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M López-Botet

Publications and source records attributed to M López-Botet.

82 records · Page 5Linked to original sources
PubMed1984

Interleukin 2 and interferon-gamma are not sufficient to induce natural killer-like activity in human T cell clones.

The role of interleukin 2 (IL 2) and interferon (IFN)-gamma in the maintenance of natural killer (NK)-like activity mediated by human cytolytic T cell clones was investigated. When cultured in standard supernatant (SN) obtained by phytohemagglutinin stimulation of human mononuclear cells (containing both IL2 and IFN activities), several mixed lymphocyte culture-derived clones displayed cytolytic activity directed against the K562 cell line; in addition, some of these clones also lysed specific target cells bearing the sensitizing alloantigens. When cultured in IL2-containing SN obtained from the Jurkat cell line, the NK-like activity was selectively abrogated within 4-5 days. However, by culturing cells again in standard SN the cytolytic activity was completely restored. The possibility that inhibitory molecules in Jurkat SN could be responsible for the loss of NK-like activity was ruled out by experiments showing that cytotoxicity could be induced by mixtures of Jurkat and standard SN. In addition, a source of affinity chromatography-purified IL2 also failed to maintain NK-like activity. Moreover, addition of recombinant IFN-gamma in combination with purified IL2 did not prevent the loss of NK-like activity. The present results indicate that neither IL2 nor IFN-gamma are sufficient to maintain NK-like activity and suggest that other molecule(s) are required.

Cells, Cultured↗
PubMed1983

Induction of natural killer-like cytotoxicity in cultured human thymocytes.

Supernatants containing interleukin 2 (IL 2) induce strong proliferation and expression of natural killer (NK)-like activity in human thymocytes. Different supernatants were compared for: (a) IL 2 activity, (b) thymocyte proliferation capacity and (c) induction of NK-like cytotoxicity. All these activities were present in a partially purified IL2 preparation obtained by gel filtration chromatography (Mr 15 000-20 000). However, in supernatants from different sources and in the 15 000-20 000-Mr semipurified fractions, we observed that the NK-like cytotoxicity inducer effect did not correlate with either the mitogenicity or the IL2 activity. The presence in the supernatants of interleukin 1 (IL 1), interferon (IFN) or phytohemagglutinin (PHA) does not seem to be a prerequisite for the induction of NK-like cytotoxicity, since this activity was (a) fully present in supernatants devoid of IL 1, IFN and PHA, (b) absent in preparations of IL 1 and (c) not augmented after supplementation of the supernatants with IFN-gamma. We also investigated the cellular characteristics of the precursor thymocytes responsive to IL 2 supernatants. Removal of the T3+ cells at the initiation of the culture abrogated the proliferative response and eliminated the generation of NK-like cytotoxicity. Under the same conditions, removal of the HTA1+ population increased the proliferation and did not affect the NK-like activity. Our results suggest that: (a) either IL 2 is not responsible for the induction of NK-like cytotoxicity or its action is modulated by other molecules, and (b) the precursor-responder population is preferentially included in the mature T3+ subset.

Cell Line↗
PubMed1983

Natural killer-like cytotoxicity of human T-cell clones against various target cells.

MLC-T cells from two different donors were cultured after limiting dilution (0.3 cells/well) in medium containing T-cell growth factor. Clones showing lytic activity against K-562 in a preliminary screening were expanded and tested against various NK-sensitive target-cell lines (Chang, T-24, Daudi, and Molt-4) and phytohaemagglutinin blasts derived from the stimulator cells. Ten growing clones maintained their activity against K-562 and were able to lyse the other cell lines. A significant heterogeneity was nevertheless noticed in the lytic efficiency of the different clones against the various target cells. Taken together, our data indicate that single clones are able to lyse different NK-sensitive targets.

Cell Line↗
PubMed1983

In vitro immune cell function in six cases of immunoproliferative small intestinal disease after long term remission.

We have studied several parameters of in vitro immune cell function in peripheral blood mononuclear cells from six patients with immunoproliferative small intestinal disease after long term remission. We have observed two groups of patients with different patterns of response. (a) After stimulation with pokeweed mitogen (PWM) and Staphylococcus aureus, three patients showed a significant reduction of the Ig synthesis (A, G and M) and the proliferative response. In two of them, we found increased spontaneous suppressor T cell activity. In the third case, the diminished response could not be attributed, according to our assays, either to suppressor T cells, lack of T helper activity (although the number of OKT4+ cells was diminished) or an intrinsic B cell defect. The three patients showed normal or augmented NK activity and an inversion of the OKT4+/OKT8+ ratio was detected in two of them. (b) The remaining three patients showed a normal Ig synthesis after stimulation with PWM and a slightly depressed IgM synthesis in response to S. aureus. They expressed a normal T helper cell function and did not show increased spontaneous suppressor T cell activity. They had low levels of natural killer cytotoxicity and the OKT4+/OKT8+ ratio was not significantly altered. Taken together, our data indicate that significant alterations of the in vitro immune response can be found in peripheral blood mononuclear cells of some immunoproliferative small intestinal disease patients after long term remission.

