Characterization of human T suppressor‐inducer, ‐precursor and ‐effector lymphocytes in the antigen‐specific plaque‐forming cell response

Suppression of an antigen‐specific plaque‐forming cell response of human blood lymphocytes can be effected by Tμ⁺ cells that have been primed previously by antigen in vitro for 6 days. While lacking the capacity to suppress the plaque‐forming response directly, these primed Tμ⁺ suppressor‐inducer cells stimulate a subpopulation of unprimed Toy⁻ cells to differentiate to Tγ⁺ suppressor‐effector cells. The Tμ⁺, Tγ⁺ and Tμγ⁻ subsets have been shown to be heterogeneous populations of cells. Therefore, the functionally defined T suppressor‐inducer, ‐precursor and ‐effector cells were characterized by OKT monoclonal antibodies and by the capacity to form rosettes with autologous erythrocytes (ar⁺). Evidence will be presented that in vitro a T4⁺μ⁺ar⁻ cell induces a T8⁺μγ⁻ ar⁺ precursor cell to differentiate to a T8⁺γ⁺ar⁻ suppressor‐effector cell. A similar T suppressor‐effector cell can also be isolated directly from peripheral blood of normal donors.