Non-toxic concentrations of retinoic acid (RA) inhibited the spontaneous activity of human natural killer (NK) cells. RA also inhibited the activation of human NK cells by treatment with partially purified human leukocyte interferon (HulFN alpha) or with inducers of IFN alpha and IFN gamma. Full expression of the inhibitory action required prolonged exposure of human peripheral blood leukocytes to RA. Implications of these findings for the use of retinoids in the treatment of human malignancies are discussed.
We describe the production of marmoset lymphoblastoid cell interferon (IFN). Optimal yields of IFN were obtained when EBV-transformed lymphoblastoid cell lines (LCL) at a cell density of 1 X 10(6)/ml were incubated with 100 HAU Sendai virus/ml for 24 h. Sendai-virus-induced marmoset lymphoblastoid cell IFN was acid-stable and exerted antiviral activity on both homologous and heterologous human cells, thus allowing its classification as IFN alpha. Marmoset lymphoblastoid cell IFN did not inhibit the growth of herpesvirus-transformed marmoset T-or B-cell lines, but markedly enhanced marmoset NK-cell activity against human myeloid leukemia target cells. The use of lymphoblastoid cell IFN in marmosets in vivo may contribute to an understanding of the pathogenic role of IFN in herpesvirus-induced lymphoproliferative diseases.
Monoclonal antibodies with specificities for subsets of human leukocytes have been used for the characterization of interferon (IFN) gamma-producing cells. The production of IFN gamma was demonstrated to be a function of OKT3+T lymphocytes. The capacity to secrete IFN gamma was not restricted to the OKT4+ or the OKT8+T-cell subset. BA-1+B lymphocytes and Leu7+ natural killer cells did not contribute to the production of IFN gamma. Ia+, OKM1+ monocytes served an auxiliary function in the production of IFN gamma. The requirement for accessory monocytes, however, was not absolute, because monocyte-free preparations of long-term cultured IL2-dependent T lymphocytes retained the capacity to secrete IFN gamma.
Summary. Immune responses in vitro of some species of marmosets to herpesvirus-associated antigens expressed on virus-transformed lymphoblastoid cell lines (LCL) were studied by determining lymphocyte proliferation, interferon production, and the induction of cytotoxic effector cells in mixed lymphocyte-LCL cultures (MLLC). Autologous Epstein-Barr virus (EBV)-transformed B-cell lines induced neither lymphocyte proliferation nor interferon production in MLLC, while autologous Herpesvirus ateles (HVA)-transformed T-cell lines stimulated responder
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