The expression levels of
mRNA encoding a panel of 28 chicken
cytokines and
chemokines were quantified in intestinal lymphocytes following Eimeria acervulina and Eimeria tenella primary and
secondary infections. Compared with uninfected controls, transcripts of the pro-inflammatory
cytokines IFN-alpha, IL-1beta,
IL-6, and
IL-17 were increased up to 2020-fold following primary
infection. By contrast, following
secondary infection by either microorganism, pro-inflammatory mRNAs levels were relatively unchanged (< or = 20-fold). Transcripts encoding the Th1 and Th1 regulatory
cytokines IFN-gamma,
IL-2,
IL-10,
IL-12,
IL-15,
IL-16, and
IL-18 were uniformly increased 14-2471-fold after E. acervulina primary
infection, but either unchanged (IL-15, IL-16, IL-18), increased (IFN-gamma, IL-10, IL-12), or decreased (IL-2) following E. tenella primary
infection. Following
secondary infections, Th1
cytokine mRNA levels were relatively unchanged, with the exception of
IL-12 which was increased 1.5 x 10(5)-fold after E. acervulina and decreased 5.1 x 10(4)-fold after E. tenella
infection. Transcripts for the Th2 or Th2 regulatory
cytokines IL-3 and
GM-CSF were increased up to 327-fold following primary or
secondary infection with both parasites, while
IL-4 and
IL-13 mRNAs were decreased 25- to 2 x 10(5)-fold after primary or
secondary infection. The dynamics of chicken
chemokine expression revealed modest changes (<100-fold) following primary or
secondary infection except for
lymphotactin. When lymphocyte subpopulations were similarly analyzed, IFN-gamma,
IL-2,
IL-3,
IL-15, and MIF were most highly increased in TCR2(+) cells following E. acervulina
infection, while TCR1(+) cells only expressed high levels of
IL-16 following E. tenella
infection. In contrast, CD4(+) cells only expressed highest levels of
IL-10 after E. acervulina
infection, whereas these cells produced abundant transcripts for IFN-gamma,
IL-3,
IL-15, and MIF after E. tenella
infection. We conclude that
coccidiosis induces a diverse and robust primary
cytokine/
chemokine response, but a more subdued secondary response.