The tissue division in memory subsets within the spleen and lung post‐primary PbA infection is consistent with the established model of CD8+ T‐cell memory whereby Tem cells persist for prolonged, but not indefinite lengths of time, within non‐lymphoid tissues, providing tissue immunosurveillance, and Tcm circulate between secondary lymphoid tissues, undergoing rapid proliferation upon re‐challenge (reviewed [43, 55]). The gene discussed is CD8A; the disease is infection.