Positive selection of major histocompatibility complex-restricted suppressor T cells bearing the predominant idiotype in the immune response to lysozyme.

The lysozyme system provides an excellent model for studying the role of multiple major histocompatibility complex (MHC) genes in the induction and regulation of Ir-gene controlled immune responses. Immunization of H-2b mice leads to concomitant activation of helper and suppressor activities by different epitopes on hen egg-white lysozyme (HEL) and thus phenotype unresponsiveness to native HEL. HEL-specific suppressor T cells in C57BL/10 nonresponder mice show MHC restriction, because their enrichment on antigen-pulsed macrophage monolayers requires syngeneic macrophages as well as HEL. The expression of the selected suppressor function requires interaction between the restricted suppressor precursor cell and an HEL-triggered, suppressor-inducer T cell. The MHC-restricted suppressor precursors bear the predominant idiotype found on anti-HEL antibodies, whereas MHC-restricted helpers do not.