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.