The autocrine role of tumor necrosis factor in the proliferation and functional differentiation of human lymphokine-activated T killer cells (T-LAK) in vitro.

The autocrine role of tumor necrosis factor alpha (TNF) in the proliferation and functional differentiation of human lymphokine-activated T-killer cells (T-LAK) in vitro was investigated. Human peripheral blood lymphocytes initially stimulated with IL-2 and phytohemagglutinin-P (PHA) for 48 h will proliferate for long periods in vitro in the presence of IL-2. These T-LAK cells have been shown to be 95% CD3 positive.

A 20 amino acid synthetic peptide of a region from the 55 kDa human TNF receptor inhibits cytolytic and binding activities of recombinant human tumour necrosis factor in vitro.

Tumour Necrosis Factor (TNF) and Lymphotoxin (LT) can exert a wide range of effects on cells and tissues and they are important effector molecules in cell mediated immunity. All these effects are induced subsequent to the binding of these cytokines to specific membrane receptors. Recently, two of these membrane receptors of 55 and 75 kDa, have been identified which share some amino acid (AA) homology in their N-terminal extracellular domains but differ in their intracellular domains.

Inhibition of human NK-induced cell lysis and soluble cell-lytic molecules with anti-human LT antisera and various saccharides.

The present study examines and compares the cytolysis of K-562 and MOLT-4 cells mediated by human natural killer (NK) cells from fresh peripheral blood and lymphotoxins (LT) derived from human lymphoid cell populations after lectin stimulation in vitro. Lymphotoxins were obtained from 5-hr concanavalin A (Con A)-restimulated human peripheral blood lymphocytes (PBL) which were precultured for 5 days in medium and fetal calf serum or with allogeneic human B-lymphoid cell lines. Two classes of probes were employed in both direct (cell) and indirect (supernatant) induced target-cell lysis: (a) various saccharides and (b) antibodies reactive with human LT forms.