Immune cell phenotype and cytokine secretion in mouse breast cancer responding to anti-CD47 antibody treatment

Abstract Anti-CD47 antibodies have been shown to inhibit the progression of several types of cancer by blocking the “don’t eat me” signals to macrophage through CD47/SIRPα interaction, causing phagocytosis of tumor cell. However, mechanistic details in the response of the cancer cells still remain to be explored. In this study, we investigated different cytokine levels in 4T1 mammary carcinoma induced mouse breast cancer model with or without anti-mouse CD47 monoclonal antibody treatment. The data showed that this cancer model presented significantly higher percentages of CD11b+, CD43+, CD80+, CD86+ and CD371+ cells after 1 week of 4T1 cells injection, CD11b+ cells percentage has been reached to 40% and 90% in spleen and bone marrow respectively at 2 weeks after 4T1 cells injection. After 4 doses of anti-mouse CD47 antibody treatment (i.p. injection per 2 days started from one week after 4T1 challenge), anti-CD47 antibody reduced significantly not only tumor size but also the levels of IL-1α in spleen (P=0.026) and of MCP-1/CCL2 in tumors (P=0.029). Interestingly, fresh isolated 4T1 induced breast cancer mouse spleen and bone marrow cells appeared 5%-10% CD11b+/Sca-1+ populations whereas in vitro culture of 4T1 cells had 5% of cells of Sca-1+/CD326+. When the freshly isolated 4T1 induced breast cancer mouse spleen and bone marrow cells were continuously cultured for 2–3 weeks, CD326+ cells became dominant and about 10% – 30% of population showed Sca-1+/CD11b+ positive. This study provided inside thoroughly investigated the response of cytokines and 4T1 cells induced mouse mammary carcinoma. Our data may further discover the mechanism for tumor growth and metastasis.