Low sPD-1 plasma levels were associated with brisk tumor-infiltrating lymphocytes (TILs), moderate levels with non-brisk TILs, and high levels with absent TILs in primary melanoma patients indicating engaged T cells may produce more mPD-1 but low soluble forms and peripheral tumor specific T cells may constitute the main source of elevated PD-1 levels (82). The gene discussed is HOXD13; the disease is neoplasm.