A new monoclonal anti-CD3 epsilon antibody reactive on paraffin sections

We generated a new monoclonal antibody (MAb), F7.2.38, by immunizing mice w ith CD3 epsilon gamma delta /CD3 omega complexes purified from human T-cell s by OKT3 MAb-Sepharose affinity chromatography. Immunoprecipitation experi ments and Western blotting analysis showed that MAb F7.2.38 recognized the CD3 epsilon chain in CD3 epsilon cDNA-transfected FOX B-cells and in Variou s T-cell lines. Using flow cytometry on permeabilized or intact cells, the epitope was found to be located in the cytoplasmic tail of the CD3 epsilon chain. Immunohistochemical staining on paraffin-embedded sections showed th at the reactivity of MAb F7.2.38 was comparable to that of the commercially available anti-CD3 epsilon polyclonal antibody. Of the 52 well-characteriz ed T-cell lymphomas, 41 were positive for F7.2.38 (79%), whereas all 37 B-c ell lymphomas and 69 non-lymphoid tumors were unreactive. This new antiCD3 epsilon antibody would be particularly useful for phenotyping T-cell lympho mas on routinely processed paraffin-embedded tissue sections.