1. Due to the lack of a standardized system for evaluating the immunodeficiency, an objective choice of the appropriate immunodeficient mouse strains to be used for tumor engrafting experiments is difficult.
2. We developed a tumor engraftment index (TEI) to quantify the immunodeficiency.
3. 1) TEI helps researcher choose an appropriate immunodeficient mouse strain for tumor engrafting experiments.
2) TEI provides a platform to compare the immunodeficiency of a new mouse strain with the well-established immunodeifient mouse strains.