Figure 6

Plasticity of CD4⁺ T-cell subsets. The plasticity of CD4⁺ T-cell subsets is demonstrated in the murine model of leishmaniosis. In many chronic infectious diseases it is now recognized that sterilizing immunity is prevented by the action of T cells with regulatory function. Although regulatory T cells prevent complete elimination of the infection, they are crucial in inhibiting the development of secondary immunopathology. A balance is therefore achieved between infection-limiting Th1 immunity and immunopathology-limiting regulation. The regulatory activity might come from classical induced or natural Treg, but equally some Leishmania-specific Th1 cells may be re-programmed to become IL-10 producing regulatory cells.