Regulation of hapten-specific T and B cell responses by suppressor cells.

We have described a model system of immunoregulation in which gene products associated with both the H-2 and Igh complexes guide a series of cellular interactions. The Igh restriction represents the requirement for T cell recognition of Igh-linked NPb-related idiotypic determinants. The data provide additional evidence that the T and B cell Igh products are distinct. Immunoglobulin products are involved in the selection of T cell receptors; Igh genes are not expressed in T suppressor cell. The H-2 restrictions generally involve the I-J subregion. These restrictions are imposed by the presentation of antigen or suppressor factor on a specialized population of I-J bearing, antigen-presenting cells, thereby functioning in a manner analogous to that proposed for the induction of helper T cells. The NP suppressor cell pathway consists of multiple cellular elements, including at least 3 distinct T cell populations and 2 or more distinct antigen-presenting populations. Generally, specific soluble suppressor factors produced by each Ts cell subset are involved in the cellular communication process. The terminal phases of the suppressor cell cascade involve an antigen dependent non-specific bystander mechanism. Tables IX and X summarize our present view of the NP suppressor cell cascade. It is still not possible to include all the other experimental models involving suppressor cell interactions into the above scheme. However, the disparities between the various systems have in some cases narrowed and in other instances suggested that multiple mechanisms of immune regulation may occur concurrently.