Níveis de citocinas em bovinos (Bos indicus) desafiados com o carrapato Boophilus microplus (Cannestrini, 1887)
Abstract
Boophilus microplus tick affects cattle productivity causing economic
losses in the order of billions of dollars annually. It is know that tick saliva exert
immunomodulatory effects, an evolutionary adaptation to the immune response
of the host that can counteract tick feeding. It has been suggested that the
outcome of many parasitic infections with regard to resistance or susceptibility
is determined by the pattern of response involving Th1 and Th2 cells, which
produce specific cytokines that may direct the immune response towards
different mechanisms. Limited information is available regarding to the host
response to B. microplus tick infestation. In an attempt to improve our
knowledge about cattle immune-response to ticks, this work determined the
expression levels of cytokines mRNAs in two groups of Nelore (Bos indicus)
calves: one control and other challenged by tick infestation. Our results
demonstrated a down-regulation of IL-2 (P < 0.03) mRNA levels in challenged
animals, while no effect of tick challenge was observed for IL-4, IL-8, IL-12p35,
TNF-α and MCP-1. The down regulation of an important Th1 cytokine suggests
a tendency towards a Th2 response pattern, which is in agreement with similar
studies conducted with other tick-host models.