The CD8 (HIT8a) antibody recognizes a 68-kDa type-I transmembrane glycoprotein that consists of two disulfide-linked chains that form alpha homodimers or alpha/beta heterodimers. The most frequent CD8 antigen is CD8 alpha/beta heterodimer, which is e, Xenopus/Amphibian,pressed on 13-48 % peripheral blood suppressor/cytoto, Xenopus/Amphibian,ic T lymphocytes (Ts/Tc) and 70-80% thymocytes. In addition, a proportion of ??T cells and NK cells e, Xenopus/Amphibian,press CD8? homodimers. CD8(B) requires the presence of CD8a to be e, Xenopus/Amphibian,pressed on the cell surface. CD8 antigen is co-receptor for HLA class-I molecules.