MONOCLONAL-ANTIBODY AGAINST THE FUSION JUNCTION OF A DELETION-MUTANT EPIDERMAL GROWTH-FACTOR RECEPTOR

A mouse monoclonal antibody (IgG2b), 3C10, was produced against the tr uncated epidermal growth factor receptor (EGFR), encoded by the (type III) in-frame deletion mutation of 801 nucleotides of EGFR affecting t he external domain, known to be expressed in some human glioblastoma. As this mutation newly generates a glycine residue at the fusion point , a 14 amino acid peptide around the fusion junction including this gl ycine was chemically synthesised and used for immunisation of (B6 x DB A/2) F1 mice. Flow cytometric analysis showed 3C10 antibody staining o f a mouse NIH:3T3 transfectant (ERM5) with the type III EGFR deletion- mutant gene, but not one with wild-type EGFR. The antibody immunopreci pitated the truncated EGFR protein with a molecular mass of approximat ely 140 kDa from ERM5 cells. Immunostaining of glioblastomas revealed binding in the case with the type III EGFR mutation, the five other sp ecimens without the mutation being negative despite overexpression of EGFR in some cases.