ANTIGEN-SPECIFIC AND NONSPECIFIC MEDIATORS OF T-CELL-B-CELL COOPERATION .5. UNRESPONSIVENESS TO HGG INVITRO OF THESE 2 T-CELL SUBPOPULATIONS

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  • 1 January 1976
    • journal article
    • research article
    • Vol. 117  (5) , 1960-1965
Abstract
Two subpopulations of helper T [thymus-derived] cells (specific helper and nonspecific helper) were previously distinguished in the spleens of antigen-primed mice. These subpopulations can be differentiated by their modes of action and their activities and dose-response characteristics in mouse spleens primed with human .gamma.-globulin (HGG). In experiments to test whether the 2 subpopulations were derived from the same or different pool of precursors, mice were injected with limiting doses of a tolerogenic form of HGG. They were subsequently challenged with an immunogenic dose of HGG and their spleens assayed for specific helper and nonspecific helper activities in response to HGG in vitro. Over the dose range of tolerogenic HGG studied, both helper activities were equally tolerized. The question of the possible involvement of suppressor T cells in the maintenance of the state of unresponsiveness was also addressed quantitatively by the use of this model system. No active suppression was demonstrable in the maintenance of tolerance in either T cell subpopulation. Apparently the 2 types of helper T cells are derived from a common precursor pool or from different pools with identical susceptibilities to tolerogen. Suppressor cells do not appear to play a role in this form of tolerance.