GZMB and Hodgkins lymphoma: In order to avoid inducing de novo granzyme B expression during suppression assays in Tregs previously expanded in rapamycin, and to separate the suppressive and cytotoxic function of Tregs, we developed a flow cytometry based cytotoxicity assay using a Hodgkin lymphoma cell line (L428) that we had previously observed to be susceptible to in vitro Treg-mediated cytotoxicity (unpublished observation).