Role of cytokines in the clinical manifestation of exophthalmia in newborn calves with tropical theileriosis.

The present study aimed to evaluate the pathology of the exophthalmia and the host-immune response in naturallyTheileria annulata-infected calves. The newborn calves detected positive for theileriosis were grouped into calves with theileriosis and absence of exophthalmia (n = 30), and calves with theileriosis and the presence of exophthalmia (n = 13). Sixteen healthy calves, free from any haemoprotozoal infection, were kept as healthy controls. A significantly (P <= .001) higher circulating levels of tumour necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) were estimated in diseased calves with and without exophthalmia as compared to healthy controls. Contrarily, significantly (P <= .01) lower interferon-gamma (IFN-gamma) level was estimated in diseased calves. The diseased calves with exophthalmia revealed significantly higher levels of TNF-alpha (P <= .001) and IL-10 (P <= .006) as compared to the diseased calves without exophthalmia. The diseased calves were not found to have an elevated intraocular pressure; rather they had significantly (P <= .001) lower intraocular pressure compared to the healthy controls. An elevated systemic TNF-alpha level might be attributed to the exophthalmia in calves with tropical theileriosis. The elevated circulatory IL-10 and reduced IFN-gamma levels could be one of the strategies ofTheileria annulatato escape the host immunity.