an important role in the progression of glomerulonephritis.     

Recurrence of acute poststreptococcal glomerulonephritis

Recurrence of acute poststreptococcal glomerulonephritis (APSGN) is a rare phenomenon. We present an 8-year-old boy with a second episode of APSGN 12 months following a complete clinical recovery from his initial attack. Renal histology, obtained from renal biopsies of the patient during the second attack, showed diffuse endocapillary proliferation, granular deposition of C3, IgG, IgA, and fibrinogen along capillary walls, and subepithelial electron-dense deposits. A new streptococcal cytoplasmic antigen (nephritis-associated plasmin receptor protein, NAPlr), which was recently identified as the pathogenic antigen in APSGN, was detected in the glomeruli of an early kidney biopsy specimen from the patient during the second attack of APSGN, using fluorescein isothiocyanate-labeled rabbit anti-NAPlr. However, antibodies against NAPlr, examined by Western blotting, were not present in sera from the patient. These results suggest that recurrence of APSGN in some patients may be caused by an absence of a natural immune response to NAPlr. Received: 7 September 2000 / Revised: 12 February 2001 / Accepted: 13 February 2001     

T cell subset modulation of immunoglobulin production in IgA nephropathy and membranous glomerulonephritis

Monoclonal antibodies directed against T cell subset antigens have been used to deplete peripheral blood human mononuclear cells from helper (OKT4+) and suppressor/cytotoxic (OKT8+) cells. Unfractionated cells and depleted cells were assayed for their capacity to modulate pokeweed mitogen (PWM)-driven IgG, IgA, and IgM production by autologous B lymphocytes. Immunoglobulin production in the presence of these various cell preparations paralleled the OKT4+/OKT8+ ratio defining the population. Importantly, there was no clear relationship between the level of PWM-driven Ig production by unfractionated cells and their initial relative content in OKT4+ and OKT8+ cells. Patients with IgA nephropathy and membranous glomerulonephritis showed a statistically significant increase of OKT4+/OKT8+ ratio, suggestive of suppressor T cell deficiency. There was no increase in IgA production in patients with IgA nephropathy, even in those showing high serum IgA level. A special feature found in patients with IgA nephropathy, irrespective of OKT4+/OKT8+ ratio in unfractionated cells, was a particularly intense enhancement of IgA production after OKT8+ cell depletion in some of the patients, contrasting with a particularly low effect of such depletion on the synthesis of all Ig classes in other patients. In patients with membranous glomerulonephritis there was no obvious abnormality in the modulation of Ig production by T cell subsets, with the exception of a weak suppressor activity with respect only to IgM production in a significant number of patients.     

Streptococcal type-specific antibody in patients with glomerulonephritis (2): Correlation to their histological types

Using the PHA method, streptococcal type-specific antibody was studied in sera from 230 patients with various types of nephritis diagnosed by renal biopsy in order to clarify the relationship between streptococcal infection and the histological types of glomerulonephritis. Two or more serologic types of streptococcal type-specific antibodies with high titers (1:384 or more) were significantly increased in patients with MGA, FGS, PGN, endocapillary proliferative GN, MPGN and IgA GN as compared with those in healthy subjects. Two or more serologic types having high titers (1:384 or more) were significantly increased in MGA, PGN, MPGN and IgA GN as compared with MN. The highest titers (1:768 or more) of streptococcal type-specific antibodies were significantly more frequent in endocapillary proliferative GN as compared with healthy subjects, and such titers were significantly increased in endocapillary proliferative GN and MPGN as compared with MN. The frequency of detection of streptococcal serologic types having high titers (1:384 or more) as found in patients with various nephritis, was in the order of Types 18, 3, 30, 1, 12, 10, 6 and 37, and more than half of the nephritogenic types were included in these serologic types. The above data, which suggest a higher probability of contact with nephritogenic strains during alternative establishment of streptococci by different serologic types, may indicate a close relationship of streptococcal infections with MGA, PGN, MPGN, IgA GN, FGS and endocapillary proliferative GN.     

Anticardiolipin antibodies in acute poststreptococcal glomerulonephritis and streptococcal impetigo.

