In BALB/c mice, IL-4 production during the initial phase of infection with Leishmania major is necessary and sufficient to instruct Th2 cell development resulting in progressive disease - Himmelrich, H; Launois, P; Maillard, I; Biedermann, T; Tacchini-Cottier, F; Loksley, R M; Höcken, M; Louis, J A (J Immunol, 2000)