In the Lewis lung carcinoma model, vaccination efficiently increases the CD3+CD4+ and CD3+CD8+ T cell populations in the spleens and CD3+CD8+, CD3−CD8+, and CD11b+CD80+ cell populations in the tumors, suggesting the alteration of tumor microenvironments from cold to hot tumors. This evidence concerns the gene CD8A and Carcinoma, Lewis Lung.