Adult↗
PubMed1981

Removal of PHA from supernatants containing T-cell growth factor.

Supernatants of human PBL cultures stimulated with PHA contain a lymphokine named T-cell growth factor (TCGF). To remove the contaminant PHA from these supernatants, we have designed a simple and effective method based on the binding properties of this lectin to chicken red blood cells. This procedure completely removes the functional activities of a PHA solution, both in lectin-induced cellular cytotoxicity against erythroid targets and in DNA synthesis of fresh PBL. The TCGF activity remaining in the supernatants after absorption with CRBC is dependent on the cellular concentration employed in the preparation of the supernatants. The absorption procedure does not remove significant TCGF activity in the supernatants prepared at high cellular concentrations (5 X 10(6) cells/ml), whereas in those prepared at low cellular concentrations (1 X 10(6) cells/ml) a partial loss of TCGF activity is detected.

Animals↗
PubMed1981

Human large granular lymphocytes: spontaneous and interferon-boosted NK activity against adherent and nonadherent tumor cell lines.

Human natural killer (NK) cells against K-562 tumor cells have been morphologically identified as large granular lymphocytes (LGL). We have investigated whether LGL are also responsible for NK activity against a variety of adherent and nonadherent tumor cell lines. LGL-enriched fractions, obtained by centrifugation of nonadherent mononuclear cells on discontinuous density gradients of Percoll, contained high levels of spontaneous and interferon- (IFN) boosted NK activity against each of the target cells tested. In contrast, the LGL-depleted functions, which contain most of the typical small lymphocytes, were devoid of NK activity and did not develop appreciable activity after treatment with IFN. The ability of the different fractions to exert NK activity correlated with their capacity to form conjugates with nonadherent tumor cells. Reconstitution of the different fractions with macrophages did not increase the NK activity of already cytotoxic fractions and did not induce appreciable activity in the LGL-depleted fractions. On the other hand, mixtures of highly cytotoxic and nonreactive cell fractions did not reveal the presence of suppressor cells for NK in the nonreactive fractions. Taken together, our data demonstrate that both spontaneous and IFN-boosted NK activity is confined to the LGL-enriched fractions and suggest that LGL are the main effector cells exerting NK cytotoxicity against a variety of adherent as well as nonadherent tumor cell lines.

Cell Adhesion↗
PubMedDate not supplied

[Production of tumor necrosis factor alpha and interleukin-6 by alveolar macrophages from patients with rheumatoid arthritis and interstitial pulmonary disease].

The aim of this study was to measure the production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) by alveolar macrophages in patients with rheumatoid arthritis and interstitial lung disease (ILD). Rheumatoid arthritis patients diagnosed by ACR criteria (n = 8) with associated ILD documented by pulmonary function tests and high resolution computerized tomography scanning, and 12 healthy volunteers (6 smokers and 6 nonsmokers). We determined the spontaneous and induced production of bacterial lipopolysaccharides (LSP), TNF-alpha and IL-6 by alveolar macrophages obtained by bronchoalveolar lavage. The macrophages were isolated by Ficoll-Hypaque gradient centrifugation and plastic adherence and cultured in serum-containing medium (low endotoxin) in the presence and absence of LPS (100 ng/ml). TNF-alpha and IL-6 levels contents were determined in supernatants by ELISA. In the patient group both spontaneous and induced production of TNF-alpha were significantly higher than in controls (p < 0.01). Macrophages stimulated with LPS in patients with rheumatoid arthritis and ILD also released greater amounts of IL-6 than did those of the healthy controls. IL-6 spontaneous and induced production was significantly lower in smokers than in nonsmokers. TNF-alpha and IL-6 production in patients with rheumatoid arthritis and ILD, studied in bronchoalveolar lavage specimens reveals that alveolar macrophages are hyperreactive in these patients, who are possibly sensitized as a consequence of the inflammatory lung process inherent to the disease. Further study is needed to define the pathogenic role of these mediators.

Aged↗