Alterations of intralesional and lymph node gene expression and cellular composition induced by IL-12 administration during leishmaniasis

Changes in gene expression and cellular distribution in the lymph node and at the site of infection, the footpad, during Leishmania major infection an d/or IL-12 administration were evaluated. Otherwise susceptible BALB/c mice given IL-12 are able to resolve infection. Interestingly, iNOS was not ind uced in the lymph node by IL-12, yet, nitric oxide is critical in the contr ol of leishmaniasis. However we observed an increase in iNOS at the lesion site in response to IL-12. These results reflect the importance of examinin g the primary site of infection. We observed no changes in inflammation at the lesion site; however, IL-12 promoted art early inflammatory response in the lymph nodes. IL-12 administration differentially affected both the loc al and systemic immune response to invading leishmanial parasites. IL-12 in duced iNOS at the lesion site and an early granulomatous inflammation in th e lymph node; therefore, we hypothesize that these are key events responsib le for the resolution of disease in BALB/c mice treated with IL-12.