Heat-induced antigen retrieval by using Tris-EDTA solution destroys nuclear structure in certain tissues.

Tris-EDTA buffer (pH 9.0) is widely used for heat-induced antigen retrieval (HIAR) in immunohistochemistry due to its high efficiency. However, it remains unclear whether Tris-EDTA is equally suitable for all tissues and for the detection of both nuclear and non-nuclear antigens. In this study, we systematically evaluated the effects of Tris-EDTA HIAR on mouse and human tissues. Nuclear morphology was assessed by DAPI and hematoxylin staining, while immunohistochemistry and immunofluorescence were used to detect nuclear and non-nuclear antigens. We found that Tris-EDTA HIAR caused selective nuclear disruption (nuclear content leakage) in thyroid, lung, and kidney tissues, manifested as weak or abnormal staining. Consequently, nuclear antigens in these tissues showed poor detection, including weak signals, mislocalization, or complete loss. In contrast, nuclear antigen detection was preserved when citrate buffer (pH 6.0) was used. For non-nuclear antigens, however, Tris-EDTA HIAR generally produced stronger staining than citrate buffer. Although nuclear content leakage may lead to slightly higher background, Tris-EDTA HIAR did not appear to damage the antigens themselves. In addition, both the pH and the antigen retrieval method influence the nuclear morphology in Tris-EDTA-treated sensitive tissues. In conclusion, Tris-EDTA HIAR should be used with caution for nuclear antigen detection in thyroid, lung, and kidney tissues but remains effective for non-nuclear antigens. These findings provide practical guidance for optimizing antigen retrieval strategies in both clinical diagnostics and research.