CD 7

Becton Dickinson (Leu 9), Biodesign (WT1, WM31, 8H8.1), Biogenesis (WM31), Coulter (3A1), Cymbus Bioscience (WM31), Dako (DK24), GenTrak, Immunotech, Oncogene U3A1E), Sanbio (WT1), Seralab and Serotec (B-F12, B-5, HNE51).

Fresh frozen-tissue and fresh cytologic preparations.

CD 7 antigen is a cell surface glycoprotein of 40 kD expressed on the surface of immature and mature T-cells and natural killer cells. It is a member of the immunoglobulin gene superfamily and is the first T-cell lineage-associated antigen to appear in T-cell ontogeny, being expressed in prethymic T-cell precursors (preceding CD 2 expression) and in myeloid precursors in fetal liver and bone marrow and persisting in circulating T-cells. While its precise function is not known, there is a recent suggestion that the molecule functions as an Fc receptor for IgM (Lazarovits et al, 1994).

CD 7 is the most consistently expressed T-cell antigen in lymphoblastic lymphomas and leukemias and is specific for T-cell lineage and is therefore a useful marker in the identification of such neoplastic proliferations. In mature postthymic T-cell neoplasms, it is the most common pan-T antigen to be aberrantly absent and its absence in a T-cell population is a useful pointer to a neoplastic conversion.

Current antibodies are not immunoreactive in fixed tissues.

•Lazarovits AI, Osman N, Le Feuvre CE et al 1994. CD7 is associated with CD3 and CD 45 in human T cells. Journal of Immunology 153: 3956-3966.

Manual of diagnostic antibodies for immunohistology / Anthony S.-Y. Leong, Kumarasen Cooper, F. Joel W.-M. Leong.