Studies of membrane-associated and soluble (secreted) lymphotoxin in human lymphokine-activated T-killer cells in vitro.
The expression, release, and cytolytic activity of membrane-associated lymphotoxin was examined in cultures of phytohemagglutinin-P (PHA-P) and interleukin 2 (IL-2)-stimulated human T-lymphokine-activated killer (T-LAK) cells in vitro. Lymphotoxin (LT/TNF-beta) was identified on the membrane of T-LAK cells using flow cytometry. The membrane form of LT (mLT) is detected not only on T-LAK cells but also on LT-secreting human B-cell lymphoid cell lines, RPMI 1788 and Raji, but not on U937 or K562 cells. Maximum expression of mLT on T-LAK cells and the secretion of LT into the supernatant depended on the concentration of IL-2. Expression of mLT on T-LAK cells was reduced by stimulation with PHA-P; however, supernatant LT levels greatly increased. Both expression of mLT and release of soluble LT was reduced after incubation of T-LAK cells with actinomycin D (ActD) or cycloheximide (CHx). Paraformaldehyde-fixed T-LAK cells caused cytolysis of WEHI 164 cells in vitro, which was blocked by anti-LT but not anti-TNF antibody. These data support the concept that mLT may be an intermediate form to secreted LT, and that the mLT form is cytolytically active.
Abe
Y
Y
Department of Molecular Biology and Biochemistry, University of California-Irvine 92717.
Horiuchi
A
A
Osuka
Y
Y
Kimura
S
S
Granger
G A
GA
Gatanaga
T
T
D002460:Cell Line / Q000276:immunology; D002462:Cell Membrane / Q000276:immunology*; D003513:Cycloheximide; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology*; D015979:Killer Cells, Lymphokine-Activated / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology; D008233:Lymphotoxin-alpha / Q000276:immunology* / Q000302:isolation & purification; D010835:Phytohemagglutinins
D007376:Interleukin-2; D008233:Lymphotoxin-alpha; D010835:Phytohemagglutinins; D003609:Dactinomycin; D003513:Cycloheximide