Other possible target cells for IL-4 during VL may include dendritic cells (DC) (26, 27) and B cells (28) but more particularly CD4+ (26, 29) and/or CD8+ (30) T cells, whose active involvement has been shown not only to be essential to control primary infection and granuloma formation but also for successful SSG chemotherapy and therapeutic vaccination (15, 31, 32). This evidence concerns the gene CD4 and infection.