Study on the methods of antigen retrieval in paraffin section of kidney biopsy

Objective To compare the effect of various antigen retrieval methods in paraffin sections of renal biopsy tissue, and explore the best antigen retrieval method. Methods Forty-five renal biopsy specimens were collected from the First Affiliated Hospital of Zhengzhou University, including lupus nephritis (n=10), membranous nephropathy (n=10), IgA nephropathy (n=10) and amyloidosis glomerulopathy (n=15). Five retrieval methods (including high pressure thermal retrieval combined with trypsin retrieval, microwave thermal retrieval combined with trypsin retrieval, high pressure thermal retrieval, microwave thermal retrieval and gastroprotease retrieval) were used for immunofluorescence staining of paraffin sections. Renal tissue specimens were divided into six groups according to different antigen retrieval methods, frozen section specimens used as a control group. The immunofluorescence semi-quantitative scores of paraffin sections of the five heat-repairing antigen methods and frozen sections were compared. Results Immunofluorescence staining of hyperbaric thermal retrieval combined with trypsin retrieval group and microwave thermal retrieval combined with trypsin retrieval group were similar with those of frozen sections. Compared with the control group, there were no significant difference in the semi-quantitative immunofluorescence scores between the two groups (all P>0.05). However, Immunofluorescence staining of hyperbaric thermal retrieval, microwave thermal retrieval, pepsin digestion had significantly higher false negative rate than those of frozen sections. Compared with the control group, the difference in semi-quantitative immunofluorescence score was statistically significant (all P<0.05). Conclusion High pressure heat retrieval combined with trypsin retrieval or microwave heat retrieval combined with trypsin retrieval is the first choice of antigen retrieval methods. Key words: Biopsy; Paraffin embedding; Fluorescent antibody technique; Antigen retrieval