FCGR2B and neoplasm: Because the cell-autonomous ability of FcγRIIB to regulate tumor-infiltrating CD8+ T cell responses has never been tested, we generated TCR-transgenic, antigen-specific OT-I T cells that were deficient in Fcgr2b. Thy1.1+ WT or Fcgr2b–/– OT-I T cells were adoptively transferred into naive CD45.1+ congenic recipients 24 hours prior to inoculation with B16-OVA melanoma cells (Figure 4A).