Receptor for interleukin 13 is abundantly and specifically over-expressed in patients with glioblastoma multiforme

We have recently documented that the vast majority of patients with gliobla stoma multiforme (GBM) over-express a receptor (R) for interleukin 13 (IL13 ) in situ. We have now evaluated further the degree of relative specificity of the binding of IL13 to GEM when compared with other growth factor recep tors. Tumor samples of 11 patients with CEM, 7 various normal brain samples , and several cell lines in culture were examined. Same patient tissue sect ions were incubated with I-125-labeled: IL13, monoclonal antibody HB21 agai nst human transferrin (Tf) receptor, epidermal growth factor (EGF), and an IL4 antagonist, IL4.Y124D. All 11 GBMs stained specifically, densely, and r elatively homogeneously for both IL13R and TW. Seven GEM specimens showed s pecific binding for I-125-EGF, but it was less homogeneous when compared wi th IL13R or TfR. Two of the GBMs studied demonstrated extremely high densit y of the EGFR. Furthermore, we did not detect significant presence of the I L4R in the studied GEM specimens in situ. All sections of nonmalignant brai n tissues examined showed avid binding by the TfR with lack of consistent a nd specific binding of I-125-IL13 or -EGF. Thus, it appears that the GEM-as sociated IL13R is considerably more specific to GEM that the one for Tf and more frequently and homogeneously expressed than the EGFR. These results r ender further support for the hIL13R being a new unique candidate for deliv ery of variety of anti-GBM therapies.