The CD8 antibody reacts with the 32 kDa CD8 protein. CD8 stains cells with cytotoxic activity, including cortical thymocytes, cytotoxic/suppressor T-cells and a subset of natural killer cells. CD4 and CD8 positive and negative staining are indicative of T-cell neoplasms (1-2). CD4 and CD8 may also be used to differentiate between mycosis fungoides and cutaneous inflammatory processes (3-4). CD8 can be used in panels with CD4, CD56, TIA-1 to aid in identifying subsets of inflammatory skin diseases (5). Recently, CD8 has been used in panels with CD103, FOXP3, and PD-l for the identification of CD8+ tumor infiltrating lymphocytes and their potential value for immune therapy (6-8).