VARIATIONS IN EFFECTIVENESS OF ANTIGEN RETRIEVAL PRETREATMENTS FOR DIAGNOSTIC IMMUNOHISTOCHEMISTRY

Enzymatic and non-enzymatic pretreatments for antigen retrieval (AR) o n formalin-fixed, paraffin-embedded, deparaffinised sections were comp ared and optimised by immunostaining of tissues infected with 13 diffe rent pathogens. Enzymatic pretreatment was achieved by incubating slid es in 0.25 per cent trypsin (TR) and non-enzymatic pretreatments by he ating them in a microwave oven (MWO) or an autoclave (AC). Three diffe rent buffers of different pH and molarity including phosphate buffer ( PB), citrate buffer (CB) and acetate buffer (AB) were used as AR solut ions. All of them were effective regardless of molarity, for the MWO w ith a processing time of 20 minutes, and the Ac with a processing time of 15 minutes. The detectability of many viral antigens was significa ntly improved by MWO or TR pretreatment, but that of most bacterial an tigens was not improved and that of some viral antigens was decreased by TR pretreatment. These results suggest that AR pretreatment is a pr erequisite procedure for immunohistochemical detection of many infecti ous agents but the optimal pretreatment has to be individualised for e ach agent.