Introduction There are past indications that the adaptive immune response of B cells plays a role in tumor development. We examined this issue in vivo by examining the growth of Lewis Lung Carcinoma (LLC) and murine melanoma in B cell knockout (Bcell ko) mice. Methods Cultured LLC or melanoma cells were implanted into hindlimbs of C57BL/6 (B6) and Bcell ko mice. Tumors were measured every 3-4 days, and tissue was harvested for histological examination 2-3 weeks after tumor implantation. Tissues were stained with labeled anti-IgG, -CD4, -CD8, and -CD31 antibody. Results Melanomas in B6 and B cell ko mice enlarged at the same rate. However, tumor growth of LLC was significantly slower in B cell KO mice compared to B6 (p=0.02). Though both tumor-infiltrating CD4+ T cells and CD8+ T cells were identified in B6 mice, tumor-infiltrating CD4+ T cells but no tumor-infiltrating CD8+ T cells were seen in B cell KO mice in LLC. Angiogenesis was significantly inhibited in LLC in B cell KO mice. Conclusions The absence of B cells selectively inhibited tumor growth for LLC, and was associated with less tumor angiogenesis and an absence of CD8+ T cells. Blocking this aspect of the B cell response might be useful therapy for selected tumors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3532. doi:1538-7445.AM2012-3532