Immunocytochemistry is a method that uses monoclonal or polyclonal antibodies to detect antigens in cell samples. In the field of oncological pathology and cytopathology, it has become an indispensable adjunctive method for the identification of the origin of malignant neoplasms. The binding of the primary antibody to the antigen can be visualised using different detection systems, such as iView DAB, OptiView DAB and EnVision FLEX. Automated stainers, used for immunocytochemical staining, have the advantages of performing more time-consuming steps of the procedure and improving the reproducibility of the reactions. Standardisation of immunocytochemical stains is challenging due to differences in sample preparation and fixation as well as in the reagents and stainers used. Therefore, it is essential that every cytopathology laboratory optimises and verifies staining procedures with appropriate testing prior to use in routine diagnostics.
In the framework of this master’s thesis, we optimised immunocytochemical staining protocols for 10 tumour markers (calretinin, BER-EP4, MOC-31, CK AE1/AE3, CD68, CK 5/6, LCA, desmin, HBME-1 and WT1) using new detection systems OptiView DAB and EnVision FLEX. The results of the evaluation criteria of reaction percentage and intensity, background, contrast, and morphology were compared with the results of staining with the iView DAB detection system, which is currently routinely used at the Institute of Oncology Ljubljana but is being withdrawn from sale. The selected protocols were tested on 10 positive and 10 negative cytological samples for every tumour marker.
After evaluation of the stained slides, we concluded that all selected protocols with OptiView DAB and EnVision FLEX are suitable for routine diagnostic use. The results were comparable or even better for detection of calretinin, BER-EP4, MOC-31, CK AE1/AE3, CK 5/6 and WT1 when compared to the iView DAB protocols. To achieve better results, protocols with OptiView DAB would be prioritised for desmin and WT1 detection over EnVision FLEX. For detection of calretinin, BER-EP4, MOC-31, CK AE1/AE3 and CK 5/6 with OptiView DAB protocols, the background was avoided by pretreatment with CC1 solution, and the appropriate intensity was achieved by the additional step of signal amplification. Attention should be paid to non-specific staining of cell nuclei for EnVision FLEX protocols without pretreatment and to non-specific staining of erythrocytes for protocols with high pH pretreatment. Agreement between assessors' scores and testing of sufficient number of cytological samples are also crucial for a reliable and quality diagnosis.
|