Adoptive transfer of IL-10−/− B cells was capable of rescuing tumor growth in BCDM inoculated with KrasG12D to the same extent as WT B cells, however tumor growth remained suppressed with adoptive transfer of IL-12α−/− B cells, indicating that promotion of tumor growth by infiltrating CD1dhiCD5+ B cells in this PDAC model is mediated by IL-35, a heterodimer comprised of p35 and EBI3 subunits encoded by the genes IL12α and EBI3, respectively. Here, EBI3 is linked to neoplasm.