The early IL-4 response to L. major is confined to CD4+ T cells expressing a Vβ4+Vα8+ T cell receptor that recognizes the Leishmania antigen LACK (Leishmania homolog of receptors for activated C kinase) (14, 77), in addition to mast cells and eosinophils at the site of infection and draining LN. This evidence concerns the gene IL4 and infection.