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In situ expression of interleukin-10 and interleukin-12 in active human cutaneous leishmaniasis

Peter C. Melby, Fernando Andrade-Narvaez, Barbara J. Darnell, Guillermo Valencia-Pacheco
DOI: http://dx.doi.org/10.1111/j.1574-695X.1996.tb00059.x 101-107 First published online: 1 September 1996

Abstract

Th1-type cellular immune responses (interferon-γ) play a critical role in protection against Leishmania spp. infection, whereas Th2-type cytokines (interleukin (IL)-4, IL-10) have a counter-protective effect. IL-12, a potent inducer of Th1-type cellular immune responses, may play a pivotal role in the development of a protective response. We found that IL-10 and IL-12 mRNAs were expressed in most lesions of individuals with active cutaneous leishmaniasis. The quantity of IL-12 mRNA was highly variable but correlated strongly with the level of interferon-γ expression. IL-12 expression also paralleled the expression of IL-10, a potent in vitro suppressor of IL-12 and interferon-γ production. The more chronic, non-healing lesions generally had higher levels of IL-12 mRNA indicating that the expression of this cytokine alone was not sufficient to induce healing. Although the in situ production of IL-10 did not appear to block IL-12 expression, IL-10 may still promote disease by direct suppression of macrophage activation.

Keywords
  • Leishmania
  • Cytokine
  • Interleukin-10
  • Interleukin-12
  • Cellular immunity
  • Polymerase chain reaction