Protective Qa-1b-restricted CD8+ T cell responses have been described in several infection models, including Mycobacterium tuberculosis, Listeria monocytogenes, Salmonella typhimurium, and MCMV.36,39,48,71,72 While thus far these responses appeared to be directed against microbial peptides, we show here that a response to self-peptides can form a part of these protective responses. This evidence concerns the gene CD8A and infection.