CD4 and melanoma: Our previous study demonstrated that subcutaneous histotripsy ablation of melanoma tumors in murine hosts releases tumor antigens, with preserved immunogenicity, initiating both local (upregulation of intratumoral NK cells, dendritic cells, neutrophils, B cells, CD4+ T cells and CD8+ T cells), and systemic immune response, as evidenced by abscopal immune effects [20].