CD30 is a transmembrane cytokine receptor belonging to the tumor necrosis factor (TNF) receptor superfamily. Mature CD30 has a molecular mass of 120 kDa. The intracellular part of CD30 possesses kinase activity, indicating a role in differentation and/or proliferation. CD30 expression is found on Hodgkin's and Reed-Sternberg cells, and on activated B and T lymphocytes. CD30 is also expressed by embryonal carcinoma cells. This antibody is a useful aid for the classification of anaplastic large cell lymphoma.