Anticardiolipin (aCL) antibodies have been described in diverse clinical situations, linked to the risk of thrombosis in different vascular locations. They have been rarely studied in renal diseases, and occasionally they have been associated with glomerular thrombosis. We analyzed the incidence of aCL (isotypes IgG, IgA, and IgM) in samples, taken during the acute phase of the disease, from 27 well-documented patients having acute poststreptococcal glomerulonephritis. Twelve cases were positive on IgG testing, 1 case on IgA testing only, and no one was positive on IgM testing. A serological follow-up was performed with a second sample taken about 7 months later, for the patients initially positive on IgG testing showing persistence in 9. Clinical variables during the acute phase and after a follow-up period of 25 (range 6-89) months were analyzed for possible associations with the presence of these antibodies, but non was significantly related. Renal histopathological investigation did not reveal particular findings in the aCL-positive patients, and glomerular thrombosis was not found in any case. In addition, serum samples from 12 streptococcal impetigo patients without renal involvement were analyzed, showing similar incidence (4 positive on IgG testing, 1 of them positive on IgM testing as well, and no one positive on IgA testing) and titers of aCL antibodies. We conclude that the presence of aCL antibodies in acute poststreptococcal glomerulonephritis may be a marginal immunological phenomenon unrelated to the glomerular disease, triggered by the streptococcal infection.     

Detection of IgG-rheumatoid factor in sera of patients with acute poststreptococcal glomerulonephritis and its relationship with circulating immunecomplexes

Rheumatoid factors (RF) were measured in sera from 75 patients with acute poststreptococcal glomerulonephritis (APSGN) and compared with normal controls, patients with rheumatoid arthritis in activity and acute rheumatic fever. Using two sensitive and specific solid phase radioimmunoassays, IgM-RF and IgG-RF were detected, respectively, in 15% and 32% of the patients with APSGN. A positive correlation (r = 0.37, n = 75, p less than 0.05) was obtained between serum levels of IgG-RF and circulating immune complexes determined by conglutinin assay. Chromatographic studies in serum from two patients with APSGN demonstrated that the circulating IgG-RFs were mainly free, not complexed. It is suggested that RFs, particularly of the IgG class, may participate in the pathogenesis of the renal injury in some patients with APSGN.     

Spectrum of renal involvement in familial Mediterranean fever.

Kidney biopsies were performed on fifteen patients with a long-standing history of familial Mediterranean fever (FMF) and evidence of renal involvement. On light microscopy, seven patients were found to have amyloidosis, six mesangial proliferative glomerulonephritis (MsPGN) and two patients rapid progressive glomerulonephritis (RPGN). Immunofluorescent studies of the six biopsies with MsPGN were positive for mesangial IgA deposits (IgA nephropathy) in three patients and IgM mesangial deposits in three (IgM nephropathy). We conclude that in patients with FMF and renal involvement, non-amyloid renal lesions (IgA nephropathy, IgM nephropathy and RPGN) should be considered in the differential diagnosis in addition to amyloidosis.     

Fibronectin-immunoglobulin complexes in the early course of IgA and Henoch-Schönlein nephritis

We have previously reported the presence of circulating IgA-fibronectin complexes in adult patients with primary IgA nephropathy. In the present study five children were serially investigated during the early course of IgA nephropathy and Henoch-Schönlein glomerulonephritis. Using affinity chromatography procedures and enzyme-linked immuno-sorbent assay, IgA, IgG and IgM in complex with fibronectin were repeatedly demonstrated during the follow-up period in both groups of patients. Most patients had, at the same time, IgA, IgG, as well as IgM deposits in the glomerular mesangium. The simultaneous presence of IgA and IgG in complexes purified from serum was furthermore demonstrated. The results are thus in contrast to the findings in adults with IgA nephropathy, in whom the immunoglobulin-fibronectin complexes only contained IgA. Whether this reflects different subgroups of patients or a different pathophysiology in children and adults remains to be elucidated.     

原发性IgA肾病与非IgA系膜增生性肾小球肾炎的临床病理分析

目的 比较原发性IgA肾病与非IgA系膜增生性肾小球肾炎（non-IgA mesangial proliferative glomerulonephritis,non-IgA MsPGN）的临床及肾脏病理改变特点.方法 选择我科经肾活检确诊的原发性IgA肾病患者（A组）和non-IgA MsPGN患者（B组）进行临床与病理资料对比分析.结果 A、B组的性别、前驱上呼吸道感染诱因、起病时伴发高血压、镜下血尿、血肌酐无统计学差异（P＞0.05）.B组较A组起病年龄小,起病时伴发肉眼血尿比率低,肾病综合征发生率高,血IgG水平低,差异均有统计学意义（P＜0.05）.A组肾小球、肾小管间质、肾小动脉病理改变发生率高于B组（P＜0.05）,IgM、C3沉积、系膜区电子致密物沉积、大块状致密物、足细胞微绒毛化、肾小球基底膜分层发生率均较B组高（P＜0.01）.结论 IgA肾病与non-IgA MsPGN在临床表现、病理改变上存在明显差异,IgA肾病较non-IgA MsPGN病理损伤重.     

