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 .CD3 is a complex structure composed of five polypeptide chains (γ, δ, ε, ζ, and η) forming three dimers. CD3 builds a complex with the T-cell receptor on the membrane of T-lymphocytes responsible for the recognition of antigens leading to the activation of immune response. CD3 is the most commonly used pan-T-cell marker expressed in the vast majority of T-cell lymphomas.