Characterization of surface lymphotoxin forms. Use of specific monoclonal antibodies and soluble receptors.
Lymphotoxin (LT) is a cytokine related to TNF, found in human systems in both secreted and membrane bound forms. The well characterized secreted form is a trimer of a single protein, LT-alpha, whereas the surface form is composed of a complex between two related molecules, LT-alpha and LT-beta. Because there ... is a distinct receptor for the complex, the membrane form is believed to signal via events different from those elicited by TNF and secreted LT-alpha. By using a battery of anti-LT-alpha and LT-beta mAbs, it is clear that two LT surface forms exist on the surface of PMA-activated II-23 cells, a human T cell hybridoma. Assuming that these surface forms are trimers, a minor form appears early after induction having an apparent stoichiometry of LT-alpha 2/beta 1 and is recognized by one group of anti-LT-alpha mAbs and the p55-TNF receptor. The second and predominant form has an apparent LT-alpha 1/beta 2 composition and is recognized by a second group of pantrophic anti-LT-alpha mAbs and the LT-beta receptor. Neither of the heteromeric forms nor a putative LT-beta homotrimeric form were found to be secreted. The properties of surface LT on the II-23 cell system were similar to those of the surface LT forms on Chinese hamster ovary cells transfected with both LT-alpha and LT-beta genes and a number of lymphoid tumor lines. These experiments point toward the LT-alpha 1/beta 2 complex as the predominant membrane form of LT on the lymphocyte surface, and this complex is the primary ligand for the LT-beta receptor.
Mesh Terms:
Amino Acid Sequence, Animals, Antibodies, Monoclonal, Base Sequence, CHO Cells, Cercopithecus aethiops, Cricetinae, Fluorescent Antibody Technique, Glycosylation, Humans, Hybridomas, Kinetics, Lymphocyte Activation, Lymphotoxin beta Receptor, Lymphotoxin-alpha, Lymphotoxin-beta, Macromolecular Substances, Membrane Proteins, Molecular Sequence Data, Precipitin Tests, Protein Binding, Protein Conformation, Protein Processing, Post-Translational, Receptors, Tumor Necrosis Factor, Recombinant Fusion Proteins, Signal Transduction, Solubility, Tetradecanoylphorbol Acetate, Transfection, Tumor Cells, Cultured
Amino Acid Sequence, Animals, Antibodies, Monoclonal, Base Sequence, CHO Cells, Cercopithecus aethiops, Cricetinae, Fluorescent Antibody Technique, Glycosylation, Humans, Hybridomas, Kinetics, Lymphocyte Activation, Lymphotoxin beta Receptor, Lymphotoxin-alpha, Lymphotoxin-beta, Macromolecular Substances, Membrane Proteins, Molecular Sequence Data, Precipitin Tests, Protein Binding, Protein Conformation, Protein Processing, Post-Translational, Receptors, Tumor Necrosis Factor, Recombinant Fusion Proteins, Signal Transduction, Solubility, Tetradecanoylphorbol Acetate, Transfection, Tumor Cells, Cultured
J. Immunol.
Date: Jan. 01, 1995
PubMed ID: 7995952
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