Numerous experiments describe the upregulation of Ly49 receptors on CD8 T-cells as a result of stimulation with the cognate antigen (either during the infection or during the exposure to self-antigens) (10, 16, 17), cytokines (18, 19), or because of interactions with activated lymphocytes during the immune response (presumably, activated CD4 T-cells) (10–12). The gene discussed is CD8A; the disease is infection.