The generally accepted "Gershonian" view of immunoregulation attributes T cell-mediated regulation of immune responses to the activities of discrete T cell subsets with specialized functions such as help, suppression, and contrasuppression. Several observations made in our laboratory are not compatible with this paradigm. For instance, careful quantitations of carrier-specific T cell help to hapten-specific B cells in an adoptive transfer system yielded complex dose-response curves that could not be explained on the basis of interactions between discrete subsets of helper and suppressor cells. Rather, the results were most easily interpreted according to a model based on the following assumptions: (1) Regulation of helper T cell activity is a dose-dependent, dynamic property of T cell populations that exhibit a high degree of connectivity (self-recognition) and (2) helper T cells have the ability to perform different functions, depending on the current activity of other interacting lymphocytes. A good example of cloned T cells capable of performing multiple immunoregulatory functions was provided by the IEk-specific self-reactive Lbd line which provided help, suppression, and contrasuppression to T cell dependent PFC responses (see Quintáns et al., 1986). Since these effects were strictly dependent on the levels of antigen-specific T cell help, we hypothesized that Lbd cells interacted with other T cells to modulate their function. In this paper, we directly test the hypothesis that activated T cells can interact directly with resting T cells and describe the proliferative component of a syngeneic T cell anti-T cell response induced by antigen and self-reactive helper and cytotoxic T cells. In a follow-up report, we will describe the effector component of the T anti-T cell response.(ABSTRACT TRUNCATED AT 400 WORDS)