SYNTHESIS OF TUMOR-NECROSIS-FACTOR-ALPHA AND INTERFERONS BY MONONUCLEAR-CELLS FROM THEILERIA-ANNULATA-INFECTED CATTLE

Bovine macrophage-derived tumour necrosis factor-alpha/cachectin (TNF- alpha was synthesized when peripheral blood mononuclear cells (PBMC) a nd purified adherent PBMC from naive and Theileria annulata-infected c attle were incubated in vitro with concanavalin A (Con-A) or bovine re combinant interferon gamma (Bo rIFN-gamma). TNF-alpha production was a lso induced when adherent PBMC were cultured with T. annulata macrosch izont-infected cells. In contrast, non-adherent PBMC from sublethally infected cattle produced interferon (IFN) when incubated with Hu rIL-2 , Con-A, phytohaemagglutinin (PHA) or T. annulata macroschizont-infect ed cells growing as cell lines in vitro. Whilst PBMC from lethally inf ected cattle spontaneously produced IFN-gamma during advanced stages o f infection, the sera of such animals contained type 1 IFN (alpha/beta ). IFN was also produced by T. annulata macroschizont-infected cell li nes maintained in vitro. This work suggests that cytokines serve as cr ucial links between proliferating Theileira-infected cells and the cha racteristic clinical symptoms of tropical theileriosis.