Immunotactoid Glomerulopathy Research Articles

Immunotactoid glomerulopathy in a child with Down syndrome

A 9-year-old girl with Down (21-trisomy) syndrome was found to have proteinuria and microscopic haematuria at age 6 years. Proteinuria gradually increased during the next 3 years, although blood pressure and renal function remained normal. The patient exhibited no underlying systemic diseases, monoclonal gammopathy, cryoglobulinaemia or histological evidence of plasmacytoma. A percutaneous renal biopsy revealed immunotactoid glomerulopathy (fibrillary glomerulonephritis) characterized by thickening of the glomerular basement membrane, diffuse mesangial expansion and various-sized acid-Schiff-positive nodules that were intensely positive for IgG, light chains (kappa and lambda) and complement components (C3, C4, C1q) along the glomerular capillaries in the mesangium. Congo red dye and amyloid thioflavine T staining were negative. Fibrils (15-17 nm in diameter--larger than amyloid fibrils) were present in the mesangial area and within the glomerular basement membrane. We are not aware of a previous report of immunotactoid glomerulopathy and a patient with chromosomal abnormalities.

Immunotactoid Glomerulopathy (ITGP): A Not Fully Defined Clinicopathologic Entity

Immunotactoid glomerulopathy is characterized by the ultrastructural finding of fibrillary or microtubular deposits in patients without systemic diseases such as SLE, diabetes, paraproteinemias, cryoglobulinemia, or amyloidosis. These deposits correspond in most (but not all) cases to immunoglobulin and complement deposits as shown by immunohistochemical techniques. Different light microscopic patterns (mesangioproliferative, membranous, membranoproliferative, and crescentic) have been reported. Clinical presenting feature is characterized by proteinuria (often of nephrotic range), hematuria, and hypertension in most cases. Chronic renal failure requiring hemodialysis or transplantation is described in more than half the patients. Pathogenesis has not yet been elucidated and only some speculative hypotheses have so far been suggested. At present there is no clear evidence that we are dealing with a new pathologic entity, but larger series must be collected and studied in order to find a correct taxonomic collocation of this glomerulopathy.

Clinical and pathologic features of fibrillary glomerulonephritis

A diagnosis of fibrillary glomerulonephritis was made in 31 renal biopsies from 28 patients on the basis of the electron microscopic identification of glomerular deposits of randomly arranged fibrils that resembled amyloidosis but were larger. This accounted for approximately 1% of all nontransplant renal biopsy diagnoses. Renal biopsy specimens with parallel arrays of 30 nm to 50 nm microtubules (that is, immunotactoid glomerulopathy) were not included in the study. The patients had a mean age of 49 years with a range of 21 to 75. The male to female ratio was 1:1.8 and the ratio of Whites to Blacks was 8.3:1, which differs from the 3:1 ratio in our overall biopsy population. All patients had proteinuria (mean 6.0 g/day), and most had hematuria and renal insufficiency. After a mean follow-up of 24 months, there was 48% renal survival. The light microscopic appearance of the fibrillary glomerulonephritis was quite varied. Capillary wall thickening and matrix expansion were the most frequent alterations. Nineteen percent of specimens had crescents. Morphometric ultrastructural analysis demonstrated a mean fibril diameter of 22.4 +/- 7.4 nm. Immunofluorescence microscopy revealed that IgG was the dominant and often the only immunoglobulin class in immune deposits, and subclass analysis revealed that IgG4 was the dominant or exclusive subclass in all specimens tested. We hypothesize that the relatively homogeneous nature of the immunoglobulin in the immune deposits is the basis for the fibril formation.

Immunotactoid glomerulopathy: Recurrence of disease in renal transplant

Immunotactoid glomerulopathy (ITG) is a disease of the kidney, first described 1980. It is characterized by the specific deposition of immunoglobulin in the renal glomeruli, producing diffuse mesangial expansion similar to that commonly noted in the sclerosing process of amyloidosis. However, these patients do not exhibit the clinical symptoms of patients with extra renal, or systemic disease, and therefore have a better prognosis. The demonstration by electron miscroscopy of fibrillar deposits that are thicker than that of amyloid is crucial to the diagnosis.The association of this disease to an autoimmune response is demonstrated by the immunofluorescent staining of antihuman IgG and C3 to the affected glomeruli. Other immunoglob ins may be implicated, but are not as common.

