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This was an analysis of the renal investigations performed in 248 cyclosporin A (CyA)-treated patients who had recent-onset type I insulin-dependent diabetes mellitus (IDDM) to assess the clinicopathological relationships, risk factors and predictive indices of CyA nephrotoxicity, and renal function observed with different CyA treatment regimens. There were four different protocols, using initial CyA dosages ranging from 7.5 to 10 mg/kg/day, with dose modification according to serum creatinine concentration, which was measured regularly in some patients for up to 9 years after starting treatment. Kidney biopsies were obtained from 125 patients (74 adults and 51 children) who had received only CyA for an average duration of 13 months before biopsy and had no other sources of renal injury at this stage of IDDM. Of these patients, 58% showed normal or minimal changes on biopsy, 26% showed slight abnormalities, and 16% showed medium-grade (grade III nephropathy) abnormalities. Lesion severity was related to the degree of interstitial fibrosis and tubular atrophy which, in turn, was related to the use of high maximum CyA dosages. Patients' age, and excessive CyA dose and blood trough levels were the main risk factors, and serum creatinine increase was the best predictive factor of CyA-induced nephropathy. However, CyA-induced renal dysfunction was essentially reversible on dosage reduction, and morphological changes were not followed by progressive renal insufficiency when CyA doses were low and adjusted according to serum creatinine levels. We conclude that, at present, it is recommended that low-dose CyA in combination with other non-nephrotoxic immunosuppressive strategies be used in patients with IDDM.

An advisory board of nephropathologists with personal experience in the evaluation of biopsies from patients treated with cyclosporin A (CyA) was set up to address the following problems: 1. Definition of CyA nephropathy as seen in patients with autoimmune diseases; 2. Evaluation of the reliability and reproducibility of the diagnostic criteria for the different morphological lesions seen in CyA nephropathy; 3. Classification of the morphological lesions according to their clinical relevance; 4. Estimation of the possible progression of CyA nephropathy with continuous CyA therapy. The most frequent lesions attributable to CyA therapy in patients with autoimmune diseases are tubular atrophy, interstitial fibrosis, and arteriolar hyalinosis. All other lesions are rare. The reproducibility and diagnostic reliability is high for tubular atrophy and interstitial fibrosis, but low for arteriolar lesions even among experienced nephropathologists. The biopsies may be classified according to the severity of tubular atrophy, interstitial fibrosis and arteriolar hyalinosis with regard to their clinical relevance: In group I (within normal limits), CyA therapy can be continued; in group III (moderate-to-severe CyA-related lesions), CyA should be stopped if possible. Among group II biopsies (slight CyA-related abnormalities), no recommendation can be made in the absence of a second biopsy after a further year of CyA therapy. No clear-cut answer can be given concerning the progression of CyA-induced lesions. However, no significant progression has been found in the cases studied to date.

Twenty-nine patients with anti-glomerular basement membrane (GBM) disease, defined by circulating anti-GBM antibodies and/or linear deposits of immunoglobulin G along GBM, were studied retrospectively to identify prognostic indicators of renal outcome and pulmonary involvement. Patients consisted of 18 males and 11 females aged 6 to 76 years (mean 35.2 +/- 20.2). Goodpasture syndrome developed in 14, disease was confined to renal manifestations in 14 and isolated pulmonary involvement was present in a single case. Pulmonary disease was significantly associated with current smoking (p < 0.01). Among the 29 patients, end-stage renal failure requiring dialysis was initially observed in 16 (55%). Ten of them had anti-GBM glomerulonephritis (GN) and 4 presented with Goodpasture syndrome; the two other patients died very soon after the beginning of the disease. The 17 patients with an unfavourable renal evolution (group 1) and the 12 patients with favourable evolution or chronic renal failure (group 2) were compared. No significant difference was noted between the two groups concerning the age at onset of the disease, sex, cigarette smoking or pulmonary involvement. Conversely, creatininemia over 600 mumol/l, oligoanuria, absence of normal glomeruli, a high percentage of circumferential crescents, circulating anti-GBM antibodies detected by immunofluorescence, and a high level of circulating anti-GBM antibodies evaluated by ELISA were features which indicate an unfavourable renal course (p < 0.01).

Eleven cases of renal light chain deposition without amyloïdosis are reported (7 multiple myeloma, one Waldenström's disease, 3 without multiple myeloma without spike in serum or urine). Ten had kappa light chain deposits and 1 lambda light chain deposits along tubular basement membranes and in glomeruli. Ultrastructural study showed granular electron dense material on the external side of tubules with a very dark appearance in 4 cases and lighter appearance in the others. Five cases had nodular glomerulosclerosis with a finely granular, light appearance, corresponding to membrane-like material with kappa fixation in 4. Granular light chain deposition is analogous to type AL amyloïdosis in that their distribution is identical and both originate from light chains. The major difference between AL type amyloïdosis and light chain deposits lies in their ultrastructural appearance. Amyloïd substance is characterized by a fibrillar appearance and light chain substance by a granular appearance.