Pervez, S

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eCommons@AKU

eCommons@AKUDepartment of Pathology and Laboratory Medicine Medical College, PakistanMarch 1995Microwave oven--not only for cookingS PervezAga Khan University, shahid.pervez@aku.eduFollow this and additional works at: https://ecommons.aku.edu/pakistan_fhs_mc_pathol_microbiolPart of the Microbiology Commons, and the Pathology CommonsRecommended CitationPervez, S. (1995). Microwave oven--not only for cooking. Journal of Pakistan Medical Association, 45(3), 76-77.Available at: https://ecommons.aku.edu/pakistan_fhs_mc_pathol_microbiol/918Microwave Oven - Not Only for CookingPages with reference to book, From 76 To 77 Shahid Pervez ( Dept of Pathology, Aga Khan University Hospital, Karachi. ) One of the major technical advances in the field of histopathology during the last decade is thedevelopment of immuno-histochemical (ll{C) techniques1,2. Growing demand of antibodies that can beused for IHC on routine formalin fixed paraffin embedded tissues has stimulated efforts to developantibodies that can recognize formalin-resistant epitopes. Alternatively, it is desirable to devisestrategies to unmask cross-linked antigenic sites. One popular approach is to treat the sections withaprotease such as trypsin or pronase before immunostaining. It is thought that the protease treatmentbreaks the cross-linking bonds of the fixative with the protein to reveal the antigemc sites. In ourexperience, this is helpful with only a handful of antibodies like cytokeratins. Our repeated full-heartedattempts to retrieve estrogen receptor antigenic sites with this method failed3. Clearly this means thatthe capability of retrieval of masked epitopes could not only significantly expand the range ofantibodies useful in immunohistochemistry, but also reduce the incidence of false negative staining inover-fixed tissues, which is a frequent happening in our setting. With these goals and problems in mind,repeatedly failing with trypsin digestion technique and inspired with some other studies4,5, the effectsof microwave heating were tried for retrieval of estrogen receptor antigenic sites on fixed material. We:round a dramatic enhancing effect of this treatment for unmasking estrogen receptor antigen and nowroutinely using it. In our setting as most of the breast tumours which are received for estrogen receptordetennination are already formalin fixed. With conventional techniques, chances of false negativity arevery high and in our opinion, this can only be circumvented by microwave digestion. For this purpose,we place de-parafinnized tissue sections in a plastic jar filled with 10 mM citrate buffer at pH 6.0. Thenthese sections are incubated in a microwave oven (buffer has to boil) six times for 5 minutes each,giving annse in between. Domestic microwave ovens can be used forthese applications with somereservations. For instance, heat distribution may not be uniform. The H2200 staining microwaveprocessor (Energy Beam Sciences, P.O. Box 468, Agawarn, MAO 1001, USA) is specifically designedfor histopathology and provides accurate time and temperature control6. For quality control puiposewith reference to estrogen receptordetermination, we choose tumour blocks which also contain normalbreast lobules and are hesitant of calling any tumour negative if these breast lobules (built in control arenegative. Although the mechanism concerning microwave oven recovery of antigens is not clear, it ispossible that the cross-linking of proteins caused by formaldehyde may be altered by microwaveheating. We believe that a microwave oven in a laboratory means improved patient care.Acknowledgement I am grateful to Ms Amina Anwer Ali for her secretarial assistance.References 1. Pervez, S., Ahmed, R.. Aijaz, F. et al. Application of immunocytochemistry in the differentialdiagnosis of undifferentiated tumours and lymphoproliferative disorders. PJR 1993;4:87-93.2. Pervez, S. Immunohistochemistry in tumour diagnosis - Who actually needs it? J. Pak. Med. Assoc..1994;44:199.3. Pervez, S., Shaikh. H.. Aijaz, F. et al. Immunohistochemical estrogen receptor determination inhuman breast carcinoma: Correlation with histologic differentiation and age of the patients. J.Pak. Med.Assoc., 1994;44: 133-36.4. Shi, SR.. Key, M.E. and Kalra. K.L. Antigen retrieval fixed paraffin-embedded tissues: Anenhancement method for immunohistochemical staining based on microwave oven heating of tissuesections. 3. Histochem. Cytochem., 1991 ;39:741-48.5. Cattoretti, G., Pileri, S.. Parravicini, C. et al. Antigen unmasking on formalin. fixed, paraffinembedded tissue section. 3. Pathol., 1993; 171:83-98.6. Fox, C.H., Johnson, F.B., Whiting, J. et al. Formaldehy de fixation. J. Histochem. Cytochem..1985;33 :845-53.

Microwave oven--not only for cooking

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Microwave oven--not only for cooking

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