CD4 and neoplasm: Consistent with in vitro data, there was a reduction in the proportion of tumor-infiltrating Treg cells in mice treated with the IgG1 mAb (mean percentage of Treg/total CD4+ T cells = 24%) compared with those treated with the IgG1N297A variant (Treg/total CD4+ T cells = 37%) or with control mice (Treg/total CD4+ T cells = 44%, p <0.001).