Zenobia Haffajee | Search PubMed

PubMed2006

Refinement of immunohistologic parameters for Her2/neu scoring validation by FISH and CISH.

The conventional method of scoring Her2/neu immunostaining is recognized to result in a high false-positive rate among 2+ cases when compared with results obtained with fluorescence in situ hybridization (FISH); however, costs and convenience dictates that immunohistochemistry remains the screening test for Her2/neu status in patients with breast cancer. We describe refined criteria for scoring of Her2/neu on the basis of anatomic localization rather than the subjective assessment of intensity. The presence of a circumferential tram track pattern that results from the staining of apposing cell membranes in >25% of the tumor cells was necessary for a 3+ score (Her2/neu overexpressed) and the presence of the tram track pattern in <25% was scored 2+ (equivocal); granular and fragmented membrane staining was scored 1+ (negative). The tram track pattern of Her2/neu overexpression showed 100% concordance with gene amplification. FISH and CISH testing in selected cases from the other categories validated the revised scoring method. These criteria reduced the numbers of equivocal staining cases that required FISH testing.

Biomarkers, Tumor↗

PubMed2002

Superheating antigen retrieval.

Heat-induced antigen retrieval in a variety of solutions has been shown to enhance the immunoreactivity of a wide range of antigens in routine formalin-fixed, paraffin-embedded tissues. Accurate time and temperature control is important for standardization and optimization of the procedure but is difficult to achieve. This study used a device to attain precise time and temperature control for antigen retrieval at 120 degrees C under 1.9 bar pressure. It compares the efficacy of this method with antigen retrieval in a conventional pressure cooker, by microwave heating at 98 degrees C, and ultrasound retrieval at 40 and 70 W for 40 and 100 seconds. Multitissue and multitumor blocks containing a spectrum of normal tissues and a variety of tumors, respectively, were used, and 42 routine diagnostic antibodies were applied with a standard peroxidase conjugated streptavidin technique. Sections in which antigen retrieval was not performed served as controls. The three heat-induced methods showed distinctly better immunostaining for all antigens compared with those obtained with ultrasound retrieval. The latter method did not produce consistent staining and intensity, and the extent of staining was only marginally better than sections not subjected to antigen retrieval. Superheating at 120 degrees C produced the best overall results with the exception of antibodies to cytokeratin clones Cam 5.2, AE1/3, and 34BE12 in which superheating resulted in slightly inferior immunostaining compared with heating in a pressure cooker and at 98 degrees C.

Antigens↗