Interactions between EGF-SEA and EGFRs expressed by S180 carcinomas.

<p>(A) EGF-reactive S180 tumor cells and SEA-reactive T cells. Sections were incubated with an EGF-SEA solution, followed by mouse polyclonal anti-SEA IgG fraction and anti-mouse secondary antibody. Anti-SEA antibodies were able to react with EGF-SEA on the surface of S180 tumor cells and T lymphocytes (small brown spots in the section treated with EGF-SEA). (B) Detection of phospho-EGFR (Y 1068) in S180 cells. Sections were labeled with mouse phospho-EGFR-specific monoclonal antibody (Y 1068). Phosphorylated EGFR molecules were found in the tumors treated with EGF-SEA and SEA (red arrows). (C) An immunohistochemistry control. A tumor section from the EGF-SEA treated group was labeled with goat anti-mouse secondary antibody only. (D) Analysis of LSS670-labeled EGF-SEA binding to S180 cells by FACS analysis. S180 cells (2×10⁶) were incubated with 125.00, 12.50 and 1.25 pmol of LSS670-labeled EGF-SEA proteins and PBS (control). Microscope magnification: ×400 in A to C.