B lymphocytes
B lymphocytes (B cells) are an important part of the human adaptive immune response and humoral immune response. Studies have found that B cells play an important role in anti-tumor immune response[84]. According to the analysis of the TCGA database, tumor infiltrating B cells (TIB) abundance is significantly higher in the NSCLC with EGFR mutation[85]. Studies have found that B cells usually existed in a tissue called tertiary lymphoid structure (TLS), and TLS was associated with a good prognosis[86]. The main function of B cells is humoral immune response, in lung tissue, B cells differentiate into plasma cells, which produce specific antibodies and recognize tumor associated antigens[86, 87]. In addition, activated TIB can activate tumor infiltrating T cells (TIT) through presenting tumor antigen to TIT and activating the anti-tumor effect of TIT[88]. However, regulatory B cell (Breg), a subtype of B cells, can inhibit immunity and promote tumor proliferation and metastasis[89]. It has been found that Breg can weaken the response of T cells and NK cells and facilitate the immune suppressive activity of regulatory T cells (Treg) by up-regulating immune regulatory ligands through secreting immunosuppressive factors such as IL-10, TGF-β[90]. Therefore, the relationship between B cells and EGFR-TKIs is complicated and needs further study.