Expression of a restrictive receptor for interleukin 13 is associated withglial transformation

We have previously documented that the vast majority of high-grade gliomas over-express binding sites for interleukin 13 (IL13) in situ. We now extend this analysis to evaluate the distribution of the binding of IL13 among ot her brain tumors. Tumor specimens from patients with low-grade gliomas, oli godendrogliomas, ependymomas, pilocytic astrocytomas, gliosarcomas, medullo blastomas, meningiomas, and metastases to the brain were analyzed and compa red to a new series of gioblastoma multiforme (GBM) samples. Serial tumor t issue sections were incubated with I-125-labeled (i) IL13, (ii) antibody ag ainst transferrin (Tf) receptor, and (iii) epidermal growth factor (EGF). M ost (17/18) GBMs stained specifically for IL13 binding sites while sections from 3/11 low-grade gliomas, 5/5 high-grade gliomas (grade III), 3/5 oligo dendrogliomas (all three were anaplastic), and 1/2 gliosarcomas also showed specific binding for IL13. We did not detect IL13 binding sites in medullo blastomas (0/4) and found them only in 2/20 meningiomas. Metastases to the brain (4/12, i.e., lung adenocarcinomas and renal cell carcinoma) showed so me binding of I-125-IL13. The presence of receptors for Tf was ubiquitous a mong all studied tumors while EGF receptor expression was much more variabl e. Since it appears that primarily the least differentiated forms of glioma s possess IL13 binding sites in abundance, it is plausible that IL13 recept or expressed in low-grade gliomas might be a prognostically significant mar ker associated with their progression to high-grade gliomas. Finally, we de monstrate that the glioma-associated IL13 receptor is truly more restrictiv e in nature also due to its selective representation among brain tumors of glial origin.