Past literature has clearly highlighted that some antigens, such as the one of chickenpox, have the ability to generate, through various mechanisms (e.g., cross-reactivity, induction of autoantibodies, self-induced tissue lesions due to the activation of Interferon Gamma) a condition of autoimmunity, due to their ability to present the antigen and to overstimulate cells such as the host’s T CD4+ and/or CD8+ cells, putting the integrity of the immune system at risk. The gene discussed is CD8A; the disease is chickenpox.