IMMUNOFLUORESCENCE OF DE-PARAFFINIZED, TRYPSIN-TREATED RENAL TISSUES - PRESERVATION OF ANTIGENS AS AN ADJUNCT TO DIAGNOSIS OF DISEASE

Abstract

Formalin-fixed, deparaffinized and trypsin-treated (DTT) renal tissue sections were compared with frozen sections for detecting immune complex deposition. Both DTT and frozen sections from 52 renal biopsies were stained directly with fluorescein isothiocyanate-conjugated antihuman Ig[immunoglobulin]G, IgM, IgA, fibrinogen and C3. DTT sections alone were stained indirectly for [complement] C3 using a double conjugate technique. Antigen presence or absence on DTT section was accurately detected in 90% of biopsies for immunoglobulins and fibrinogen and in 75% for C3 when compared to frozen section. Antigen deposition was found in 21% of biopsies only on DTT sections (usually because frozen tissue lacked glomeruli). Frozen sections alone were treated with reagents of the fixation-embedding process and directly stained for IgM and C3 to determine antigen stability. Alkaline or neutral formalin pH helped maximize antigen preservation. DTT sections are a valuable tissue source for adjunctive diagnosis of renal disease.