Objective To explore the feasibility of immunofluorescent staining (IF) in formalin-fixed and paraffin-embedded kidney tissue. Methods The formalin- fixed and paraffin-embedded renal biopsy specimens of 10 patients with membranous nephropalhy, 25 IgA nephropathy and 10 lupus nephritis were selected for this study. First, the best working conditions including the deparaffinized duration with dimethylbenzene, the antigen restoring methods with enzyme or microwave, and the optima] concentrations of FITC-conjugated antibodies were investigated. Then, the direct IF was performed on the deparaffinized and antigen-restored sections (DARS) and compared to the direct IF on snap-frozen sections (SFS). Results In this study,the best deparaffinized duration with dimethylbenzene was 30 min, and the best antigen restoring method was incubation with pepsin (0.4%,pH2) for 10 min. The FITC-conjugated antibodies should be diluted to show the strongest specific fluorescence with weakest background of nonspecific fluorescence. The coincident rate of immunopathological diagnosis was 100% between the IF on the DARS and the SFS. In addition, the IF on DARS had the following benefits: easiness to judge results because of its better preserved tissue structure and clearer IF appearance; a longer IF fading time which will be propitious to observe IF results and take photographs. Conclusions The IF on DARS should become a complementary method of IF on SFS. Because the bother with long-distance transport of frozen tissue is avoided, it will be very convenient for the local hospitals to send the renal biopsy tissue to the big nephrology centers for IF examination, which has a greatly realistic significance in the current China.

Objective To investigate the relationship of up-regulated thrombospondin 1 (TSP-1) expression with renal interstitial fibrosis and peritubular capillary loss in chronic aristolochic acid nephropathy(CAAN). Methods Thirty-six male SD rats were randomly divided into two groups, 18 in each one. CAAN rats received 20 mg?kg-1?d-1 aristolochic acid (AA) contained in ethanol extract of Aristolochia manshuriensis Kom by gavage for 5 days in the 1st week, and after a break of 9 days, then 15 mg?kg-1?d-1 AA for 7 days in every other week up to the 12th week. Control group rats (Con) only received tap water by gavage as above. At the end of the 4th, 8th and 12th week, 6 rats in each group were sacrificed. Immunohistochemical staining was performed in rat renal tissue sections to examine the expression of TSP-1, transforming growth factor-?1 (TGF-?1), aminopeptidase P(APP), vascular endothelial growth factor (VEGF) and type I collagen (Col I ). Results Compared with Con, the expression levels of interstitial TSP-1, tubular TGF-P1 and interstitial Col I were all up-regulated in CAAN rats (all P