ESTROGEN-RECEPTOR IMMUNOHISTOCHEMISTRY IN FORMALIN-FIXED, PARAFFIN-EMBEDDED BREAST-TUMOR TISSUE - ENHANCED SENSITIVITY USING A MONOCLONAL ANTIBODY COCKTAIL
Gr. Ibarra et al., ESTROGEN-RECEPTOR IMMUNOHISTOCHEMISTRY IN FORMALIN-FIXED, PARAFFIN-EMBEDDED BREAST-TUMOR TISSUE - ENHANCED SENSITIVITY USING A MONOCLONAL ANTIBODY COCKTAIL, Applied immunohistochemistry, 3(3), 1995, pp. 202-208
To investigate whether the immunohistochemical estrogen receptor (ER)
assay could be improved with the use of a cocktail of anti-ER monoclon
al antibodies (clones 1D5 and LH1), we compared such a cocktail with e
ach of its constituent antibodies acting alone, on formalin-fixed, par
affin-embedded sections from 56 cases of breast carcinoma and with the
Abbott ER-ICA acting on frozen sections from the same tissues. The la
tter was considered to be the standard reference in this study. With a
90 min fixation, the cocktail showed enhanced reactivity over that of
single antibodies, exhibiting a 98% sensitivity and 100% specificity
when compared with the reference ER-ICA assay (sensitivity designated
100%). In addition, the effect of overfixation on the immunoreactivity
of the cocktail and of the single antibodies was evaluated in tissues
fixed for 1, 3, or 7 days. Overfixed tissues exhibited diminished rea
ctivity with all antibodies. The ER-cocktail, ER-IDS and ER-LH1 showed
a 20, 26, and 35% reduction in reactivity, respectively, with the lon
ger fixation time. When more vigorous epitope retrieval methods were u
sed, ER-cocktail reactivity was almost completely recovered (to 97%),
while the reactivities ER-1D5 and ER-LH1 were recovered to lesser exte
nts (87 and 81%, respectively), We found that the ER-cocktail produced
the highest specific nuclear staining with no increased background st
aining. We conclude that an ER-cocktail as used in these studies could
, to advantage, replace the single antibodies currently used for ER im
munohistochemical assays.