Identify the presence of IL-10 and IFN-y in leukocytes during theileria parva infection in cattle

Abstract

The gene expression of two immunoregulatory cytokines, IL-10 and IFN-y, during infection of bovine leukocytes with T. parva was investigated at the single cell level. Initial results obtained from in vitro studies with infected cells using RT-PCR showed that both Il.TO and IFN-y messages were present. The ability of Theileria-infected cells to produce Ils-l Otranscripts was a consistent feature. However, their ability to exhibit IFN-y messages was less consistent. On application of in situ hybridisation technique using bovine Il.s lO and IFN-y-specific riboprobes, it was demonstrated that most infected lymphocytes produced ll.,-l 0 and that few of these cells displayed expression of IFN~y transcripts. Thus, judging from the relative abundance of Il.>I0 and lack of IFN-y mRNA, the expression of Ilv lO, a cytokine known to inhibit IFN-y production and functions, was shown to be upregulated in leukocytes responding to T. parva infection in cattle. These experiments did not demonstrate the production of biologically active Il.s IO during the infection. However, the accompanying relative absence of IFN-y mRNA in situ may suggests that biologically active Il--I 0 was produced and blocked the production of IFN-y, an important effector TH I cytokine. The apparent upregulated expression of Ilv lOduring infection with T. parva is indicative of a regulatory role for this cytokine in the mediation of susceptibi"lity to acute disease. This parasite-instigated induction and upregulation of ll.,-I 0 expression may represent an important strategy by which intracellular T. parva eludes IFN-y-dependent cell-mediated immune destruction. Through its induction of tissue-damaging metalloproteinase, Il.s lOpresence also offers a biochemical explanation ·to - the possible mechanism of propagating the lymphoproliferative, immunopathologic and tissue destructive phenomena observed in ECF.