In vivo sensitization of T cells to hapten-conjugated syngeneic structures of major histocompatibility complex. I. Effect of in vitro culture upon generation of cytotoxic T lymphocytes.

Murine T cells were sensitized in vitro towards fluorescein isothiocyanate (FITC)-conjugated syngeneic spleen cells. The lytic activity of the effector cells generated was restricted to FITC-conjugated, H-2-compatible target cells. 2,4,6-Trinitrophenyl (TNP)-conjugated syngeneic targets were not lysed. A method is described for the in vivo sensitization of murine T cells towards TNP (or FITC)-conjugated syngeneic spleen cells. The procedure is based on the observation that a local graft of hapten-conjugated syngeneic spleen cells results in the development of sensitized prekiller T cells within the draining lymph node (LN). By mere in vitro incubation of such LN cells immunological specific anti-TNP (or anti-FITC)-reactive cytotoxic T lymphocytes (CTL) are generated. The in vitro differentiation of CTL requires 48-72 h; it is dependent on cell proliferation and is abolished by treatment of the LN cells with mitomycin C. Thus there is a separation between the sensitization of CTL precursors (which effectively takes place in vivo) and the phase of cell differentiation into CTL (which effectively takes place only in vitro). Similar to in vitro-sensitized CTL, the specificity of in vivo-sensitized CTL is dictated by the hapten used for the induction of the immune response and is restricted to hapten-conjugated syngeneic target cells.