Maintenance of growth transformation with Epstein-Barr virus is mediated by secretion of autocrine growth factors in two serum-free B-cell lines

Evaluation of various serum and animal protein free media for the production of a veterinary rabies vaccine in BHK-21 cells

We have carried out the adaptation of BHK-21 cells to two serum free (Ex Cell 520 and HyQ PF CHO) and three animal protein free media: Ex Cell 302, HyQ PF CHO MPS and Rencyte BHK. After a direct switch or a gradual adaptation, we have achieved BHK-21 cells growth in the following media: HyQ PF CHO, HyQ PF CHO MPS, Rencyte BHK and Ex Cell 302. The most suitable media for BHK-21 cells growth, with respect to cell density and specific growth rate, were HyQ PF CHO and HyQ PF CHO MPS. Hence we have selected these media to study cell growth and the production of rabies virus. Kinetic studies of cell growth in spinner flasks using the selected media have shown that a maximal cell density of 2x10(6) cells x ml(-1) was reached in both media. For rabies virus production, the viral titer obtained was 1.7x10(6) FFU x ml(-1) in HyQ PF CHO as well as in HyQ PF CHO MPS medium. The optimization of rabies virus production by BHK-21 cells grown in a 2 l bioreactor using the selected media, pointed to the following parameters: culture mode, perfusion rate and multiplicity of infection (MOI), as being the critical factors for achieving a good virus yield. When tested in mice, the activity of the experimental vaccines prepared on HyQ PF CHO MPS medium has shown a protective activity that meets WHO requirements.

Marek's disease virus-transformed chicken T-cell lines respond to lymphokines

Current assays for chicken interleukin-2 (IL-2) utilize mitogen-activated lymphocytes. However, very high inter-assay variability and sporadic high background proliferation limit their usefulness. In view of the above, several Marek's disease virus (MDV)-transformed T-cell lines (which grow well in a serum-supplemented medium) were tested for a response to chicken IL-2 when grown in serum-free media. Five of six lines examined showed a dose-dependent proliferative response to chicken T-cell conditioned media. One line, MDCC-CU14, was chosen for further studies. In addition to the tumor cells' dose-dependent responses to semi-purified chicken IL-2, they expressed T-cell activation antigens on the cell surface. Furthermore, the level of surface expression was enhanced on cells provided IL-2. Co-incubation of the tumor cells with monoclonal antibody INN-CH-16 (specific for an antigen on the surface of activated T-cells) and IL-2 resulted in a modulation of lymphokine-induced proliferation. Together, these data suggest that signalling mechanisms in MDV T-cell tumors are intact and that these lines can be used as an assay for chicken T-cell lymphokines. Furthermore, they provide an interesting model for the study of avian and mammalian T-cell transformation. Implications for the study of Marek's disease are also discussed.

Activity of soluble factors produced by Epstein-Barr virus-transformed human B lymphocytes on different cell lines

Self-stimulatory growth factors, produced by a human Epstein-Barr virus (EBV)-positive lymphoblastoid B cell line, named BA-D10-4, have been tested for the capacity to induce DNA synthesis in various human and animal cell lines, including lymphoid, either EBV-positive or EBV-negative, and non-lymphoid cell lines. It has been found that BA-D10-4 cells produce growth factors which seem to be essential for their sustained proliferation in vitro, and which increase DNA synthesis in different primate lymphoid cells, independently of the presence of the EBV genome and of the lymphocyte lineage.

Marked cell-type-specific differences in glycosylation of human interleukin-6

Human interleukin-6 (IL-6) secreted by cytokine- or endotoxin-induced fibroblasts, monocytes, keratinocytes, endometrial stromal cells, and endothelial cells, when analyzed under denaturing and reducing conditions, consists of a set of differentially modified phosphoglycoproteins of molecular mass in the range from 23 to 30 kD (a set of at least three O-glycosylated 23- to 25-kD species and a set of at least three N- and O-glycosylated 28- to 30-kD species). The 23- to 25-kD and 28- to 30-kD fibroblast-derived IL-6 species have been separately purified to homogeneity with the use of a combination of lectin and immunoaffinity chromatography. Glycosidase digestion experiments on such purified preparations confirmed that almost all human fibroblast-derived IL-6 species were O-glycosylated; additionally, the 28- to 30-kD species were N-glycosylated. Amino acid sequencing revealed that the major amino terminus in the fibroblast-derived 23- to 25-kD O-glycosylated IL-6 was at Ala28 whereas the major amino terminus in the 28- to 30-kD N- and O-glycosylated IL-6 was at Val30, suggesting that targeting of newly synthesized IL-6 polypeptides into the two different processing pathways in fibroblasts may be keyed to differences in the signal peptide cleavage site. Unexpectedly, IL-6 "constitutively" secreted by the Epstein-Barr virus (EBV)-infected human and primate (tamarin) B-cell lines designated sfBJAB and sfBT, respectively, consisted of a major apparently unglycosylated 21-kD species and a minor 25-kD N-glycosylated species.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for platelet-activating factor receptors in several B lymphoblastoid cell lines

Previous studies have shown that Raji, an Epstein-Barr virus (EBV)-immortalized Burkitt lymphoma B cell line, contains functional platelet-activating factor (PAF) receptors. Twelve other lymphoid cell lines, including Burkitt and non-Burkitt B cell lines, T cell lines, and a non B, non T cell line were tested for the presence of PAF receptors. Radioligand binding studies conducted at 4 degrees C revealed that six lymphoid cell lines of B cell origin (Raji, P3HR-1, BJAB, BJA/HR-1, Dakiki and PB-1) could specifically bind [3H]PAF. Treatment of four (Raji, P3HR-1, Dakiki and PB-1) of the above lymphoid cell lines with PAF resulted in an increase in free intracellular calcium, indicating that these specific PAF binding sites were functional PAF receptors. Other B cell lines (Daudi, B95-8, sfBT, CB-1), T cell lines (MOLT-4, CCRF-CEM) and a non B, non T cell line (NALM-6) had no PAF binding sites and showed no PAF-induced increase in intracellular calcium levels. These studies demonstrate evidence for the presence of PAF receptors on several B lymphocyte cell lines.