PSEUDO-IMMUNOLABELING WITH THE AVIDIN-BIOTIN-PEROXIDASE COMPLEX (ABC)DUE TO THE PRESENCE OF ENDOGENOUS BIOTIN IN RETINAL MULLER CELLS OF GOLDFISH AND SALAMANDER

Immunodetection techniques are dependent on enzyme-protein conjugates for the visualisation of antigen-antibody complexes. One of the most w idely used is the avidin-biotin-peroxidase complex (ABC) method. The p resent study demonstrates that direct treatment of goldfish and salama nder retinal sections with ABC, followed by an incubation with the chr omogenic substrate 3,3-diaminobenzidine tetrahydrochloride (DAB) and H 2O2, manifested a punctate staining pattern across the neural retinae, presumably through binding of avidin to endogenous biotin. Incubation with a primary antiserum against biotin followed by immunoprocessing with the peroxidase-anti-peroxidase (PAP) method showed a pattern simi lar to the punctuate framework as detected with solo ABC-treated secti ons. Moreover, the ABC-DAB/H2O2 mediated pattern corresponded to the s patial orientation of Muller cells as identified by GFAP immunostainin g. These findings indicate the presence of endogenous biotin in Muller cells and calls for caution in the application of the ABC method in i mmunotechniques in retinal research. (C) 1997 Elsevier Science B.V.