T cell activation by Theileria annulata-infected macrophages correlates with cytokine production.
A major feature of the pathology induced by Theileria annulata is acute lymphocytic proliferation, and this study investigates the mechanisms underlying the intrinsic ability of T. annulata-infected monocytes to induce naive autologous T cells to proliferate. Different T. annulata-infected clones expressed different but constant levels of MHC class II, varying from < 1.0 x 10(5) to 1.5 x 10(6) molecules/cell, as measured by saturation binding. However, no correlation was found between the level of MHC class II expression and levels of induced T cell proliferation. Theileria annulata-infected cell lines and clones were assayed for cytokine mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR). The infected cells assayed produced mRNA specific for IL-1 alpha, IL-1 beta, IL-6, IL-10 and tumour necrosis factor-alpha (TNF-alpha), but not IL-2 or IL-4. One clone (clone G) did not produce mRNA for TNF-alpha. The degree of T cell proliferation induced by infected cells was directly correlated with the amount of mRNA produced for the T cell stimulatory cytokines IL-1 alpha and IL-6, as assessed by a semiquantitative technique. In contrast, cells infected with the related parasite T. parva produced mRNA for IL-1 alpha, IL-2, IL-4, IL-10 and interferon-gamma (IFN-gamma). Since T. parva-infected cells also induce naive autologous T cell proliferation, it seems likely that the production of IL-1 alpha by cells infected with either parasite is a major signal for the induction of non-specific T cell proliferation.
Division of Molecular Biology, Roslin Institute, Roslin, Scotland, UK.
D J
DJ
Brown
J D
JD
Campbell
G C
GC
Russell
J
J
Hopkins
E J
EJ
Glass
D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002460:Cell Line; D016207:Cytokines / Q000096:biosynthesis*; D015395:Histocompatibility Antigens Class I / Q000032:analysis; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D008213:Lymphocyte Activation; D008264:Macrophages / Q000469:parasitology / Q000502:physiology*; D008969:Molecular Sequence Data; D013601:T-Lymphocytes / Q000276:immunology*; D016796:Theileria annulata / Q000472:pathogenicity*
D016207:Cytokines; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II