Isolation and expression of human cytokine synthesis inhibitory factor cDNA clones: homology to Epstein-Barr virus open reading frame BCRFI

We have demonstrated the existence of human cytokine synthesis inhibitory factor (CSIF) [interleukin 10 (IL-10)]. cDNA clones encoding human IL-10 (hIL-10) were isolated from a tetanus toxin-specific human T-cell clone. Like mouse IL-10, hIL-10 exhibits strong DNA and amino acid sequence homology to an open reading frame in the Epstein-Barr virus, BCRFI. hIL-10 and the BCRFI product inhibit cytokine synthesis by activated human peripheral blood mononuclear cells and by a mouse Th1 clone. Both hIL-10 and mouse IL-10 sustain the viability of a mouse mast cell line in culture, but BCRFI lacks comparable activity in this assay, suggesting that BCRFI may have conserved only a subset of hIL-10 activities.

Antigen specific and MHC nonrestricted cytotoxicity of T cell receptor alpha beta+ and gamma delta+ human T cell clones isolated in IL-4

IL-4 has been shown to act as a growth factor for human T cells. In addition, IL-4 can enhance CTL activity in MLC, but blocks IL-2 induced lymphokine activated killer cell activity in PBL. In our study, the cloning efficiencies, Ag-specific CTL activity and non-MHC-restricted cytotoxicity of CTL clones generated in IL-2 were compared to those generated in IL-4. In a first experiment, T cells were stimulated with the EBV-transformed B cell line JY and cloned 7 days later with feeder cells and either IL-2 or IL-4. In a second experiment, stimulation of the T cells was carried out in the presence of IL-2 plus anti-IL-4 antibodies or IL-4 plus anti-IL-2 antibodies in order to block the effects of IL-4 and IL-2, respectively, produced by the feeder cells. Although the cloning efficiencies in the second experiment were lower than those obtained in the first experiment, the cloning efficiencies obtained with IL-2 or IL-4 were similar in both experiments. The overall proportion of TCR alpha beta+ T cell clones cytotoxic for the stimulator cell JY established in IL-2 or IL-4 were comparable. A striking difference between the clones obtained in IL-2 or IL-4 was that a large proportion of the clones obtained in IL-4 expressed CD4 and CD8 simultaneously, whereas none of the clones isolated in IL-2 were double positive. Also gamma delta+ T cell clones could be established with IL-4 as a growth factor. TCR gamma delta+ T cell clones isolated in either IL-2 or IL-4 were CD4-CD8- or CD4-CD8+, but the proportion of CD4-CD8+ clones isolated in IL-4 was higher. Interestingly, one TCR gamma delta+ clone isolated in IL-2 was CD4+CD8-. Most of the TCR alpha beta+ and TCR gamma delta+ CTL-clones isolated in IL-2 lysed the NK cell sensitive target cell K562. In contrast, only a small proportion of the TCR alpha beta+ or TCR gamma delta+ CTL clones isolated in IL-4, lysed K562. One TCR gamma delta+ T cell clone (CD-124) isolated in IL-4 and subsequently incubated in IL-2 acquired lytic activity against K562.(ABSTRACT TRUNCATED AT 400 WORDS)

Antigen specific and MHC nonrestricted cytotoxicity of T cell receptor alpha beta+ and gamma delta+ human T cell clones isolated in IL-4

IL-4 has been shown to act as a growth factor for human T cells. In addition, IL-4 can enhance CTL activity in MLC, but blocks IL-2 induced lymphokine activated killer cell activity in PBL. In our study, the cloning efficiencies, Ag-specific CTL activity and non-MHC-restricted cytotoxicity of CTL clones generated in IL-2 were compared to those generated in IL-4. In a first experiment, T cells were stimulated with the EBV-transformed B cell line JY and cloned 7 days later with feeder cells and either IL-2 or IL-4. In a second experiment, stimulation of the T cells was carried out in the presence of IL-2 plus anti-IL-4 antibodies or IL-4 plus anti-IL-2 antibodies in order to block the effects of IL-4 and IL-2, respectively, produced by the feeder cells. Although the cloning efficiencies in the second experiment were lower than those obtained in the first experiment, the cloning efficiencies obtained with IL-2 or IL-4 were similar in both experiments. The overall proportion of TCR alpha beta+ T cell clones cytotoxic for the stimulator cell JY established in IL-2 or IL-4 were comparable. A striking difference between the clones obtained in IL-2 or IL-4 was that a large proportion of the clones obtained in IL-4 expressed CD4 and CD8 simultaneously, whereas none of the clones isolated in IL-2 were double positive. Also gamma delta+ T cell clones could be established with IL-4 as a growth factor. TCR gamma delta+ T cell clones isolated in either IL-2 or IL-4 were CD4-CD8- or CD4-CD8+, but the proportion of CD4-CD8+ clones isolated in IL-4 was higher. Interestingly, one TCR gamma delta+ clone isolated in IL-2 was CD4+CD8-. Most of the TCR alpha beta+ and TCR gamma delta+ CTL-clones isolated in IL-2 lysed the NK cell sensitive target cell K562. In contrast, only a small proportion of the TCR alpha beta+ or TCR gamma delta+ CTL clones isolated in IL-4, lysed K562. One TCR gamma delta+ T cell clone (CD-124) isolated in IL-4 and subsequently incubated in IL-2 acquired lytic activity against K562.(ABSTRACT TRUNCATED AT 400 WORDS)

Combined and sequential effects of human IL-3 and GM-CSF on the proliferation of CD34+ hematopoietic cells from cord blood

The proliferative effects of recombinant human interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) were investigated in semi-solid and liquid cultures of purified CD34+ hematopoietic cells obtained from umbilical cord blood. No important differences in overall cloning efficiencies in response to IL-3 or GM-CSF were observed in semi-solid medium in the presence of erythropoietin (Ep). However, GM-CSF was less effective for the development of erythroid bursts (BFU-E), and only IL-3 was observed to induce significant numbers of mixed-erythroid colonies (E-MIX). Both IL-3 and GM-CSF also induced proliferation of CD34+ in liquid cultures. Proliferative responses to IL-3 were found to be more rapid and stronger than to GM-CSF, although the number of initial responsive cells as judged by autoradiography were comparable. Enhanced proliferation of CD34+ cells both in semi-solid and liquid cultures was obtained in the presence of combinations of IL-3 and GM-CSF. The responses observed were less than additive, with the exception of the development of eosinophil colonies and clusters, where IL-3 and GM-CSF were found to act synergistically. In secondary cultures, proliferative responses to GM-CSF were strongly enhanced by preculture of CD34+ cells in IL-3 for four to 11 days, and to a lesser extent by preculture in GM-CSF. Finally, responses to IL-3 were not affected by preculture of CD34+ cells in the presence of GM-CSF. Our results indicate that there is a wide overlap of cells capable of proliferating either in response to IL-3 or to GM-CSF within the cord blood CD34+ compartment. However, differences in primary proliferation kinetics and increased responsiveness to GM-CSF following preculture suggest the importance of a sequential action of IL-3 and GM-CSF in the expansion of CD34+ cells.