Micheline Levy

Worldwide perspective of IgA nephropathy.

It is becoming evident that IgA nephropathy (IgAN) is the most common glomerular disease, and a frequent cause of end-stage renal failure in both white and Asian populations. Its significance as a public health problem is not known since little epidemiologic research is available in most countries. The apparent geographic variations in the percentage of IgAN in kidney biopsy specimens may reflect different clinical policies for diagnostic tests. As a consequence, the frequency of IgAN cannot be accurately extrapolated from these data for any given population. The highest percentages, reported in Singapore and Japan, may be influenced by the systematic screening of urines in both countries. By contrast, IgAN has been detected rarely in blacks either from the United States or from Africa. However, biopsies are performed infrequently in African patients with only microscopic hematuria. Such ethnic differences may suggest a possible role of genetic factors in the etiology of IgAN. As shown recently in France and Italy, antibiotic therapy of streptococcal infections apparently has not influenced the percentage of IgAN in kidney biopsy specimens. These facts and the rarity of the glomerulonephritis in blacks suggest that infections may not be responsible for the etiology of IgAN. The traditional search for causal agents should be approached more vigorously. It will require innovative epidemiologic efforts to understand the mechanisms by which multiple factors (environmental and genetic) acting together influence the risk of disease.

Berger's disease in children: Natural history and outcome.

The clinical course and outcome of 91 children less than 15 years of age at onset and followed for at least 1 year have been retrospectively analyzed. The course has been characterized by recurrent macroscopic hematuria in 74 patients, by proteinuria-microscopic hematuria and a single episode of macroscopic hematuria occurring either at onset or a few months later in 8, by proteinuria-microscopic hematuria in 7, and by proteinuria only in 1. Lastly, one patient showed rapidly progressive renal failure. Four groups were identified by light microscopy: minimal glomerular changes (26), focal and segmental glomerulonephritis (41), pure mesangial proliferation (3) and proliferative glomerulonephritis with crescents (21). A good correlation was found between the glomerular lesions observed by light microscopy and the outcome. In this series we have not observed a dramatic clinical deterioration suggesting a transformation from one histologic type to another, as reported by others. None of the 70 patients belonging to the first three groups has impaired renal function but two with focal and segmental glomerulonephritis have developed hypertension. Although the clinical course is benign, many patients have, at the last observation, an abnormal urinalysis characterized by microscopic hematuria and/or mild proteinuria; the proteinuria is over 1 g/24 h in six patients with focal and segmental glomerulonephritis. Ten patients remained in clinical remission for several years, but mesangial IgA deposits were still present in the only patient who had a repeat biopsy while in remission. In contrast, none of the patients with proliferative glomerulonephritis with crescents has had a prolonged remission. Six patients developed terminal renal failure 0.7, 0.11, 2, 4, 8 and 10 years after onset. Two additional patients are in moderate chronic renal failure with hypertension 10 and 12 years after onset. Most children show a persistent nephropathy, (in five proteinuria is over 1 g/24 h), and two of them have developed hypertension. Therapeutic trials using drugs with side-effects should, therefore, be used only in this group of patients.

Membranous glomerulonephritis and hepatitis B surface antigen in children

Of 33 children with membranous nephropathy screened for HBs Ag, 14 were found to be HBs Ag carriers, whereas HBs Ag was detected in 3 of 170 and 4 of 100 children with glomerular and nonglomerular kidney diseases, respectively. HBs Ag was often associated with acute hepatitis at onset (five patients) or with elevated transminases values. This high incidence and the prevalence of an unusual subtype (ayw2) suggest a relationship between HBs Ag and the glomerular lesions. Using immunofluorescence, however, HBs Ag could not be detected within the deposits, so that the nature of the relationship cannot be considered as established. The clinical outcome (50% remission), the plasma complement component disturbances, and findings by immunofluorescence did not differ from those observed in children with MGN without detectable HBs Ag.

Immunopathological findings in idiopathic nephrosis: clinical significance of glomerular "immune deposits".

Idiopathic nephrosis (IN), which includes minimal change (MCD), diffuse mesangial proliferation (DMP) and focal segmental glomerular sclerosis (FSGS), is classically characterized by the absence of significant deposits by immunofluorescence microcopy (IF), except for the focal lesions of segmental sclerosis and/or hyalinosis of FSGS, which fix IgM and C3 antiserums. Since IF is available in most centres, an increasing number of unexpected findings has been reported. In order to evaluate the clinical significance of the glomerular deposits revealed by IF in some instances, we reviewed the renal biopsy findings of 222 consecutive children presenting with IN and in whom IF microscopy was available. By light microscopy, 122 patients showed MCD, 10 DMP, and 90 FSGS with DMP (11 cases) or without (79 cases). By IF, 125 specimens were negative and served as controls; 54 showed mesangial IgM deposits, 24 mesangial IgG deposits (associated with Clq deposits in 16), 15 scattered granules of C3 and 4 predominant deposits of mesangial IgA. We correlated these findings with initial response to steroid therapy and outcome and could find no significant difference between the various categories defined by IF and the control group. Repeat biopsies, performed in 21 cases, showed the persistence of deposits in 11 and their transformation in 10. The particular problem raised by the patients who present with IN and mesangial IgA deposits is discussed. Our results demonstrate that patients presenting with IN and “positive IF”, whether showing IgM, IgG and Clq, C3 or IgA, do not represent distinct clinicopathological entities.

