title: Linker for activation of T cells (LAT), a novel immunohistochemical marker for T cells, NK cells, mast cells, and megakaryocytes: evaluation in normal and pathological conditions.
abstract: LAT (linker for activation of T cells) is an integral membrane protein of 36-38 kd that plays an important role in T cell activation. Using a rabbit polyclonal antibody generated against the cytosolic portion of LAT, we investigated the immunohistochemical expression of LAT in normal and pathological hematolymphoid tissues. LAT reacts with human T cells in paraffin sections, including decalcified bone marrow trephines. LAT appears early in T cells at the thymocyte stage and before TdT expression in embryos, and is expressed in peripheral lymphoid tissues, without restriction to any T cell subpopulations. In addition to T cells, natural killer (NK) cells (evaluated with flow cytometry), megakaryocytes and mast cells are also LAT-positive, whereas B cells and other myeloid and monocytic derived cells are negative. Tested on a total of 264 paraffin-embedded tissue biopsies, LAT reacted with the great majority (96.8%) of T/NK-cell neoplasms, covering the full range of T cell maturation. Although antibodies to both LAT and CD3 had a similarly high sensitivity in the staining of T/NK-cell lymphomas, when used in conjunction, they successfully identified a higher number of cases (98.4%). Atypical megakaryocytes from different hematological disorders, as well as mast cells in mastocytosis were also LAT-positive, but all neoplasms of B cell origin, Hodgkin's lymphomas, and several nonlymphoid malignancies were negative. These data indicate that the anti-LAT antibody may be of value to diagnostic histopathologists for the identification of T cell neoplasms.
authors.affiliation: Department of Pathology, University of Brescia, Brescia, Italy. facchetti@master.cci.unibs.it
authors.forename: F
authors.initials: F
authors.lastname: Facchetti
authors.forename: J K
authors.initials: JK
authors.lastname: Chan
authors.forename: W
authors.initials: W
authors.lastname: Zhang
authors.forename: A
authors.initials: A
authors.lastname: Tironi
authors.forename: M
authors.initials: M
authors.lastname: Chilosi
authors.forename: S
authors.initials: S
authors.lastname: Parolini
authors.forename: L D
authors.initials: LD
authors.lastname: Notarangelo
authors.forename: L E
authors.initials: LE
authors.lastname: Samelson
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000906:Antibodies / Q000378:metabolism; D015415:Biomarkers / Q000032:analysis; D001854:Bone Marrow Cells / Q000378:metabolism; D017252:CD3 Complex / Q000378:metabolism; D002352:Carrier Proteins / Q000276:immunology / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D005434:Flow Cytometry; D019337:Hematologic Neoplasms / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007694:Killer Cells, Natural / Q000378:metabolism*; D008223:Lymphoma / Q000378:metabolism; D008407:Mast Cells / Q000378:metabolism*; D008533:Megakaryocytes / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000276:immunology / Q000378:metabolism*; D013154:Spleen / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism*; D013950:Thymus Gland / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000906:Antibodies; D015415:Biomarkers; D017252:CD3 Complex; D002352:Carrier Proteins; C110810:LAT protein, human; D008565:Membrane Proteins; D010750:Phosphoproteins