COMPARATIVE-ANALYSIS OF BIOTIN INTRANUCLEAR INCLUSIONS OF GESTATIONALENDOMETRIUM USING THE APAAP, ABC AND THE PAP IMMUNODETECTION SYSTEMS

Aims/background--Intranuclear inclusions have been observed in gestati onal endometrial glands. Although resembling Herpes simplex virus infe cted cells, these nuclei have been shown to contain endogenous biotin. Hence, immunohistochemical systems using the avidin-biotin complex wi ll result in cross reaction and false positivity. This study investiga tes a series of 10 gestational endometria (formalin fixed and paraffin wax embedded) with intranuclear inclusions using three different immu nodetection systems with primary anti-biotin. Results--Both the alkali ne phosphatase anti-alkaline phosphatase (APAAP) and peroxidase anti-p eroxidase (PAP) systems confirmed that the intranuclear inclusions wer e endogenous biotin. The streptavidin biotin complex (StreptABC) syste m produced a positive reaction in both test sections and controls (omi tting primary anti-biotin) in the presence of prior blocking with free avidin and biotin. In addition, aberrant immunoreactivity was observe d in adjacent nuclei/cytoplasm of endometrial glands and decidualised stroma in the negative control of the PAP system. This was subsequentl y eliminated using microwave pretreatment prior to immunohistochemistr y. Conclusion--The use of either the APAAP or FAP immunodetection syst ems (the latter with microwave pretreatment) is recommended for any im munohistochemical or non-isotopic in situ hybridisation investigation undertaken on gestational endometria.