TCL1A-expressing B cells are critical for tertiary lymphoid structure formation and the prognosis of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a malignant tumor with a poor prognosis. Traditional treatments have limited effectiveness. Regulation of the immune response represents a promising new approach for OSCC treatment. B cells are among the most abundant immune cells in OSCC. However, the role of B cells in OSCC treatment has not been fully elucidated. Single-cell RNA sequencing analysis of 13 tissues and 8 adjacent normal tissues from OSCC patients was performed to explore differences in B-cell gene expression between OSCC tissues and normal tissues. We further investigated the relationship between differentially expressed genes and the immune response to OSCC. We utilized tissue microarray data for 146 OSCC clinical samples and RNA sequencing data of 359 OSCC samples from The Cancer Genome Atlas (TCGA) to investigate the role of T-cell leukemia 1 A (TCL1A) in OSCC prognosis. Multiplex immunohistochemistry (mIHC) was employed to investigate the spatial distribution of TCL1A in OSCC tissues. We then investigated the effect of TCL1A on B-cell proliferation and trogocytosis. Finally, lentiviral transduction was performed to induce TCL1A overexpression in B lymphoblastoid cell lines (BLCLs) to verify the function of TCL1A. Our findings revealed that TCL1A was predominantly expressed in B cells and was associated with a better prognosis in OSCC patients. Additionally, we found that TCL1A-expressing B cells are located at the periphery of lymphatic follicles and are associated with tertiary lymphoid structures (TLS) formation in OSCC. Mechanistically, upregulation of TCL1A promoted the trogocytosis of B cells on dendritic cells by mediating the upregulation of CR2, thereby improving antigen-presenting ability. Moreover, the upregulation of TCL1A expression promoted the proliferation of B cells. This study revealed the role of B-cell TCL1A expression in TLS formation and its effect on OSCC prognosis. These findings highlight TCL1A as a novel target for OSCC immunotherapy.