Test Details: Immunohistochemical testing is carried out on biopsy/resected tissue specimen. This testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody. CD8 is a transmembrane glycoprotein functioning as a co-receptor for the T-cell receptor, expressed in the suppressor/cytotoxic T-lymphocytes in addition to a subset of NK cells. CD8 is a marker of many types of T-/NK-cell lymphomas.