Immunohistochemical Detection of γ/δ T Lymphocytes in Formalin-fixed Paraffin-embedded Tissues

T lymphocytes can be distinguished based on the composition of the T-cell receptor (TCR) chain in alpha/beta T cells and gamma/delta T cells. Correspondingly, alpha/beta lymphomas can be distinguished from gamma/delta lymphomas. The latter are rare neoplasms, which are usually confined to particular organs and tissues and carry a dismal prognosis. Until recently, monoclonal antibody (mAb) clone g3.20 to the TCR gamma-chain was the reagent of choice for the immunohistochemical detection of gamma/delta T cells and lymphomas in standard formalin-fixed paraffin-embedded tissues. However, due to technical problems, mAb g3.20 became recently unavailable. Our attempts to identify another commercially available clone to the TCR gamma-chain were unsuccessful. However, we were able to identify a mAb (clone H-41, SC-100289; Santa Cruz, Dallas, TX) to the TCR delta-chain. H-41 works well in immunohistochemistry on paraffin-embedded tissue and comparison with previously stained cases, shows superior immunolabeling to mAb g3.20. H-41 to the TCR delta-chain appears to be a suitable reagent for the replacement of mAb g3.20.