Immunotactoid (Microtubular) Glomerulopathy: An Entity Distinct From Fibrillary Glomerulonephritis?

Immunotactoid glomerulopathy (IT), or alternatively, microtubular glomerulopathy, is a term that has been used by some investigators to encompass those glomerulopathies characterized by the presence of fibrillar or microtubular deposits which are distinguished from amyloid principally by their larger size and lack of reactivity with the Congo red reagent. A case is presented here of IT as it was initially described. The present case, and a review of the literature, suggest that the diagnosis of IT be restricted to those glomerulopathies associated with large, at times organized, microtubular deposits. Terms such as fibrillary glomerulonephritis, or alternatively Congo red-negative amyloidosis-like glomerulopathy, could then be used to describe those patients with smaller, fibrillar glomerular deposits having an appearance closely resembling amyloid. We believe it is possible to separate the entities fibrillary glomerulonephritis and IT on morphological grounds. This is a potentially useful distinction that identifies patients who are likely to have or develop clinical evidence of a lymphoplasmacytic disorder or dysproteinemia, which are associated with deposits of IT, and distinguishes them from patients with fibrillary glomerulonephritis, of whom only a single case has been linked to such clinical findings.

Fibrillary Glomerulonephritis: A Case Report

CONGO RED-NEGA TIYE fibrillar deposits in the kidney have been described in the literature in the past 4 years. I,2 Using electron microscopy, Alpers et all described fibrillary glomerulonephritis as random fibrillar material in the mesangium and capillary walls that stains Congo red-negative. Fluorescence microscopy of this fibrillar material showed granular deposits of immunoglobulin and complement in the same distribution. Similarly, Korbet et at2 described immunotactoid glomerulopathy with pathologic features identical to those found in fibrillary glomerulonephritis. We present the case of an asymptomatic 66year-old woman with fibrillary glomerulonephritis on renal biopsy and laboratory evidence of a positive antinuclear antibody (ANA) titer, as well as persistent hypocomplementemia. This case is unique in that our patient has persistent hypocomplementemia, indicating a possible association of fibrillary glomerulonephritis with systemic disease.

Immunotactoid Glomerulopathy

During the past 10 years, immunotactoid glomerulopathy has become recognized with increasing frequency. The lesion is characterized histologically by highly organized ultrastructural deposits that appear to be composed of immunoglobulin and complement and are negative for amyloid by Congo red stain. Clinically and/or serologically, patients have no evidence of cryoglobulinemia, amyloidosis, systemic lupus erythematosus, or a paraproteinemia, disorders associated with glomerular deposits, which also have a highly organized tactoidal or fibrillar characteristic. Immunotactoid glomerulopathy does not appear to be a multisystemic disease process and thus may represent a primary glomerulopathy. Patients with immunotactoid glomerulopathy present with proteinuria (nephrotic range in more than 60%) and over half of the patients have hypertension, hematuria, and renal insufficiency. Progression to end stage renal disease has occurred in more than 40% of patients reported to date. The experience in treating this disorder using prednisone and/or immunosuppression is limited and has not been impressive. Four patients have successfully undergone renal transplantation, but proteinuria recurred in two and was associated with the recurrence of immunotactoid glomerulopathy in the renal allograft. Although we have gained insight into the clinical course and histopathology of this disorder over the past few years, we still know little about its pathogenesis, an area for further research.

Immunotactoid Glomerulopathy and Cutaneous Vasculitis

A 22-year-old woman presented glomerulonephritis with Schönlein-Henoch-like syndrome and monoclonal abnormality. One month later, she developed a rapidly progressive glomerulonephritis with hypertension and persistent purpura. In the two renal biopsies performed during the first and the second attack, mesangial expansion and thickening of the glomerular capillary walls (associated with 50% of crescents in the second biopsy) were observed on light microscopy. By immunofluorescence faint deposits of immunoglobulins (light and heavy chains) and complement components were found present in the mesangium. Electron microscopy showed tubular microfibrils measuring 19-24 nm in the mesangium, subendothelial and subepithelial areas. A skin biopsy performed during the first attack demonstrated leukocytoclastic skin vasculitis. By immunofluorescence, no deposits were observed. Congo red staining for amyloid and cryoglobulinemia were negative. This case is similar to an entity recently described and named immunotactoid glomerulopathy.

