Prevalence of Leukocyte Chemotactic Factor-2 (LECT-2) in Renal Amyloidosis
Sanjeev Sethi, Agnes B Fogo, Paisit Paueksakon. Mayo Clinic, Rochester, MN; Vanderbilt University, Nashville, TN
Background: The type of amyloid whether AL, AA, hereditary or other has major impact on therapy. Amyloidosis may be identified by renal biopsy, but in some cases without definitive protein subtypes is not determined by standard immunofluorescence or immunohistochemistry. Recently, leukocyte chemotactic factor-2 (LECT-2)-associated amyloid has been described. We investigated the prevalence of this amyloid type contributing to previously unclassified cases.
Design: Forty-seven renal amyloidosis cases with available paraffin blocks in our 2002-2011 renal biopsy files at VUMC, were reviewed. Patients were designated as a classified amyloid (AA and AL) or a non-classified (absence of monoclonal staining pattern for kappa and lambda by IF and negative amyloid-associated protein IHC). IHC with LECT-2 specific antibody was performed. Mass spectrometry was performed in 8 patients.
Results: 43 patients had amyloid classified as either AL (42) or AA (1). These patients ranged from 33 to 84 years old (mean 62.1± 2.0) (pNS vs. non-classified), male/female ratio 1.8 and white/black ratio 9.8. Four patients had non-classified amyloid. These patients were 51 to 74 years old (mean 65.5±5.0), all males, and white/black ratio 3. Proteinuria was not significantly different (the non-classified 3.0 ± 1.0 g/24 h vs. 6.4± 0.7 in AA/AL). Two of 4 patients in the non-classified group were identified as amyloid LECT-2 by IHC and of these, LECT-2 was also identified by mass spectrometry in 1 patient. Two of 4 patients in the non-classified group were negative for LECT-2, however, the mass spectrometry showed apolipoprotein IV as a major protein component. Four of 43 AL amyloid patients showed positive LECT-2 IHC in glomeruli and arteries. However, LECT-2 was not identified by mass spectrometry in any of these 4 cases. The single patient with AA amyloid was negative for LECT-2 by IHC.
Conclusions: In summary, among 4 unclassified amyloidosis patients in our study, 2 had LECT-2 and 2 had apolipoprotein IV as a major protein component. Four AL patients also had LECT-2 as a minor protein component by IHC. Whether LECT-2 plays a pathogenic role in the amyloidogenesis in these AL patients will require further investigation. We conclude that positive IHC for LECT-2 may not be specific to determine amyloid type. Further, cases of unclassified amyloid by standard testing may include LECT-2 amyloidosis.
Category: Kidney (does not include tumors)
Wednesday, March 21, 2012 1:00 PM
Poster Session VI # 287, Wednesday Afternoon