Prostaglandin-E2 regulation of tumor necrosis factor receptor release in human monocytic THP-1 cells.

Recent in vitro studies indicate that tumor necrosis factor (TNF) production in human monocytic THP-1 cells is suppressed by action of arachidonic acid metabolite prostaglandin-E2 (PGE2). PGE2 stimulation of human monocytic cell line THP-1 demonstrates that PGE2 not only regulates TNF activity at production levels, but does so through the release of two soluble TNF receptors (BP-55, BP-75) as well. PGE2 can thus exert a regulatory effect on TNF biologic activity by interfering with its ability to reach cell membrane receptors.

Identification of the proteolytic enzyme which cleaves human p75 TNF receptor in vitro.

The extracellular domains of the human 55 and 75 kD TNF receptors (p55 and p75 TNF-R) are proteolytically cleaved to produce 30 and 40 kD soluble fragments, respectively. In this study, the enzymatic activity involved in the cleavage of human p75 TNF-R, named TNF-R releasing enzyme (TRRE), was identified in the culture supernatant of PMA-stimulated THP-1 cells using an activity assay system established by our group. When THP-1 cells were stimulated with PMA, TRRE was released rapidly into the supernatant, reaching maximal activity within 3 hours.

Host-tumor interaction in ovarian cancer. Spontaneous release of tumor necrosis factor and interleukin-1 inhibitors by purified cell populations from human ovarian carcinoma in vitro.

The biological activity of tumor necrosis factor (TNF alpha/beta) and interleukin-1 beta (IL-1 beta) can be blocked by soluble, naturally occurring molecules--TNF alpha/beta binding proteins (BP-55 and BP-75), derived from the extracellular portion of the 55- and 75-kDa TNF alpha/beta membrane receptors, and IL-1 receptor antagonist (IL-1ra), respectively. We examined the levels of these cytokines and their inhibitors in cell-free ascites of 18 patients with advanced ovarian carcinoma by ELISA. Levels of both TNF BP and IL-1ra dramatically exceeded those of TNF and IL-1; thus, it is unlikely that these cytokines are active in ascites from patients with this disease.

Mechanism of release of soluble forms of tumor necrosis factor/lymphotoxin receptors by phorbol myristate acetate-stimulated human THP-1 cells in vitro.

The mechanism involved in the release of the soluble forms of 55 and 75 kDa TNF and lymphotoxin (LT) membrane receptors was studied in a continuous human monocytic cell line, THP-1, in vitro. THP-1 cells were found to spontaneously release soluble forms of both 55 and 75 kDa TNF/LT receptors. Release was up-regulated by PMA, and optimal release was achieved at 10(-8) M PMA.

The role of lymphotoxin in the IL-2-driven differentiation of human lymphokine-activated T-killer (T-LAK) cells in vitro.

Brief stimulation of human peripheral blood mononuclear cells with PHA and subsequent coculture with IL-2 results by 5 days in cultures of human lymphokine-activated killer (T-LAK) cells. While IL-2 drives the proliferation of these cells in vitro, their maturation into functional effector cells capable of cytokine secretion and cell cytokines depends on the presence of other cytokines. The role of LT in the differentiation and proliferation of human T-LAK cells in vitro was investigated.

Release of soluble TNF/LT receptors from a human ovarian tumor cell line (PA-1) by stimulation with cytokines in vitro.

We have demonstrated the presence of the 55- and 75-kDa receptor for tumor necrosis factor (TNF) and lymphotoxin (LT) (TNF-R) in serum, and ascites from women with ovarian cancer. The present studies were initiated to begin to examine the possible cellular source of these receptors in women with ovarian cancer. Human ovarian tumor cells (PA-1) were cocultured for 24-48 hr with various levels of recombinant human cytokines (IL-1 beta, IL-4, IFN-gamma) and the supernatants were assayed by ELISA for the soluble forms of each receptor.

Measurement of the soluble membrane receptors for tumor necrosis factor and lymphotoxin in the sera of patients with gynecologic malignancy.

