Nicole Hinglais

Sequential immunological targeting of chronic experimental arterial allograft.

Arterial wall is the main site involved in the chronic rejection process. The rat aortic allograft model was used here to characterize and describe the sequential evolution of the different targets and effectors of arterial wall immunological injury and response during arterial allograft rejection. Rat abdominal aortae were isografted or allografted from Brown-Norway to Lewis rats. Endothelial and smooth muscle cell injury and humoral and cellular immunological effectors were characterized from 0 to 60 days after transplantation using a battery of specific antibodies. The intimal proliferative response was also characterized over this time. Isografted Brown-Norway aorta adventitia had very few cellular components, which suggests that donor adventitia would be poorly antigenic in allografts. In contrast, allograft adventitia was the site of a major inflammatory cell invasion in which the expression of an adhesion molecule by colonizing capillary endothelial cells could play a main role. This adventitial infiltration continued as long as medial smooth muscle persisted. The luminal endothelial cells disappeared early, probably associated with macrophage margination. In contrast, medial smooth muscle cell disappearance occurred later and was specifically targeted

Treatment of the childhood haemolytic uraemic syndrome with plasma

Seventy-nine children with haemolytic uraemic syndrome (mean age 28 months) were randomly assigned either to a group receiving plasma infusions (plasma group,n=39) or to a group treated conservatively (control group,n=40). The duration of haemolysis, thrombocytopenia and anuria was similar in the two groups. Serum creatinine levels were similar in the two groups at the 1-month follow-up but were higher in the control group at 3 months (plasma group 49±14, control group 66±28 μmol/l;P<0.02) and at 6 months (plasma group 48±13, control group 63±21 μmol/l;P<0.005). The prevalence of proteinuria was also higher in the control group at the 6-month follow-up (plasma group 17%, control group 46%;P<0.02). However differences were no longer significant after 1 year. Renal tissue was examined in 54 cases (plasma group,n=27; control group,n=27). Diffuse cortical necrosis was present in 7 cases in the control group but was absent in the plasma group (P<0.02). Taking into consideration the higher serum creatinine levels, the higher prevalence of proteinuria during the first 6 months of follow-up in the control group and the presence of diffuse cortical necrosis in this group compared with the plasma group, we conclude that plasma infusions should be regarded as beneficial. Further study is needed to determine which plasma fraction is involved.

Glomerular Lesions in the Transplanted Kidney in Children

The glomerular pathology of 634 transplant specimens (526 biopsies and 108 transplantectomies) from 410 children was studied. Three types of glomerulopathies were observed: (1) recurrent glomerulonephritis (GN) (40 of 142 patients with glomerular nephropathy), (2) de novo GN (52 grafts), and (3) transplant glomerulopathy (29 grafts). The study of recurrent GN is considered of great interest because of the possible insight into the nature of the original disease and the opportunity to observe the evolution of the disease in sequential biopsies of the transplant. The two major forms of de novo GN were membranous GN and IgG linear deposits along glomerular and tubular basement membranes. Transplant glomerulopathy, although distinctive morphologically, may resemble membranoproliferative GN (MPGN) or thrombotic microangiopathy.

Inflammatory cells and myocardial fibrosis: spatial and temporal distribution in renovascular hypertensive rats

OBJECTIVE The fibroblasts producing collagen are co-localized with inflammatory cells in myocardial fibrosis areas of spontaneously hypertensive rats, suggesting that collagen overproduction in this model may be modulated by inflammatory cells. The present study extends these observations to the Goldblatt model of hypertension in which the renin-angiotensin system is activated. METHODS Inflammatory cells were identified with monoclonal antibodies directed against macrophages (ED1+), T helper (CD4+) and cytotoxic lymphocytes (CD8+), and MHC class II-expressing cells (Ia+). The alkaline phosphatase-anti-alkaline phosphatase (APAAP) immuno-staining technique was used. A new computer-assisted morphometric method was utilized to quantify the inflammatory infiltrate in each cardiac compartment with polarized-light microscopy. Cells responsible for the collagen synthesis were identified by in situ hybridization. The collagen content was estimated by morphometry on left ventricle sections stained with Sirius red, and by biochemical quantification of the hydroxyproline concentration. RESULTS Computer-assisted morphometry under polarized light was well suited to quantify inflammatory cells labeled by the APAAP technique. Inflammatory cells were co-localized with collagen-synthesizing fibroblasts. The main inflammatory cells were CD4+ lymphocytes > Ia+ > ED1+ > CD8+ cells. These cell densities were increased in hypertensive rats in all cardiac areas compared to control rats except for IA+ cells which were concentrated in microscars. Macrophage density was correlated with plasma renin activity. The inflammatory cell density which best correlated with fibrosis was macrophage density, and which best correlated with systolic blood pressure was macrophage and T helper lymphocyte densities. CONCLUSIONS One can speculate that the correlation between macrophage density and blood pressure as well as with plasma renin activity may indicate that angiotensins and/or elevation of blood pressure could participate in the initial signalling which may mobilize inflammatory cells. These inflammatory cells could promote fibrosis by releasing mediators such as growth factors or cytokines which act upon fibroblasts.

