CD4 and tuberculosis: Moreover, TB vaccine candidates currently in clinical trials are not expected to induce CD8+ T cell immunity, both because these vaccines contain CD4 antigens, which are not immunodominant CD8 antigens (e.g., Ag85b) and they utilize delivery systems which are relatively inefficient in introducing antigen into the MHC Class I-restricted processing and presentation pathway (http://www.aeras.org/candidates/#candidates).