SPECIFIC EPITOPE-INDUCED CONVERSION OF CD8+ MEMORY CELLS INTO EFFECTOR CYTOTOXIC LYMPHOCYTES-T INVITRO - PRESENTATION OF PEPTIDE ANTIGEN BY CD8+ T-CELLS

The requirements for the conversion of CD8+ memory T cells into effector class I major histocompatibility complex (MHC) K(d)-restricted cytotoxic T (T(c)) cells in vitro have been studied. Purified CD8+ splenocytes from influenza A/WSN-primed BALB/c (H-2d) Mice stimulated with a synthetic nucleoprotein peptide 147-158 R156- (NPP) alone generated T(c) cells specific for influenza virus-infected target cells. No additional requirements for accessory cells or their lymphokine products were necessary indicating that peptide antigen (Ag) in association with K(d) was presented on CD8+ T cells.The evidence for presentation of NPP by CD8+ T cells was supported by the use of CD8+ memory T cells from semiallogeneic bone marrow radiation chimeras of P1-->F1 type (H-2b-->[H-2d X H-2b]F1). Memory CD8+ splenocytes from A/WSN-immune chimeras did not develop into secondary effector T(c) cells as a result of a 4-day culture with NPP alone, however, were able to do so if NPP was presented by K(d)-bearing Ag-presenting cells. In addition, these results exclude the possibility of direct recognition of free NPP molecules by the specific T cell receptor of CD8 + memory Tcells. CD8+ memory splenocytes (H-2b) from chimeras were also able to develop into functionally active T(c) cells as a result of presentation of D(b)-restricted synthetic peptide (NP 366-374) with a sequence derived from influenza virus nucleoprotein with high affinity for D(b) MHC class I molecules. Blockade of endogenously produced interleukin 2 (IL-2) activity by anti-IL-2 or anti-IL-2 receptor monoclonal antibody in the culture of CD8+ memory Tcells during a 4-day NPP stimulation completely abolished T(c) cell generation, indicating that the utilization of this lymphokine is absolutely required for the secondary T(c) cell development. These findings demonstrate that CD8+ memory T cells per se are able to recognize the restimulating epitope as a result of its presentation by CD8+ T cells and develop into cytolytically active and highly specific T(c) cells with no requirements for other cellular helper components or their lymphokine products.