Human T cell hybridomas secreting immune interferon

Examination of the inhibitory effects of interferon-gamma on interleukin-4-induced stimulation of resting B cells from NZB/NZW F1 mice

Percoll fractionation of NZB/NZW F1 mouse B cells revealed an increased ratio of low-density fraction ('activated' B cell fraction) and a decreased ratio of high-density fraction ('resting' B cell fraction), in comparison to normal mouse B cells. Resting B cells of B/W F1 mice were hyperresponsive to interleukin-4 (IL-4), with increased proliferation and IgG anti-DNA antibody production, in comparison to normal mice. The hyper-responses of resting B cells from NZB/NZW F1 mice to IL-4 were affected with dose dependency by interferon-gamma (INF-gamma); specifically, cell proliferation and anti-nuclear antibody production were suppressed in the presence of IFN-gamma. This suppressor action of IFN-gamma was most noticeable when it was added to the culture system simultaneously with IL-4. These findings suggested that the abnormally activated state of NZB/NZW F1 mice B cells can be attenuated by the action of IFN-gamma on resting B cells.

Inositol phospholipid turnover and protein kinase C translocation are stimulated by poly(I).poly(C) in human amnion cells (UAC)

Polyinosinic-polycytidylic acid, a potent inducer of inducer of interferon (IFN) production and activator of some IFN-induced enzymes, inhibits [3H]uridine incorporation into the RNA of vesicular stomatitis virus even in the absence of IFN synthesis, transiently triggers the breakdown of inositol phospholipids and activates the translocation of protein kinase C. Since IFNs also have similar activities these results suggest that IFN induction and IFN function are realised through common biochemical pathways.

Efforts to produce human cytotoxic T-cell hybridomas by electrofusion and PEG fusion

Cytotoxic human T cells from different sources were fused with different types of human T-lymphoma cells and mouse B-myeloma cells using variations of the polyethylene glycol (PEG) method and electrofusion. Both techniques yielded proliferating hybridomas. The frequency of wells with proliferating hybridomas depended on the tumor fusion partner used; the best results were obtained with HSB-1, whereas fusions with JURKAT-1 and HPB-1 did not yield any hybridomas. For one tumor cell line (HSB-1), considerably more hybridomas were obtained with electrofusion than with the PEG fusion (with or without heat shock). There was no consistent relationship between the presence or absence of cytotoxic activity of the T lymphocytes against the tumor fusion partner and the yield of hybridomas. In human-human as well as in human-mouse hybridomas most of the lymphocyte derived chromosomes were lost. Four of the more than 600 hybridomas tested showed transient cytotoxic activity, but in none of them this function could be immortalized. Two of the hybridomas obtained with CEM-1 as tumor fusion partner expressed low levels of lymphocyte-derived CD3 antigens. Two hybridomas obtained with HSB-1 were highly invasive in vitro in rat hepatocyte cultures, whereas HSB-1 tumor cells were not.

Inverse relationship between constitutive gamma interferon production and human T-cell lymphoma/leukemia virus expression in cultured T lymphocytes

Particular interest in human T lymphocyte lymphoma/leukemia virus (HTLV) derives from the close association of HTLV with several types of human mature T lymphocyte malignancies and the strong possibility that HTLV is the causative agent of this group of leukemias and lymphomas. This is the first report to show that HTLV expression in T lymphocytes cultured in vitro is inversely proportional to constitutive gamma interferon production. Of 16 fresh T lymphocyte cultures established from patients with mature T lymphocyte neoplasias, 3 were grown continuously for over 3 years and 13 were grown for 2 to 8 months in culture. Of the 16 cultures, 9 were HTLVp19 positive and interferon negative, whereas the remaining 7 were HTLVp19 negative or weakly positive and also interferon positive (12 to 105 U/ml). The prototype HTLV-positive T-cell line (HUT102) was examined over a long-term culture and after selective cell cloning for high virus yield. Results indicate that early-passage, low-HTLV-producing HUT102 cells constitutively produced significant levels of gamma-immune interferon. In late-passage and cloned HUT102 cells, an increase in HTLV production was concordant with a decrease in constitutive interferon production and the loss of mature T lymphocyte antigens. Transformation of human umbilical cord blood lymphocytes by HTLV was possible only after cocultivation with the non-interferon, high virus-producing, cloned HUT102 T lymphocytes. The inverse relationship between interferon and HTLV production was also observed when normal human umbilical cord blood and adult T lymphocytes were transformed by HTLV and maintained in culture.

