M. Rodriguez-sosa et al., Susceptibility to Leishmania mexicana infection is due to the inability toproduce IL-12 rather than lack of IL-12 responsiveness, IMM CELL B, 79(4), 2001, pp. 320-322
Almost all inbred mice are highly susceptible to parasites of the Leishmani
a mexicana complex that includes L. amazonensis and L. mexicana. Recent stu
dies have reported that T cells from L. amazonensis-infected mice fail to r
espond to IL-12 due to impaired IL-12R expression. Here, we demonstrate tha
t lymph node cells from L. mexicana-infected C57BL/6 and 129Sv/Ev mice resp
ond efficiently to exogenous IL-12 in vitro and produce IFN-gamma. Moreover
, we also show that deletion of signal transducer and activator of transcri
ption (STAT)4 gene in resistant STAT6(-/-) mice renders them susceptible to
L. mexicana. These findings indicate that an inability to produce IL-12 ra
ther than unresponsiveness to this cytokine is responsible for susceptibili
ty to L. mexicana. Moreover, the data also demonstrate that the STAT4-media
ted pathway is critical for the development of protective immunity against
cutaneous leishmaniasis, regardless of the species of Leishmania and/or gen
etic background of the mice.