CD4 and melanoma: Other secretion systems of gram negative bacteria such as the type 5 secretion system (T5SS) or autotransporters have also been used to express TAA/TSA, as in the case of a Salmonella enterica that expresses murine melanoma antigens through the AIDA-I autotransporter; the nasal administration of this recombinant bacterium stimulated an antigen-specific response of CD4+ and CD8+ T lymphocytes, increased lymphocyte proliferation, and induced the production of Th1 cytokines, as well as a decrease in tumor growth and metastases development [135].