concanavalin-a and Malignant-Catarrh

The causal agent of sheep-associated malignant catarrhal fever (MCF), Ovine Herpesvirus-2 (OHV-2), can be propagated in IL-2-dependent lymphoblastoid cell lines derived from diseased cattle and deer providing a useful model for the investigation of the pathogenesis of MCF. In this study, five interleukin-2 (IL-2)-dependent cell lines were established from affected cattle to examine their growth regulation and cytokine transcription. All cell lines expressed CD2, CD5 and CD25. Three of the cell lines were CD4+ and one CD8+, whereas one cell was of mixed CD4 and CD8 phenotye. The growth of these cell lines was reduced when cultured with antibody against CD25, the IL-2 receptor alpha subunit. All cell lines showed a lack of response to Con A and their cell growth was inhibited by Cyclosporin A which is known to inhibit cytokine promoters. It was decided therefore, to examine the cell lines for the presence of mRNA of different cytokines. The results showed that the cell lines transcribed message for IFNgamma, TNFalpha, IL-4 and IL-10 whereas no mRNA for IL-2 or IL-1beta was detected. In conclusion, the OHV-2-immortalised cell lines resemble anergic T-cells which may be activated giving rise to the characteristic lesions of MCF.

Topics: Animals; Antigens, CD; Cattle; Cell Line; Concanavalin A; Cyclosporine; Cytokines; Flow Cytometry; Fluorescent Antibody Technique, Indirect; Gammaherpesvirinae; Immunosuppressive Agents; Malignant Catarrh; Phenotype; T-Lymphocytes; Transcription, Genetic

Lymphokine-supplemented long-term cultured bovine lymph node lymphocytes were characterized functionally and phenotypically. Lymphocytes from a normal and a malignant catarrhal fever (MCF) virus-infected animal were maintained without the addition of antigen or feeder cells. Lymphocyte cell lines obtained from both animals: (i) killed allogeneic fibroblasts and allogeneic and xenogeneic cultured tumor cell lines as measured in a 4-h 51Cr release assay, (ii) expressed the same T cell subset marker based on flow cytometry using monoclonal antibodies, and (iii) produced a lytic factor upon stimulation. In contrast, only cells from the MCF virus-infected animal could be maintained for more than 5 months supplemented with 2% Con A-generated lymphokine-containing supernatant. These results suggest that herpesvirus infection enhanced the proliferative capabilities of the cultured lymphocytes from the infected animal. Considering the proliferative and cytotoxic activity together with the T cell phenotype, these data indicated that effector cells are lymphokine-activated killer cells.

Topics: Animals; Cattle; Cell Line; Concanavalin A; Cytotoxicity, Immunologic; Female; Fibroblasts; Interleukin-2; Killer Cells, Natural; Lymph Nodes; Lymphocyte Activation; Lymphocytes; Malignant Catarrh; Microscopy, Electron; Phenotype; T-Lymphocytes