B cell depletion promotes melanoma tumor growth in a CD4+ T cell–dependent manner

B cells constitute ∼15% to 20% of tumor-infiltrating lymphocytes in melanoma. Their presence in the tumor microenvironment correlates with improved survival and enhanced response to immune checkpoint blockade therapy. Yet, the functional contribution of B cells to melanoma immunity remains unclear. In this study, we showed that both genetic and antibody-mediated B cell depletion significantly promoted melanoma progression in mice. Immune profiling revealed that, although B cell percentages were