Characterization of the antigen-reactive T cell line mediating in vivo delayed type hypersensitivity established by antigen-induced interleukin 2.

The murine antigen-reactive T cell line has been established by antigen-induced interleukin 2 (IL-2) derived from immunized syngeneic mice. The surface markers of the cells showed Thy 1+, and Lyt 1+2-. The antigen-reactive cells require the presence of IL-2 for continuous proliferation. IL-2 from mouse, rat, or human sources all stimulate the T cell line growth. The T cell mitogen such as concanavalin A and antigen alone do not stimulate cell proliferation of the cells. The cells proliferate antigen-specifically in the presence of both IL-2 and antigen-presenting cells from histocompatible mice. Antigen-specific in vivo delayed type hypersensitivity response is inducible by injection of the T cells into naive syngeneic mice along with IL-2 and antigen. The reactivity of the T cell line found in vitro (proliferation) and in vivo (delayed type hypersensitivity) is highly antigen-specific, because the cells do not respond another antigen used for immunizing mice. The antigen-reactive T cell line produces neither IL-2 nor inhibiting factors such as neutralizing factors against preformed IL-2 activity and IL-2 production inhibiting factors, thus the cells are exclusive IL-2 acceptor. These results suggest that the interaction of antigen-induced IL-2 and IL-2 dependent antigen-reactive T cells may play a significant role in the induction/expression of in vivo delayed type hypersensitivity to specific antigen, because antigen-induced IL-2 is probably only a relevant IL-2 in the immunized mice.