Interleukin-2 administered in vivo induces the growth and augments the function of cultured T cells in vivo.

The purpose of the studies being described was to determine if interleukin-2 (IL-2) administered in vivo can induce the growth and increase the number of antigen-activated T cells, and thereby augment specific T cell function in vivo. Initial experiments examined the in vivo growth of adoptively transferred T cells previously cultured long term with IL-2, since in vitro such long-term cultured T cells are exquisitely dependent on exogenous IL-2 for proliferation and survival. To identify and quantify donor T cells in vivo, experiments were performed with donor and host mice congenic for the T cell marker Thy 1. Host mice receiving congenic long-term cultured immune T cells were inoculated daily with purified IL-2 beginning on the day of cell transfer, and donor T cells within host ascites, spleen, and lymph nodes were enumerated at selected points in time. The experiments demonstrated that exogenous IL-2 induced in vivo growth of long-term cultured T cells proportional to the dose of IL-2 administered. Similar IL-2 regimens induced the in vivo growth and augmented the function of donor T cells that had been activated to express IL-2 receptors in vitro by 5-day culture with antigen but had not been cultured with exogenous IL-2. Thus, prior adaptation to growth with exogenous IL-2 in vitro is not necessary to render T cells responsive to IL-2 in vivo. In contrast to long-term cultured T cells in vivo (which died rapidly in vivo without exogenous IL-2), noncultured donor T cells proliferated in vivo in response to antigen.(ABSTRACT TRUNCATED AT 250 WORDS)