Abstract 5019: Characterization of sentinel node-derived antibodies from breast cancer patients

Abstract

Abstract Lymph nodes are one of the important sites in the body where immune responses to antigens are initiated. The tumor-draining lymph node or sentinel node is the first site where cancer cells and cancer-related antigens are most likely to spread. In response to antigen exposure and immune activation, the lymph node B cells undergo clonal expansion and somatic hypermutation, leading to the affinity-matured populations of effector B cells secreting antibodies that bind to the tumor. The cancer-draining node is therefore an ideal source of B cells that produce anticancer antibodies. In the present investigation, we have characterized the antibodies derived from immortalization of sentinel node B cells from 29 breast cancer patients. The antibodies were screened for their isotypes and for binding to breast cancers classified as luminal A, luminal B, HER2, and basal/normal subtypes, based on the expressions of estrogen, progesterone and HER2 receptors. The isotype analysis showed a higher percentages of antibodies belong to IgG (48%) and IgM (34%) isotypes along with a smaller share of IgA (18%). The cell-binding studies were conducted using ELISA, immunofluorescence microscopy, and flow cytometry techniques. Of the studied antibodies, about 28% showed binding to the tumor cells. The comparative studies of antibody-binding to breast tumor cells and non-cancer breast cells identified several antibodies showing differential binding profile. The binding analyses also demonstrated that all of the tumor-binding antibodies belonged to IgM isotype. It is evident from the results that the tumor-reactive antibodies are generated in the sentinel nodes of breast cancer patients; however, the absence of class-switched anti-tumor antibodies in the repertoire raises a possibility of tumor-induced node suppression leading to an inefficient humoral immune response towards tumor antigens. The results are important in assessing the tumor immune response/lymph node suppression, and the possible role of the autoantibodies in diagnosis and therapy of breast cancer. Citation Format: Girja S. Shukla, Stephanie C. Pero, Yu-Jing Sun, Chelsea L. Carman, David N. Krag. Characterization of sentinel node-derived antibodies from breast cancer patients. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5019. doi:10.1158/1538-7445.AM2015-5019