Immunofluorescent (IF) Slides for Renal Biopsies Can Be Safely Used for Review after One and Half Years of Storage in Room Temperature.
Thomas R Fennell, Michelle T Rooney, Ping L Zhang. William Beaumont Hospital, Royal Oak, MI
Background: IF sections for renal biopsies are usually discarded after the diagnosis is reached in many laboratories because of assumed reduced fluorescent intensity over time. IF slides are ideally used for later internal and external reviews in addition to slides for light (LM) and electron microscopy (EM). In this quality control study, we determined whether IF staining intensity was reduced in renal biopsies over one and half years.
Design: We retrospectively queried our database for control cases composed of 21 focal segmental glomerulosclerosis (FSGS) and 35 study cases with immune complex mediated glomerulopathy (ICMG), from 01/2009 to 06/2010. The frozen sections were washed with Difco FA buffer, incubated with specific fluorescein labeled antibodies for 30 min and coverslipped with Permafluor mounting media. IF slides were kept in dark boxes at room temperature after initial evaluation. IF slides for IgG, kappa and lambda were re-examined for fluorescent intensity after a storage time ranging from 1 to 17.5 months (m) and the fluorescent intensity was scored from 0 to 3+. The re-examined scores were compared with initial scores statistically.
Results: Control cases (FSGS) showed no staining in both initial and re-examination. In ICMG group, there was small but non-significant reduction in staining intensity for IgG, kappa and lambda over time; these included 1.3% reduction from 1m to 6 m (n = 13), 10.0 % reduction from 6 m to 12 m (n =10) and 8.3% reduction from 12 m to 17 m (n = 12). Overall (including control and study cases, n = 56), there was significant correlation between initial scores and re-examination scores (IgG, r = 0.924, p = 0.001; kappa, r = 0.878, p = 0.001; lambda, r = 0.879, p = 0.001, by linear regression analysis). One case with remarkable intensity reduction at 14 m was a type 2 lupus nephritis. One anti-glomerular basement membrane (GBM) case did not show intensity reduction at 5 m but another anti-GBM case lost most of staining intensity at 13.5 m.
Conclusions: Our data suggest that IF intensity, corresponding to large immune complex deposits by EM, was relatively well maintained from 1 month to 17.5 m in most cases, particularly when a panel of stains (such as IgG, kappa and lambda) was reviewed and a trend of panel staining was considered together. Small deposits in mesangial areas and anti-GBM staining may be lost after a year. Room temperature is adequate for the storage. This study encourages complete internal or external reviews using all LM, IF and EM slides in each renal biopsy case.
Category: Quality Assurance
Monday, February 28, 2011 1:00 PM
Poster Session II # 218, Monday Afternoon