Multiple immunofluorescence labeling of the same section of invasive ductal breast cancer: A preliminary study

The expression of candidate genes in tissue samples were investigated by using immunohistochemical study of formalin-fixed paraffin-embedded (FFPE) tissue or immunofluorescence labeling of cryosections. However, the study of co-localization of multiple antigens in the same section by immunohistochemical labeling is difficult to evaluate and involves antigen retrieval step to unmask antigen whereas immunofluorescence labeling has the capability for multiple labeling with higher resolution. Nevertheless, the handling of fresh tissue as immunofluorescence labeling is difficult. Thus, both methods have limitations as research tools. In this study, we optimized an antigen retrieval method for high-resolution immunofluorescence labeling of FFPE invasive breast cancers using three different biomarkers (Ki-67, Her-2 protein and E-cadherin). Citraconic anhydride solution at 0.05 % pH 7.4 in a microwave oven seemed to work well for multiple antibodies for co-localization of multiple antigens in the same section. In addition, this method is suitable for core needle biopsy which obtained small amount of tissue. Therefore, it is not enough for preparation of multiple sections.