The shed portion of the 55 and 75 kDa membrane receptors for tumor necrosis factor (TNF) and lymphotoxin (LT) have been described in the serum of patients with cancer. This study was designed to determine whether serum levels of the 55 and 75 kDa soluble TNF/LT receptors (sTNFr) had clinical significance in patients with gynecologic malignancies. Serum samples from 79 patients with ovarian, endometrial, or cervical cancer were assayed for CA 125 levels by RIA and the 55 and 75 kDa sTNFr levels by ELISA.

Role of 55- and 75-kDa tumor necrosis factor membrane receptors in the regulation of intercellular adhesion molecules-1 expression by HL-60 human promyelocytic leukemia cells in vitro.

Most human cells express two TNF and lymphotoxin (LT) membrane receptors (TNF-R), of 55 and 75 kDa. The regulatory effect of these two receptors on intercellular adhesion molecules (ICAM-1) expression was examined in various human cell lines in vitro, including human lymphokine-activated killer T cells (T-LAK) cells and HL-60 cells. Rabbit antihuman TNF-R antisera specific for each receptor were employed as probes to selectively stimulate 55- and 75-kDa TNF/LT membrane receptor production.

Blocking factors (soluble membrane receptors) for tumor necrosis factor and lymphotoxin detected in ascites and released in short-term cultures obtained from ascites and solid tumors in women with gynecologic malignancy.

Studies were conducted to identify and establish the cell and tissue source of blocking factors (BF), materials that inhibit the bioactivity of human TNF and LT in vitro. Ascites and samples of solid tumors were collected from women with various gynecologic malignancies. Supernatants were collected from cultures of tumor and ascites cells after 24, 48, and 72 h.

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.

Trafficking of syngeneic murine lymphokine activated killer T cells following intraperitoneal administration in normal and tumor bearing mice.

Nongenetically restricted T cells may be important host effector cells in women with ovarian cancer receiving intraperitoneal (ip) IL-2 therapy. We developed an in vitro technique to produce murine lymphokine-activated killer T cells. Murine splenocytes were cultured in the presence of 1000 U/ml IL-2 for 10 to 15 days.

Growth of the endometrial adenocarcinoma cell line AN3 CA is modulated by tumor necrosis factor and its receptor is up-regulated by estrogen in vitro.

We demonstrate that tumor necrosis factor (TNF) has a biphasic effect on the growth of the human endometrial adenocarcinoma cell line AN3 CA in vitro. Low levels (0.2-5 pg/ml) of TNF were moderately growth stimulatory (up to 20% enhancement), while levels over 100 pg were growth inhibitory (up to 45% inhibition).

The regulation of TNF receptor mRNA synthesis, membrane expression, and release by PMA- and LPS-stimulated human monocytic THP-1 cells in vitro.

The regulation of the 55-kDa TNF receptor (TNF-R) mRNA synthesis, membrane expression, and TNF binding factor (BF) release was examined in resting and activated human monocytic THP-1 and human promyelocytic leukemia HL-60 cells in vitro. Cells were activated with phorbol myristate acetate (PMA) and bacterial lipopolysaccharide (LPS). TNF alpha cytolytic activity in the supernatant of THP-1 cells stimulated by PMA began to appear at 4 hr, reached a peak at 8 hr, and declined by 12 hr.

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.

Identification of tumor necrosis factor and lymphotoxin blocking factor(s) in the ascites of patients with advanced and recurrent ovarian cancer.

Ascites obtained from human ovarian cancer patients contains material(s) that inhibit the cytolytic activity of tumor necrosis factor (TNF) and lymphotoxin (LT) in vitro. These inhibitor(s) are found in ascites from ovarian cancer patients and are detected in very low amounts in the ascites from patients with nonmalignant hepatic disease. These ascites TNF/LT blocking factors are heat sensitive and heterogeneous with respect to molecular weight.

Enhancement of lymphokine-activated T killer cell tumor necrosis factor receptor mRNA transcription, tumor necrosis factor receptor membrane expression, and tumor necrosis factor/lymphotoxin release by IL-1 beta, IL-4, and IL-6 in vitro.

Co-culture with IL-2 can induce human T lymphocytes to proliferate and become nongenetically restricted, lymphokine-activated killer (LAK) cells in vitro. Our studies were conducted with long term cultured, human T-LAK cells from peripheral blood, which are 95 to 99% CD3+. We found that proliferating 7 to 10-day human T-LAK cells express TNFR, by using a 125I-TNF binding assay.