title: Production of alpha-lymphotoxin by human T-cell subsets.
abstract: Human T cells were isolated from peripheral blood lymphocytes (PBL) and sensitized to allogeneic PBL in a one-way mixed-lymphocyte culture. These sensitized T cells were fractionated on the basis of their possession of Fc receptors for IgG (TG+) or IgM (TM+), or the absence of both IgG and IgM receptors (TG-M-). When restimulated with alloantigen of the same derivation, TG+, TM+, and TG-M- cells yielded almost equal amounts of cytotoxin. Anti-alpha-lymphotoxin serum neutralized most of this cytotoxic activity indicating that alpha-lymphotoxin (alpha-LT) constituted most of this activity. Although TG-M- cells function as effectors in allogeneic cytotoxicity, TG+ cells lyse IgG-coated targets in an antibody-dependent cell-mediated cytotoxic (ADCC) reaction, which has been shown to be mediated in part by alpha-LT. Whether TM+ cells can be cytotoxic is not clear. In addition, freshly isolated human T-cell subsets were stimulated with phytohemagglutinin-P (PHA-P). After PHA stimulation, TG+, TM+, and TG-M- cells produced similar amounts of soluble cytotoxin, which was largely neutralized by anti-alpha-LT. The TG+ cells incorporated less thymidine than the TM+ or TG-M- cells. Likewise, OKT4+ and OKT8+ subsets, isolated with the aid of monoclonal OKT8 or OKT4 antibody and complement, yielded lymphotoxin after stimulation with PHA. It is shown that all T-cell subsets, as defined here, can produce lymphotoxin. Furthermore, depending on the assay system, cytotoxicity can be clearly demonstrated in all of these subsets, except in TM+ cells, where positive and negative results have been reported.
mesh_terms: D000911:Antibodies, Monoclonal; D000920:Antibody-Dependent Cell Cytotoxicity; D002469:Cell Separation; D004261:DNA Replication; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D007519:Isoantigens; D008213:Lymphocyte Activation; D008233:Lymphotoxin-alpha / Q000096:biosynthesis*; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007519:Isoantigens; D008233:Lymphotoxin-alpha