Long-term preservation of direct immunofluorescence staining in slides stored at room temperature

To determine whether reproducible results from direct immunofluorescent tis sue staining could be obtained after storing the slides at room temperature . We examined the original slides of 22 cases noted to be positive for dire ct immunofluorescence. Diagnoses include pemphigus, pemphigoid, lupus, derm atitis herpetiformis, lichen planus, and vasculitis. These specimens, initi ally evaluated during the period January 1997 to September 1998, were prepa red with a standard immunofluorescence staining technique, and then a perma nent aqueous mounting medium was added. AU specimens were stored at room te mperature in vertical slide holding trays. We focused on the presence and r elative intensity of the immunofluorescence staining, as well as the final diagnosis. We then compared our readings to that of the original reports. T wenty of the 22 cases studied (91%) were read as hating the same diagnosis as the initial immunopathology report. Seventeen of the 22 cases (77%) were found to have the identical or slightly less fluorescence intensity. The o riginal reports in 3 of the cases did not comment on the original intensity of fluorescence. Thus, a comparison of fluorescence preservation could not be made. In 2 of the cases, the quality of tissue preservation was poor, a nd though fluorescent staining was noted, we were unable to render a diagno sis. Our results suggest that direct immunofluorescent studies, using a per manent aqueous mounting medium, can be stored over long periods of time at room temperature without significant degradation of staining.