Durability of direct immunofluorescence (DIF) slides stored at room temperature.

Abstract

Prior studies suggested that direct immunofluorescence (DIF) slides can be stored at room temperature. We sought to determine the durability of DIF slides stored at room temperature for 5 years. This was a retrospective study of 83 DIF slides archived at room temperature during 2010. The pattern of immunoreactants was compared with those noted in the original report. Loss of reactivity was limited to cases with weak fluorescence at original diagnosis. Loss of IgG was noted in 12.5% of cases, IgA in 12%, C3 in 10%, and IgM in 9.75%. Fibrin showed no loss of reactivity. Preservation of immunofluorescence was not related to site of deposition. Overall, a reliable diagnosis could be made in 75 of 79 archived cases (94.9%). Cases had been archived for periods varying from 4.5 to 5 years. Variations in processing and fluorochromes could affect durability. We have no way of knowing how long slides had been exposed to ultraviolet light at the time of initial examination. DIF showed excellent durability in slides kept at room temperature for 5 years.