For instance, in studies of immunization of BALB/c mice with the recombinant A2 protein [16,34] or Leishmania ribosomal proteins [17] plus saponin, the animals were protected against infection, being this protection correlated with a decrease in parasite-specific IL-4 and IL-10 mediated response, as well as by low levels of parasite-specific IgG1 isotype antibodies. The gene discussed is IL4; the disease is infection.