A comparative immunologic study of IgA nephropathy

A conglutinin binding assay has been used to detect circulating immune complexes (CIC) containing IgA, IgG, or IgM in sera from patients with IgA nephropathy. IgA class CIC were detected in 40.7% of patient. IgG class CIC were detected only in patients with glomercular IgG deposits. IgM class CIC were detected more often in patients with glomerular IgM deposits than in patients without glomerular IgM deposits. These results demonstrate an association between the immunoglobulin in CIC and those in glomerular deposits. CIC were not detected in sera from most patients with IgA nephropathy by a Clq binding assay, however, since this assay does not detect IgA class CIC. Immunoelectronmicroscopic studies of IgA nephropathy have shown that C3 deposits are localized to the same areas as IgA deposits. In conclusion, we suggest that mesangial IgA deposits are composed of immune complexes and may be derived from CIC.     

Glomerular IgA deposits in patients with celiac disease

Glomerular immunopathology was studied in 25 patients with newly diagnosed celiac disease. None had clinical signs of renal disease. Glomeruli were obtained by fine-needle aspiration biopsy. The specimens were processed and studied by indirect immunofluorescence for immunoglobulins and complement. Mesangial IgA was found in 8 of the patients. It occurred occasionally together with slight IgG or IgM, but C3 was not seen in these patients. IgA-class circulating immune complexes (CIC), antireticulin antibodies (ARA), antigliadin antibodies (AGA), and rheumatoid factor (RF) occurred significantly more often in the patients with mesangial IgA than in the 17 patients having no mesangial IgA. The patients with mesangial IgA also had significantly higher mean levels of serum IgA, IgA-ARA and IgA-AGA than those without. The results suggest that glomerular mesangial deposits of IgA occur frequently in untreated celiac disease and that they are in some way associated with circulating IgA-class antibodies and immune complexes. In this situation IgA seems to be deposited without being able to induce clinically overt glomerulonephritis, a circumstance that may be related to the lack of complement in the deposits.     

Glomerular deposition of mannose-binding lectin in human glomerulonephritis.

BACKGROUND: Mannose-binding lectin (MBL), a member of the collectin family, binds to various oligosaccharides and activates the classical pathway of complement independent from C1q. At present it is unknown whether this so-called lectin pathway of complement activation plays a role in the pathogenesis of human glomerulonephritis. METHODS: Direct immunofluorescence of 84 renal biopsies using an MBL-specific monoclonal antibody and antibodies directed against IgG, IgA, IgM, C1q, C3, and terminal complement complex (TCC) was performed. Serum MBL levels of 50 patients were determined by enzyme-linked immunosorbent assay. RESULTS: MBL was detected in the glomeruli of patients with lupus nephropathy (15 of 16), membranous nephropathy (10/15), membranoproliferative glomerulonephritis type I (5/6) and anti-GBM nephritis (2/4). MBL deposition paralleled that of immunoglobulins, C1q, C3, and TCC but was less intense as compared to C1q. Focal segmental deposits of MBL were present in focal segmental glomerulosclerosis (4/6), IgA nephropathy (3/11), amyloidosis AL (1/4), and advanced renal fibrosis (2/2). Here MBL staining was identical to IgM and C3 and considered an unspecific entrapment of MBL in sclerotic lesions in these cases. No significant difference in MBL serum levels was observed between normal controls and patients with lupus nephritis, membranous nephropathy, membranoproliferative glomerulonephritis, focal segmental sclerosis, minimal change disease or IgA nephropathy. In patients suffering from membranous nephropathy with (n=10) or without (n=5) glomerular MBL deposits serum creatinine, C3, C4, serum protein, and proteinuria were not statistically different. CONCLUSION: MBL is present in the glomeruli of patients with glomerulonephritis involving deposition of IgG and activation of the classical pathway of complement. We propose that MBL binds to agalactosyl oligosaccharides of IgG that terminate in N-acetylglucosamine. The extent to which the lectin pathway of complement contributes to overall complement activation in the glomeruli remains unknown, but is likely to be marginal.     

