Dietary Vitamin D₃ Restriction Influences Tumor Growth, but not the Ability to Generate an Antigen-Specific Immune Response in OTII Transgenic Mice

Abstract

Initially, we wanted to know whether dietary vitamin D₃ restriction would influence growth and metastasis of the 4T1 murine mammary carcinoma. We confirmed serum 25(OH)D levels were modulated by dietary vitamin D₃ restriction, mice were healthy, and when challenged with the 4T1 tumor alterations in tumor growth, but not metastasis were evident. Tumors grew more rapidly in mice on the vitamin D₃ restricted diet. To delineate whether dietary vitamin D₃ restriction influenced the ability to generate an antigen-specific immune response we used OTII transgenic mice which express a T cell receptor specific for ovalbumin. We found that dietary vitamin D₃ restriction did not influence the health of OTII mice, the number of circulating CD3/CD4⁺, CD3/CD8⁺, CD4/CD25⁺ T cells, nor the ability to generate CD11c⁺ bone-marrow derived dendritic cells. T cells from OTII mice maintained on the vitamin D₃ restricted diet also exhibited no significant alterations in proliferative capacity or ability to secrete IFN-γ or IL-4 in an antigen-specific manner. Yet, EL-4 tumors grew more rapidly in OTII mice on the vitamin D₃ restricted diet. These data show that dietary vitamin D₃ restriction impacts tumor growth, but not the ability to generate an antigen-specific immune response.

Keywords:

• Vitamin D
• Breast cancer
• OTII mice
• Immune responsiveness