Showing papers by "Dirk A. E. Dobbelaere published in 1990"
TL;DR: The Tac antigen component of the bovine interleukin-2 receptor was expressed as a Cro-beta-galactosidase fusion protein in Escherichia coli and used to raise antibodies in rabbits to investigate the expression of Tac antigen in a variety of Theileria parva-infected cell lines and also in three Theilaria annulata- infected cell lines.
Abstract: The Tac antigen component of the bovine interleukin-2 receptor was expressed as a Cro-beta-galactosidase fusion protein in Escherichia coli and used to raise antibodies in rabbits. These antibodies were used for flow cytofluorimetric analysis to investigate the expression of Tac antigen in a variety of Theileria parva-infected cell lines and also in three Theileria annulata-infected cell lines. Cells expressing Tac antigen on their surface were found in all T. parva-infected cell lines tested whether these were of T- or B-cell origin. T cells expressing Tac antigen could be CD4- CD8-, CD4+ CD8-, CD4- CD8+, or CD4+ CD8+. Tac antigen expression was observed both in cultures which had been maintained in the laboratory for several years and in transformed cell lines which had recently been established by infection of lymphocytes in vitro with T. parva. Northern (RNA) blot analysis demonstrated Tac antigen transcripts in RNA isolated from all T. parva-infected cell lines. Three T. annulata-infected cell lines which were not of T-cell origin were also tested. Two of them expressed Tac antigen on their surface. Abundant Tac antigen mRNA was detected in these T. annulata-infected cell lines, but only trace amounts were demonstrated in the third cell line, which contained very few Tac antigen-expressing cells. In all cell lines tested, whether cloned or uncloned, a proportion of the cells did not express detectable levels of Tac antigen on their surface. This was also the case for a number of other leukocyte surface markers. In addition, we showed that the interleukin-2 receptors were biologically functional, because addition of recombinant interleukin-2 to cultures stimulated cell proliferation. Recombinant interleukin-2 treatment also resulted in increased amounts of steady-state Tac antigen mRNA. The relevance of interleukin-2 receptor expression on Theileria-infected cells is discussed.
45 citations
Journal Article•
TL;DR: In this paper, the effect of cyclosporin A on the continuous proliferation of Theileria parva-infected T cells was tested and compared with its effect on the Con A-induced proliferation of bovine lymph node cells.
Abstract: The effect of cyclosporin A on the continuous proliferation of Theileria parva-infected T cells was tested and compared with its effect on the Con A-induced proliferation of bovine lymph node cells. The effect of rIL-2 on cyclosporin A-treated cells was also tested. Whereas the Con A-induced proliferation of bovine lymph node cells was completely inhibited by cyclosporin A, the continuous growth of T. parva-infected cells was only partly inhibited. In both cases the inhibition was accompanied by a reduction in the level of IL-2R/Tac mRNA and surface IL-2R expression. The cyclosporin A-mediated inhibition of Con-A stimulated lymphoblasts was, over a period of 5 days, largely abrogated by human rIL-2. In the short term, rIL-2 could also alleviate the growth inhibition of T. parva-infected cells caused by treatment with cyclosporin A. In the long term, however, rIL-2 enhanced the cyclosporin A-mediated inhibition of T. parva-infected cells, gradually leading to their complete growth arrest. This enhanced inhibition was accompanied by a further reduction in surface IL-2R expression, but not by a further decrease in the levels of steady state IL-2R/Tac mRNA. The fact that IL-2 can enhance the inhibition caused by cyclosporin A could be of relevance for the immunosuppressive activity of cyclosporin A.
12 citations
01 Jan 1990
TL;DR: Northern (RNA)blot analysis demonstrated Tacantigen transcripts inRNAisolated from all T.parva-infected cell lines, and it was shown that theinterleukin-2 receptors werebiologically functional, because addition ofrecombinant interleuk in-2 tocultures stimulated cell proliferation.
Abstract: cell lines. Cells expressing Tacantigen ontheir surface were found inallT.parva-infected cell lines tested whether these wereofT-orB-cell origin. Tcells expressing Tac antigen couldbeCD4-CD8-,CD4+CD8-,CD4-CD8+,orCD4+CD8+.Tacantigen expression was observed bothincultures whichhadbeenmaintained inthelaboratory forseveral years andintransformed cell lines whichhadrecently beenestablished byinfection oflymphocytes invitro withT.parva. Northern (RNA)blot analysis demonstrated Tacantigen transcripts inRNAisolated fromallT.parva-infected cell lines. ThreeT.annulata-infected cell lines which werenotofT-cell origin werealso tested. Twoofthemexpressed Tacantigen ontheir surface. Abundant Tacantigen mRNA wasdetected inthese T.annulata-infected cell lines, butonlytraceamountsweredemonstrated inthethird cell line, whichcontained veryfewTacantigenexpressing cells. Inallcell lines tested, whether cloned oruncloned, aproportion ofthecells didnotexpress detectable levels ofTacantigen ontheir surface. Thiswasalso thecaseforanumberofother leukocyte surface markers. Inaddition, weshowed that theinterleukin-2 receptors werebiologically functional, because addition ofrecombinant interleukin-2 tocultures stimulated cell proliferation. Recombinant interleukin-2 treatment also resulted inincreased amounts ofsteady-state Tacantigen mRNA.Therelevance ofinterleukin-2 receptor expression onTheileria-infected