Immunopathology of membranoproliferative glomerulonephritis with subendothelial deposits (Type I MPGN)

Abstract Immunofluorescence microscopy (IF) studies were carried out in 36 patients with Type I MPGN and showed the constant presence of deposits containing C3. Based on the presence or the absence of immunoglobulins (Ig), two main patterns were observed. Complement profiles (30 patients) and C3NeF activity (20 patients) were studied in the two groups defined by IF. Our findings indicate an activation of the complement system through the classical pathway even in the group characterized by the absence of Ig. Such an activation suggests the role of immune complexes in the pathogenesis of the disease. Because of the presence of C3NeF activity in occasional patients, a superimposed activation through the alternative pathway is not unlikely. In two additional patients, one with predominant IgA within the deposits and one with C2-deficiency, the complement system is probably activated through the alternative pathway.

Membranous glomerulonephritis with extra-renal disorders in children.

Thirty of 85 children with membranous glomerulonephritis (MGN) had associated extraglomerular disorders. The relation of these associations to membranous glomerulonephritis (MGN) is discussed. The causal relationship of acute hepatitis (5 cases), persistent hepatitis B antigenemia (6 cases), systemic lupus erythematosus (2 cases) and syphilis (1 case) may be ascertained; in similar conditions a definite antigen (Ag) has been found in MGN deposits. The association with SS or SA hemoglobinopathy (3 cases) ans with a preceding streptococcal infection (4 cases) raises the possible responsibility of renal tubular epithelium (RTE) Ag and of a streptococcal Ag. D-penicillamine therapy (1 case) is a well-known cause of MGN although the acting Ag remains unknown. Four children had serum sickness-like symptoms, two had hematologic disorders and two had proximal tubular dysfunction, one of them with proven anti-tubular and anti-alveolar basement membrane antibodies. A decrease in plasma C4, Clq, and factor B with normal C3 was frequently observed. The multiple Ag previously described as causative of MGN are recalled. The prevalent incidence of HBsAg is stressed, and the necessity for further investigations in patients with MGN in order to find an underlying disease is emphasized.

Immunologically Mediated Tubulo-Interstitial Nephritis in Children

14 children with proven or presumably immunologically mediated tubulo-interstitial nephritis are presented. In 2 patients anti-tubular basement membrane antibodies were detected. In 6 immunofluorescence microscopy showed granular deposits of immunoglobulin and/or complement likely representing interstitial location of immune complexes. The findings by immunofluorescence were not significant in the remaining 6 patients. However, the association of renal disease to extra-renal disorders, namely chronic active hepatitis and ulcerative colitis, or uveitis or the presence of an epithelioid granuloma with multinucleated giant cells suggests that in such patients an immunologic disorder might be responsible for the tubulo-interstitial nephritis.

Renal Involvement in Juvenile Chronic Arthritis: Clinical and Pathologic Features

Over an 18-year period, renal involvement was diagnosed in 13 patients, who represent 1% of the total juvenile chronic arthritis population referred to us. All had severe arthritis. This study illustrates the importance of renal biopsy and indicates that renal involvement in juvenile chronic arthritis is a heterogeneous group of diseases, with a variety of causes. In eight patients with nephrotic syndrome, renal biopsy revealed amyloidosis. One rapidly died of diffuse amyloidosis and infection. The other seven received chlorambucil. Disappearance of proteinuria was noted in three of them. Four patients have persistent proteinuria but normal serum creatinine. It is suggested that, despite the long-term oncogenic risk of the drug, chlorambucil may be beneficial in patients with amyloid deposits. In one patient, the nephrotic syndrome was attributed to systemic lupus erythematosus, and in another, the chance association of an arthritis and nephrotic syndrome with minimal glomerular changes was considered. Although drug responsibility is difficult to determine in these patients receiving several medications in association, the renal involvement presented by the remaining three patients was probably related to drug(s). Moreover, it is possible that the effect of the association of medications is deleterious to the kidney. Drug-induced nephropathy is usually reversible when drugs are stopped. Unfortunately, because of persistent joint pain, these patients will continue to require pain-relieving drugs over prolonged periods.

Highlights Immunologically Mediated Tubulointerstitial Nephritis in Children

Several immunologically mediated mechanisms may lead to injury of renal tubules and interstitial tissue resulting in tubulointer-stitial nephritis (TIN). The distinguishing features of these mechanisms are based upon their immunofluorescent microscopic (IF) pattern. Tubular linear deposits of immunoglobulins (Ig) suggest the presence of circulating antitubular basement membrane (TBM) antibodies. Granular deposits of Ig and/or complement (C) are likely related to the presence of immune complexes (IC). In the absence of deposits, a cell-mediated reaction may be suggested. These mechanisms have been well studied in experimental models. They may also be observed in man. We report about 14 children with proven or presumed immunologically mediated TIN.