B lymphocytes in solid human malignancies

Abstract

Cancer remains one of the leading causes of death worldwide. Modern treatments such as immunotherapy and neoadjuvant chemotherapy exhibit promising results. However better understanding of the treatments may lead to optimizations and consequently better prognosis. In this thesis, we begin to categorize subpopulations of B cells in patients with malignancies. We demonstrate increased proportions of plasmablasts, switched memory and CD86+ B cells in tumor associated tissues. Noticeable skewing of Igλ/Igκ ratio of tumor infiltrating B lymphocytes (TIL-Bs) indicates tumor specific B cell expansion. Monoclonal expansion is confirmed by spectrartype analysis and sequencing the clonally expanded heavy chain, reveals somatic hypermutation. We conclude that B cells in cancer patients, display signs of CD4+ T cell dependent response against cancer. Furthermore, we investigate the effect of three conventional chemotherapeutic drugs on human B cells. We expose increased CD86 expression on B cells upon doxorubicin treatment which explains their escalated antigen presenting ability. In addition, doxorubicin results in decreased production of the cytokines, IL-10 and TNF-α. Investigation of B cells in urinary bladder cancer patients treated with neoadjuvant chemotherapy containing doxorubicin, reveals increased CD86 expression. Thus we argue, optimization of time and dose schedules may increase the potency of a chemotherapy and immunotherapy combination. TILs have increasingly been correlated with patient survival. TIL-Bs are reportedly a significant part of TILs. We illustrate that urinary bladder cancer patients, exhibit tumor associated follicular-like structures (FLSs) in the proximity of tumor where B cells and T cells interact. We demonstrate that FLSs and tumor-associated CD38+ plasma cells, in addition to IL-10 produced by non-B cells, may contribute to positive patient prognoses. On the contrary, IL-10 produced by tumor-associated Bregs, may affect the prognosis negatively. It is acknowledged that B cells undergo allelic exclusion. On the contrary to this understanding, we describe rare Igλ+ Igκ+ B cell populations in cancer patients which are increased in tumor associated tissues and present in activated B cell populations, as well as among switched memory B lymphocytes. Furthermore we demonstrate that they do not undergo somatic hypermutation and receptor editing. We conclude their emergence is due to the influence of tumor environment which is confirmed by Igλ+ Igκ+ B cell induction in culture with supernatant from a tumor cell line. Due to highly specific antigen receptors, B cells may be very effective antigen presenting cells (APCs). Further studies can reveal their role as APCs in cancer patients which may be exploited for CD4+ T cell adoptive immunotherapy.