Parent phenotype and age dependence, on rat glioma tumor rejection.

Background: The brain, despite the blood-brain barrier, does not escape to the highly variable host rejection response mediated by a very strong and complex immune reaction when rat glioma cells are transplanted into the adult animal.

Methods: Crosses were performed among parents that are able or enable to reject a well-known brain tumor cell line (C6). Newborn animals were also challenged with rat glioma cells both in the brain and the side flanks.

Results: The percentage of susceptibility or resistance to develop a lethal glioma can be estimated knowing the parental phenotypes. When both parents had rejected an induced tumor, 63% of the progeny will also reject it. Similarly, if both parents died as a consequence of the tumor, 70% of the progeny would also be unable to reject the challenge of glioma C6 cells. Newborn animals do not have a mature immune system and they tolerate transplanted cells much better than adults. We found no rejection to glioma C6, at both brain and side flank sites, in 1-day-old neonatal Wistar rats. Tumors were beginning to be eliminated if the cells are inoculated at day 3 from birth on the flanks, and at 1 week from birth on the brain.

Conclusions: There is a genetic component conferring susceptibility or resistance to the lethal effect of tumor development and progression depending on the parental phenotype of the adult rats. Neonatal rats represent a much more reliable model than adults to study experimental therapies against gliomas.