Studies on circulating immune complexes. I: Circulating immune complexes in various types of glomerulonephritis and collagen disease: a comparative study employing conglutinin solid phase radioimmunoassay and raji cell radioimmunoassay

A study was undertaken to examine the differences in serum levels of circulating immune complexes (CIC) detected by different methods in various types of collagen disease and primary glomerulonephritis. The subjects used were 16 patients with SLE, 22 with IgA nephropathy, 8 with membranoproliferative glomerulonephritis, 8 with membranous nephropathy, 6 with minimal change nephrotic syndrome, and 2 each with RA, PSS, DM, Sj?gren syndrome, PN, MCTD and overlap syndrome, respectively. CIC were measured by two assays, namely, bovine conglutinin solid phase radioimmunoassay (C-assay) and Raji cell radioimmunoassay (R-assay). In SLE, the incidence and amounts of CIC detected were higher in R-assay than in C-assay. Similar results were obtained for the other types of collagen diseases. Furthermore, a discrepancy in the incidence of CIC detected by the two assays was found in 30% of patients with collagen diseases. Concerning the detection of CIC in primary glomerulonephritis, the sensitivity of C-assay was higher than that of R-assay. This discrepancy appears to reflect the different sensitivities of the two assays. No significant correlation was found between the CIC level and the intensity of IgG deposits in various types of glomerulonephritis. These results suggest that the R-assay was better for the detection of CIC in collagen diseases, and that the C-assay was suitable for that in primary glomerulonephritis.     

The role of sulfatides in autoimmunity in children with various glomerular disease]

Previous studies have suggested that autoimmunity to a number of kidney antigens may exist in glomerular disease. Our own work suggested that sulfatide which is one of the major acidic glycolipids of human kidney may be antigenic. Glycolipids were isolated from lipid extract of human kidney using thin-layer chromatography (TLC). As the major acidic glycolipids, sulfatide, CDH-sulfate, GM3, GD3 were identified. Acidic fraction of lipid extract were chromatographed and then tested for antigen by immunostaining. Sera from patients with IgA nephropathy (IgAN) and Henoch-Sch?nlein purpura nephritis (HSPN) contained antibody to the sulfatide of human kidney as determined by the direct binding of antibody to TLC. In addition, we measured the presence of sulfatide antibodies by enzyme linked immunosorbent assay (ELISA) in sera of patients with various glomerular disease: IgAN, HSPN, mesangial proliferative glomerulonephritis, membranoproliferative glomerulonephritis (MPGN), focal and segmental glomeruosclerosis (FSGS), membranous nephropathy (MN), minimal change nephrotic syndrome (MCNS), acute post streptococcal glomerulonephritis (PSAGN), and lupus nephritis (LN). IgM class sulfatide antibody were demonstrated in many cases of them. The incidence of IgA class sulfatide antibody in HSPN and IgAN was significantly high, and also the high incidence of IgG class sulfatide antibody occurred in IgAN. On the other hand, we evaluated cellular hypersensitivity to sulfatide in IgAN, HSPN, and FSGS using an active E-rosette assay. Positive results occurred in IgAN and HSPN. It was suggested that delayed hypersensitivity to sulfatide may generate an autoimmune inflammatory process. It has been reported that laminin binds specifically to sulfatide. Autoimmunity to sulfatide may disturb the laminin binding and consequently interfere with renal function. These results suggested sulfatide antigen may play important role in occurrence and aggravation of glomerular disease.     

Clinical-pathologic features and outcomes of IgA nephropathy patients with IgM deposition

Objective To determine the correlation of IgM deposition with clinic-pathological features and outcomes of IgA nephropathy patients. Methods A total of 1060 patients, who were diagnosed as IgA nephropathy by renal biopsies between 2001 and 2007 in Guangxing Hospital were enrolled. According to immunofluorescent test, patients were divided into patients with mesangial IgM deposition and patients without IgM deposition. Renal survival curves were assessed by Kaplan-Meier method. The effect of IgM deposition on outcomes of IgA nephropathy patients was examined by univariate and multivariable Cox proportional-hazards regression. Results Among 1060 IgA nephropathy patients, there were 750 patients with IgM deposition and 310 patients without IgM deposition. (1) Urinary protein and uric acid in patients with IgM deposition were significantly higher than those in patients without IgM deposition (all P＜0.05). Other clinical indicators shown no statistical difference (all P＞0.05). Moreover, IgM deposition patients had higher serum IgA, serum IgG and serum IgM (all P＜0.05). (2) In pathological indicators, IgM deposition patients had more segmented sclerosis or adhesions (S1 of Oxford classification), activity lesions as inflammatory cell infiltration and mesangial proliferation, and chronic pathological changes as tubular atrophy, segmented glomerular damage than patients without IgM deposition (all P＜0.05). (3) All patients were followed-up for a median of 89.7(61.8, 113.4) months, Kaplan-Meier analysis revealed that kidney survival rate was significantly lower in IgM deposition patients compared with patients without IgM deposition (Log-rank χ2=4.95, P=0.026). In a univariate Cox hazards regression mode, IgM deposition was a risk factor for poor prognosis of IgA nephropathy patients (HR=1.597, 95%CI 1.053-2.422, P=0.027). However, in a multivariable Cox analysis, IgM deposition shown no influence on outcomes of IgA nephropathy patients (HR=1.409, 95%CI 0.921-2.156, P=0.114). Conclusions IgA nephropathy patients with IgM deposition have higher urinary protein, and more serious pathological damage and immune fluorescence deposition. IgM deposition affects renal survival of IgA nephropathy, while IgM deposition is not an independent risk factor for prognosis of IgA nephropathy.     

