Cell‐Mediated Immunity to Bacterial Infection in the Mouse. Thymus‐Derived Cells as Effectors of Acquired Resistance to Listeria monocytogenes

Four lines of evidence indicated that thymus‐derived (T) cells play an essential role in the expression of cell‐mediated immunity (CMI) to Listeria . a) T cell depleted (ATx‐BM) CBA mice were unable to generate antibacterial immunity. b) Responsiveness was restored to ATx‐BM CBA mice by injection of CBA X C57BL F 1 thymocytes and essential CMI effector cells were derived from the F 1 thymocytes (identified by anti‐H‐2 sera). c) The activity of immune cells from intact CBA mice was abolished by anti‐theta treatment but d) enriched by treatment with anti‐B cell, anti‐macrophage serum. Evidence from adult thymectomized mice and that described in b) above, indicated that T cells which had left the thymus more than 6 weeks or less than 3 weeks prior to immunization could act as progenitors of effector T cells, and that no cooperaiion between these 2 cell classes was necessary for an optimal response.