Effect of different storage temperatures on immunofluorescence results in frozen sections of kidney biopsies

AIM: To investigate the effect of storage temperature in renal biopsy tissue frozen section on immunofluorescence results. METHODS: One hundred renal biopsy samples of Zhejiang Province People's Hospital from January to June, 2015 were enrolled. Two sets of cutting slices were stored in -70℃ low temperature refrigerator as experimental group and in -12℃ freezing cryostat as control group. The immunoglobulins(IgG, IgA and IgM) and complements(C3, C4 and C1q) as well as fibrinogen were detected with direct immunofluorescence in the next day. The type Ⅳ collagen a3 and a5 chains were also detected by indirect immunofluorescence, and the qualitative and semi-quantitative results were observed under the fluorescence microscope. RESULTS: There were 16 cases of 3+~4+IgG in the experimental group, while the corresponding IgG was all 1+~2+in control group, significantly weaker than that in experimental group. There were 99 cases of 3+~4+a3 and 3+~4+a5 in experimental group, white there were 92 cases of 1+~2+a3/a5 and 8 cases negative in control group. The positive intensity was decreased in control group with statistical difference between the 2 groups(P<0.05). There were 15 cases of 4+IgA, 19 cases of 3+IgA, 15 cases of 3+IgM, 11 cases of 2+IgM, 13 cases of 4+C3, and 12 cases of 3+C3 in experimental group. The control group were similar to the results of experimental group, and no difference between the 2 groups was observed. CONCLUSION: The immunofluorescence results of renal biopsy frozen sections are highly affected by the section storage temperature, which has greater influence on the immunofluorescence positive intensity of IgG and type Ⅳ collagen. The renal biopsy frozen section should be stored in -70℃ low temperature refrigerator.