Oral challenge with cow's milk in patients with IgA nephropathy--estimation of serum antibodies to cow's milk protein]

The author investigated the serum levels of antibodies against casein, beta-lactoglobulin and lactalbumin before and after challenging with cow's milk in 35 patients with IgA nephropathy, 18 with primary glomerulonephritis except for IgA nephropathy (GN control) and 11 healthy volunteers (H control). Blood samples were obtained at fasting, and at 30, 60, 120 and 180 min after oral challenging with 400 ml of cow's milk. IgA and IgG anti-cow's milk proteins antibodies were analyzed by ELISA. The same challenge was tested after administration of the antiallergic agent, sodium cromoglycate (SCG), in 11 patients with IgA nephropathy and 4 H controls. Serum levels of IgA anti-casein, -beta-lactoglobulin and lactalbumin antibodies in patients with IgA nephropathy were significantly higher than in control groups before challenging. However, those of IgG antibodies were not. The percent change of antibody titer after challenging with cow's milk did not elevate in any group, except for the level of IgA anti-beta-lactoglobulin antibody at 60 min in IgA nephropathy. Cases in which challenging produced marked elevation above the M + 2SD of the levels found in H control were expressed as "positive". The number of "positive" cases was 16 (45.7%) with IgA nephropathy, but none with GN control. There was no significant correlations between "positive" and "negative" cases with IgA nephropathy in clinical manifestations. In 3 out of 4 "positive" patients with IgA nephropathy, the levels of IgA antibody were suppressed after administration of SCG. It is concluded that the serum levels of IgA antibodies against cow's milk proteins are significantly elevated in IgA nephropathy, and are inhibited in elevation after oral challenge with cow's milk by administration of an antiallergic agent in some patients with IgA nephropathy.     

Glomerulonephritis and IgA deficiency

A mild self-limiting mesangial proliferative glomerulonephritis is described in 3 patients with selective IgA deficiency (less than 0.05 g/l). In all cases there was irregular thickening of peripheral glomerular capillary loops and paramesangial deposits. Arteriolar hyalinosis was present in two of the three cases. By direct immunofluorescence, and immunoperoxidase techniques in one case, IgM was present in the glomeruli and C3 was present in blood vessel walls. Secretory component was not detected in the glomeruli of any of the patients. The polyethylene glycol (PEG) precipitation immune complex assay was positive for IgM and IgG immune complexes in one patient and weakly positive for IgM immune complexes alone in another. The serum of one patient contained milk precipitins. All three patients had suffered from recurrent upper respiratory tract infections. It is suggested that the glomerular IgM immune complex deposition is related to the IgA deficiency and that, although the immune complexes may be a consequence of antibodies to dietary bovine proteins, this could be due to recurrent upper respiratory tract infections. This type of glomerulonephritis appears to resemble IgM associated glomerulonephritis in some aspects. Careful appraisal is required to establish if this association constitute a specific entity.     

The incidence of immunoglobulin-A deposits in glomerular diseases and its morphological examination

The presence of IgA with IgG, C', IgM and fibrin in 365 renal biopsy specimens has been studied by the immunohistological method. Glomerular IgA deposits were found in 38 cases (10.4%). The patients were divided into two groups according to the localization of IgA: 13 cases (3.56%) belonged to the first group, in which IgA showed diffuse mesangial localization. Light microscopic examination showed various stages of proliferative glomerulonephritis. These cases corresponded to the nephropathy described by Berger. In 25 cases (6.85%), belonging to the second group, the glomerular localization of IgA was found to be segmental and peripheral, appeared always in patches and was present with various histological alterations. Differentiation of the two kinds of alteration is possible primarily on the basis of the immunohistological pattern, but light microscopic and electron microscopic examination might also be helpful.