Immunotactoid glomerulopathy associated with mycosis fungoides

A patient with mycosis fungoides developed a nephrotic syndrome. Renal biopsy revealed deposits of a highly organized fibrillar material which did not stain with the typical amyloid stains; this picture was consistent with the diagnosis of non-amyloidotic fibrillary glomerulopathy or immunotactoid glomerulopathy. We believe this is the first case reported of immunotactoid glomerulopathy associated with mycosis fungoides. Possible pathogenetic implications are discussed with reference to previous publications.

Renal Pathology with Clinical and Functional Correlations.

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Immunotactoid glomerulopathy with fingerprint immune deposits

Immunotactoid glomerulopathy is a distinct clinico-pathological entity which has recently been defined. The term immunotactoid refers to highly organized immune depositions appearing as rod-like microtubular structures in ultrastructural examination. We describe a patient with mixed connective tissue disease who demonstrates characteristic features of immunotactoid glomerulopathy. The diagnosis was made after excluding amyloidosis, cryoglobulinaemia and lupus nephritis. In addition to immunotactoid microtubules, ultrastructural examination also demonstrated presence of fingerprint depositions which were intimately mixed with immunotactoid structures. Fingerprint deposits have been described in lupus nephritis and cryoglobulin-related nephropathy, but rarely in other glomerulonephritis. These unique findings in our patient may suggest a previously unsuspected relationship between the syndrome of immunotactoid glomerulopathy and systemic lupus erythematosus.

Immunotactoid glomerulopathy.

We present 11 patients with immunotactoid glomerulopathy, a new syndrome characterized clinically by proteinuria (11/11), microscopic hematuria (9/11) and hypertension (9/11). The patients consisted of six females and five males, aged 25 to 59 years (mean, 44.6). Proteinuria was the presenting feature and the reason for renal biopsy in all patients. The diagnosis of immunotactoid glomerulopathy was established at renal biopsy by the presence of glomerular extracellular microtubules composed of immune reactants. All the biopsies studied by immunofluorescence (10 cases) had glomerular deposits of IgG and C3. In three biopsies studied with IgG subclass specific antisera, only one patient had monoclonal immunoglobulin deposits (IgG3 kappa). In six cases the glomerular deposits were analyzed for light chains. In three the deposits contained kappa only, and three consisted of both kappa and lambda. In two cases the immune aggregates were confined to the mesangium, and in the remaining eight cases, the deposits were present in the mesangium and the glomerular basement membranes. Electron-dense deposits composed of microtubules were present in the same distribution within the glomerulus as the immune reactants. The microtubules had a uniform diameter in each biopsy, but they varied in size from case to case. They were approximately the same size in eight cases (mean, 22.3 +/- 3 [SD] nm). Three cases had much larger microtubules: 34.2 nm, 35.4 nm, and 48.9 nm in diameter. Although the 22.3-nm microtubules resembled amyloid in their appearance, glomerular distribution and random orientation in the tissue, they were more than twice the diameter of amyloid (8.9 nm), and Congo red and thioflavin T stains for amyloid were negative. Similar microtubular structures have been described in patients with cryoglobulinemia, SLE and paraproteinemia, but these diseases were excluded in our patients on clinical, serologic and in some cases histologic grounds. More important, none of our patients had clinical or histochemical evidence of amyloidosis, an entity which may be confused with immunotactoid glomerulopathy on a morphologic basis. Follow-up, from 22 to 94 months (mean, 52.6) was obtained in all 11 patients, and 2 clinical courses were noted. Six patients had progressive deterioration of renal function, with five requiring dialysis. This group had severe hypertension (4/6) and nephrotic-range proteinuria (5/6) at some point in their course. The remaining five patients with stable renal function had proteinuria of less than 2.0 g/24 hr in most cases (4/5), and none had severe hypertension. This dichotomy correlated with the distribution of immunotactoids.(ABSTRACT TRUNCATED AT 400 WORDS)