The generation of stable human T-cell hybridomas which constitutively produce interleukin-2 and chemotactic factor

We report the successful generation of human T-cell hybridomas that constitutively secrete lymphokines. An acute lymphoblastic leukemia T-cell line, CCRF-H-SB2, free of reverse transcriptase and mycoplasma, was sensitized to hypoxanthine, aminopterin, and thymidine (HAT) by selecting out a mutant deficient in hypoxanthine guanine phosphoribosyl transferase (HGPRT) in 8-azaguanine. Peripheral blood T lymphocytes from normal donors were incubated in vitro with 10 micrograms/ml of concanavalin A for 48 h and subsequently fused with the CCRF-H-SB2 HAT-sensitive cell line. Following 5 weeks in culture, 38 of 440 wells (8.6%) demonstrated hybridoma growth. Supernatants of these cultures were screened for interleukin-2 (IL-2), chemotactic factor, interferon, migration inhibition factor, and macrophage-activating factor activities. Twelve (of 38) hybrids exhibited IL-2 activity, and eight of these were successfully cloned. The highest secreting clone was demonstrated to have mRNA to IL-2 while the parent CCRF-H-SB2 had no detectable mRNA to IL-2. Three hybrid cultures produced chemotactic factor; one was successfully cloned and grown in serum-free medium, where it continued to constitutively produce chemotactic factor as well as IL-2 activity. The chemotactic factor was determined to have the same molecular weight (12,500 daltons) as leukocyte-derived chemotactic factor. Constitutive IL-2 production remained stable for over 12 months. None of the hybridomas tested produced detectable levels of gamma interferon, migration inhibition factor, or macrophage activation factor. Because these T-cell hybridomas produce lymphokines constitutively and this phenotype is stable, they can be an important source of highly purified human lymphokines for clinical and laboratory investigations.

The preparation of interferon gamma-producing T-cell hybridomas from jacalin-stimulated T lymphocytes and the SH9 T-cell line

Jacalin, a lectin(s) extracted from the seeds of Artocarpus integrifolia (Jackfruit), was shown to induce the production of gamma interferon (IFN gamma) in human peripheral blood mononuclear cells (PBMC) and human T-lymphocyte cultures. The amount of IFN gamma produced was enhanced in the presence of mezerein, a phorbol ester derivative. Fusion of jacalin stimulated T lymphocytes with the SH9 T-cell line resulted in the formation of T-cell hybridomas which spontaneously secreted IFN gamma. The spontaneous production of IFN gamma by T-cell hybridomas was not influenced by the presence of jacalin, although significant enhancement of production was observed when the cells were cultured in the presence of mezerein.

Constitutive production and characterization of interferon-gamma in a human T-lymphoblastoid cell line transformed by a human retrovirus

A human T-lymphoblastoid cell line, TCL-Fuj, constitutively produced a large amount of human gamma interferon (IFN) in culture fluids and has sustained stable IFN production for more than two years. When cells were incubated in RPMI-1640 medium with 10% fetal calf serum for three days, IFN activity was detectable at a cell density of 6 X 10(4) cells/ml, whereas 2,000-16,000 units of IFN per ml were produced at 5-10 X 10(5) cells/ml. IFN production was also detected even in serumfree medium and as early as 2 hr after cultivation in fresh medium. IFN was inhibited by treatment of cells with either actinomycin D or cycloheximide, indicating the requirement of IFN-mRNA and protein for de novo synthesis. The molecular weight of the IFN was 45,000-60,000 as determined by Sephacryl S200 gel filtration. Two activity peaks corresponding to molecular weights of 22,000 and 39,000 were obtained by SDS-polyacrylamide gel electrophoresis. Analysis by isoelectric focusing revealed charge heterogeneity with four species at pIs of 6.0, 7.1, 8.6, and 9.3. Conventional IFN-gamma inducers, concanavalin A and 12-O-tetradecanoyl-phorbol-13-acetate, further enhanced the production of IFN in this cell line.

Induction of gamma-interferon activity by elevated temperatures in human B-lymphoblastoid cell lines

When the human B-lymphoblastoid cell lines GM3299 and GM4408 were heat shocked, elevated levels of antiviral activity were detected. This antiviral activity has been characterized as the result of de novo synthesis of interferon (IFN) gamma. Levels of antiviral activity as high as 20,000 units/ml per 10(6) cells were found after heat treatment. By using anti-IFN-alpha and anti-IFN-gamma sera, it was shown that the high antiviral activity in GM3299 after heat shock is due to a synergistic effect of constitutively produced IFN-alpha and induced IFN-gamma.

Effect of IFN-gamma on the immune response in vivo and on gene expression in vitro

T lymphocytes produce a variety of immunoregulatory molecules including gamma interferon (IFN-gamma) and antigen-specific suppressor and enhancer factors. During our studies of active substances obtained from cloned T-cell lines, we observed that certain fractions administered to mice resulted in enhancement of immune responses. Preliminary characterization of the substance suggested that it could be IFN-gamma and we therefore undertook a study of the action of IFN-gamma produced by recombinant DNA methodology on immune responses. We found that for several antigens, administration of IFN-gamma to mice leads to two- to five-fold enhancement of antibody formation provided that the IFN-gamma and antigen are administered together. The effect was dose dependent, giving a maximal response at 500-600 anti-viral units per mouse. Preliminary studies suggest that the macrophage may be the target of IFN-gamma action. Addition of IFN-gamma to cultures of a macrophage cell line leads to a greater than 10-fold increase in the level of RNA coding for I-region-encoded cell surface molecules.