A new monoclonal anti-CD3epsilon antibody reactive on paraffin sections

We generated a new monoclonal antibody (MAb), F7.2.38, by immunizing mice with CD3varepsilongammadelta/CD3omega complexes purified from human T-cells by OKT3 MAb-Sepharose affinity chromatography. Immunoprecipitation experiments and Western blotting analysis showed that MAb F7.2.38 recognized the CD3varepsilon chain in CD3varepsilon cDNA-transfected FOX B-cells and in various T-cell lines. Using flow cytometry on permeabilized or intact cells, the epitope was found to be located in the cytoplasmic tail of the CD3varepsilon chain. Immunohistochemical staining on paraffin-embedded sections showed that the reactivity of MAb F7.2.38 was comparable to that of the commercially available anti-CD3varepsilon polyclonal antibody. Of the 52 well-characterized T-cell lymphomas, 41 were positive for F7. 2.38 (79%), whereas all 37 B-cell lymphomas and 69 non-lymphoid tumors were unreactive. This new anti-CD3varepsilon antibody would be particularly useful for phenotyping T-cell lymphomas on routinely processed paraffin-embedded tissue sections.