Background: The CD3 protein is a complex of five non-covalently linked peptide chains and is expressed on the surface of all T cells. CD3 is a specific T cell antibody. B cells, myeloid cells, macrophages and any other cells did not express CD3 except Purkinje cells in the cerebellum. The antibody recognizes both neoplastic and nonneoplastic T lymphocytes and NK cells. Some mycosis fungoides, pleomorphic lymphoma, and anaplastic large cell lymphoma can be negative for CD3. Nk-cell lymphoma can present as a cytoplasmic reaction.