The effects of fixation time in buffered formaline at 10% on different methods of antigenic site retrieval induced by heat (HIER) for the detection of the expression of antibodies anti-PCNA (nuclear proliferation antigen) and anti-AE1 and AE3 (citokeratins) were studied. Specimens with cross section of 0,5 cm² from five Tonsils from ellective tonsillectomies done at Hospital São Paulo UNIFESP/EPM were fixed for six, 12, 18, 24 and 48 hours and embedded in paraffin for the production of 4mum sections. For HIER was used a steamer, microwave oven and pressure cooker. The level of PCNA expression was assessed by the ratio stained nuclei: total number of nuclei. The staining intensity was assessed by using Corel Photo Paint 9 and UT Morph 2.0 softwares. The present study has shown that: 1) for the detection of anti-PCNA, the use of a microwave oven provided the best results; 2) for the detection of anti-PCNA, longer fixation periods, specially after 24 hours, causes the staining intensity to decrease; 3) for the detection of AE1 and AE3, all procedures used provided equivalent levels of staining.
Imunohistochemistry; Antigen retrieval; Fixation methods
