Quality management of MMR immunohistochemical staining

HAN Liyuan; FU Wen; CHEN Dong; QI Xiaoli; DONG Gehong; SONG Xin; ZHANG Yan; HUANG Ranran; LI Qian; LIAN Guoliang

doi:10.3969/j.issn.1007-8096.2025.10.013

Abstract：Objective To explore the correlation between various factors in the staining process and staining results,and to clarify the current status of immunohistochemical staining of MMR in pathology laboratories in Beijing.Methods The MMR chip quality control sections were provided by the Beijing Pathology Quality Control and Improvement Center.The pathology laboratories in Beijing voluntarily participated in the study,and stained the MMR quality control sections using their daily reagents and staining procedures.The relationship between the qualification status of stained sections and factors including laboratory grade,operator work experience,use of automated staining,antibody clone number,antigen retrieval conditions,use of biotin blocking,and DAB chromogenic conditions was analyzed.Results A total of 284 immunohistochemical-stained slices were received from 71 institutions.The qualification rates for MLH1,MSH2,MSH6,and PMS2 were 95.8%(68/71),94.4%(67/71),93.0%(66/71),and 74.6%(53/71),respectively.About 66.2%(47/71)of immunohistochemical technicians had more than five years of work experience;52.0%(37/71)of the laboratories used fully automated immunohistochemical staining equipment;57.8%(41/71)of laboratories adopted automated antigen retrieval for 20 minutes;46.5%(33/71)of laboratories included a biotin blocking step;54.9%(39/71)of laboratories set the DAB chromogenic time to 3-6 minutes;and multiple antibodies with different clone numbers were used for all four MMR markers.The statistical analysis of the results showed that there was a statistically significant difference in the staining qualification rates between antibodies of different clone numbers(P<0.05),while other factors had no significant correlation with the qualification rate(P>0.05).Conclusions This quality control activity reflects the overall level and key considerations of immunohistochemical operation in participating institutions.The overall qualification rate of MMR immunohistochemical staining is relatively high.It is recommended that each laboratory continue to use and optimize the validated,effective experimental protocols,further focus on experimental details,and promote the standardization and normalization of immunohistochemistry.