To determine whether CD3+ T cells are required for the acquisition of an OPG-producing regulatory phenotype, we first quantified OPG secretion by CD19+ B cells isolated from the iliac BM of 67NR tumor–bearing wild-type BALB/c (B 67NR) and T cell–deficient nude BALB/c (B Nude 67NR) mice 11 days after tumor implantation (Fig. 4E and F). Here, CD19 is linked to neoplasm.