Given the observed increase of LAG-3 + B cells within the tumor microenvironment, along with their notable proliferation in the tumor-draining lymph nodes (tDLNs) of 4T1 and E0771 tumor-bearing mice, we proceeded to investigate the prevalence and potential functional roles of these cells in human breast cancer patients, as well as their broader implications for tumor biology and patient outcomes. Here, LAG3 is linked to breast carcinoma.