Figure 5.

Cytokine cascade in VL. There are two main patterns of cytokine activation, leading to the expression of Th-1 or Th-2 phenotype of T-cell polarization, respectively. While the Th1 response empowers the parasite clearance, the Th2 activation facilitates the parasite persistence in macrophages and dendritic cells. The innate immune response activation usually consists of the expression of both Th1 and Th2 cells, but an unbalanced response may lead to the development of VL even in immunocompetent hosts.