ABSTRACT
Objective To investigate the diagnostic technique of Alport syndrome(AS)by immunohistochemical staining of type Ⅳ collagen ? chains on paraffin-embedded renal sections.Methods Renal biopsies were obtained from 2 patients with autosomal recessive form of AS,2 female patients and 2 male patients with X-linked dominant form of AS and 2 patients with hematuria(1male and 1 female).AS was diagnosed according to symptoms,family history,pathology,immunofluorescence staining of type Ⅳ collagen ? chains on renal and skin biopsies and gene analysis.Normal portions of nephrectomized kidneys from 2 patients with renal tumor were used as controls.Type Ⅳ collagen ? chains were stained by two-step immunohistochemistry staining method on paraffin-embedded renal sections.Three antigen retrieval methods including autoclave heating,pepsin digestion and proteinase were investigated to find the best antigen retrieval method for type Ⅳ collagen ? chains.The findings were compared with those examined by immunofluorescence staining on fresh frozen sections.Results By immunohistochemistry staining,type Ⅳ collagen ?3 and ?5 chains showed continuous linear pattern along glomerular basement membrane on sections from the controls and the hematuria patients,intermittent linear pattern for X-linked dominant female AS patients,negative for X-linked dominant male AS patient.For patients with autosomal recessive AS,the staining of type Ⅳ collagen ?3 and ?5 chains were negative on glomerular basement membrane,but ?5 chain was positive on glomerular capsules and partial tubular basement membrane.The results were the same as those examined by immunofluorescence staining.Conclusion AS can be diagnosed by immunohistochemistry staining of type Ⅳ collagen on paraffin-embedded renal sections,which is a new technique for diagnosis of AS in China.