Validation of nominally expired antibodies for immunohistochemistry.

The Histopathology Department at the Children's Hospital at Westmead has 114 antibodies in its Immunohistochemistry panel; 64 of these are purchased as concentrates and usually have expiration dates 1-2 years after receipt by the laboratory. To replace these antibodies after expiration would require approximately $40,000/year. It has been reported that continued use of these reagents beyond their expiration dates may be feasible. I used the iPassport quality management system to track antibody expiration dates and verified extended fit-for-purpose for these reagents. iPassport is web-based quality management software that assists medical laboratories with document control and quality management. Review of the records since the inception of iPassport in 2015 indicates no failed verifications and to date, the average life after expiration is 6 years; eight antibodies have exceeded 6 years. Some antibodies with exceptionally extended lifespans include factor 8 (21 years), factor 13a (19 years) and epithelial membrane antigen (17 years). Selecting antibodies to be discarded should be based on performance rather than expiration date alone. The iPassport quality management system has enabled permanent recording and periodic validation of nominally expired antibodies.

Aberrant Cytoplasmic Terminal Deoxynucleotidyl Transferase (TdT) Immunostaining on Previously Frozen, Formalin-fixed Paraffin-embedded Tissue: Cryotomy-induced Antigen Diffusion (CIAD).

Terminal deoxynucleotidyl transferase (TdT) has been localized in both the nuclear and cytoplasmic compartments of lymphoblastic lymphomas when such tumors have been frozen for cryotomy and subsequently, formalin fixed and processed to paraffin. This cryotomy-induced antigen diffusion (CIAD) occurs with several different sources of anti-TdT antisera and was not observed in nonlymphoblastic tumors. CIAD was also not observed with other nuclear antigens including BRG1, Pax5, Ki67, BCL6, INI-1, myogenin, MyoD1, and Phox2B. TdT CIAD seems to be specific for lymphoblastic lymphomas. CIAD is another preanalytical artifact that needs to be considered in immunohistochemistry.

Coronavirus disinfection in histopathology.

The 2019 Coronavirus epidemic, provisionally called 2019-nCoV, was first identified in Wuhan, China, in persons exposed to a seafood or wet market. There is an international push to contain the virus and prevent its spread. It is feasible that potentially infectious samples may be received in histopathology laboratories for diagnosis. This technical note presents disinfection procedures and histotechnology processes that should alleviate the risk of infection to laboratory staff. Using data obtained from similar coronaviruses, e.g. severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), experts are confident that 70% ethanol and 0.1% sodium hypochlorite should inactivate the virus. Formalin fixation and heating samples to 56oC, as used in routine tissue processing, were found to inactivate several coronaviruses and it is believed that 2019-nCoV would be similarly affected.