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.

Cyclosporin in the treatment of idiopathic nephrotic syndrome in children

Thirty-five children (12 girls, 23 boys), aged from 1 year and 5 months to 14 years at the onset of idiopathic nephrotic syndrome, received cyclosporin A (CyA) because of steroid toxicity or failure to respond to steroids. The initial oral dose was 6 mg/kg per day and this was adjusted to obtain trough plasma levels of 50–150 ng/ml. The duration of treatment was between 2 and 8 months. In patients who responded to CyA treatment, the dosage was tapered off; treatment was stopped if found to be ineffective. Of the 35 children, 20 were frequent-relapsing steroid responders who suffered serious side-effects from steroid therapy. Seventeen of them either went into remission or did not relapse despite the withdrawal of prednisone. Prednisone doses could be lowered but not stopped in 1 patient and the remaining 2 patients relapsed when prednisone was tapered off. At the final examination, 10 of the 12 children in whom CyA was tapered off and who had initially responded to CyA had relapsed. A second course was given to these 10 patients and 3 failed to respond. Five children were partial steroid responders and CyA induced a remission in 1 and a partial remission in another. Among the 10 children who were steroid resistant, only 1 responded to CyA, 2 had a partial response and 7 failed to respond to CyA. A reduction of glomerular filtration rate occurred in 8 patients, 7 of whom had either persistent nephrotic syndrome or were in relapse, which suggests that factors other than CyA nephrotoxicity may have been operative. Complete reversal occurred in only 4 patients. Significant histological changes, likely to be related to CyA, were seen in 2 repeat renal biopsies out of the 11 performed.

Renin storage and cell differentiation in juxtaglomerular cell tumors: An immunohistochemical and ultrastructural study of three cases

Three renin-secreting juxtaglomerular cell tumors were studied by ultrastructural and immunocytochemical methods. Both active and inactive renins were identified in tumor extracts. By immunofluorescence and the peroxidase-antiperoxidase (PAP) method with antirenin antiserum, immunolabeling was intracytoplasmic and irregularly distributed throughout the tumor tissue. Electron microscopic examination revealed various types of secretory granules, including atypical giant crystalloid protogranules in one case, and the postembedding PAP procedure showed labeling of all types of granules. Acid phosphatase staining was observed within secretory granules and autophagic vacuoles. The process of renin storage and release is discussed. The presence in one case of a neural component and a distal tubular structure supports the view of a hamartomatous lesion.

Les lésions précoces de l’amylose expérimentale du hamster. Etude au microscope électronique

1. Une amylose renale est induite chez des hamsters dores par inoculation de Leishmania Donovani. Vingt-trois animaux ont ete infectes et leurs reins ont ete examines au cours de cinq series de prelevements pratiques de la troisieme a la treizieme semaine apres l’infection. 2. L’examen au microscope optique a montre cinq amyloses debutantes chez les dix animaux sacrifies a la douzieme et a la treizieme semaine. 3. L’examen au microscope electronique a ete fait sur les reins de huit hamsters: a) 2 hamsters ayant des reins normaux au microscope optique (9eme semaine); b) 4 hamsters ne montrant, au microscope optique, qu’une hypertrophie moderee des espaces intercapillaires mais sans lesions amyloides (12eme et 13eme semaine). c) 2 hamsters ayant une amylose debutante visible au microscope optique (13eme semaine). Les reins de deux animaux de la serie «b» ont de tres petits depots amyloides strictement localises dans les espaces intercapillaires; les reins des animaux de la serie «c» ont des depots amyloides a predominance intercapillaire et quelques depots plus diffus dans les parois capillaires peripheriques. Ces resultats soulignent le role particulier des espaces intercapillaires dans la localisation precoce de l’amylose renale experimentale; leur signification est discutee dans le texte. 4. Deux aspects inhabituels de la substance amyloide sont decrits. Le premier est caracterise par la presence de nombreuses petites vesicules (300 A environ) accolees aux fibrilles amyloides, le deuxieme par la penetration de fibrilles isolees dans le cytoplasme epithelial. 5. Une hypertrophie moderee des espaces intercapillaires et des excroissances nodulaires de la membrane basale sont retrouves chez tous les animaux sacrifies a la 12eme et 13eme semaine examines au microscope electronique, qu’ils aient ou non une amylose.