Role of the E^k Molecule in the Generation of Suppressor T Cells in Response to LDH_B

The role of the E^k (E_αE_β^k) molecule in the generation of suppressor T (T_s) cells specific for lactate dehydrogenase B (LDH_B) was studied using different approaches. First, lymph node cells from LDH_B‐primed B1O.A(2R) (A^kE^k) nonresponder mice were shown to suppress the LDH_B‐specific and A^k‐restricted proliferative response of T cells from the congenic responder strain B10.A(4R), which does not express E molecules (A^kE^o). Similarly, lymph node cells from primed CBA (A^kE^k) mice suppressed the anti‐LDH_B response of Lyt‐1⁺Lyt‐2^‐ T celfs (depleted of Lyt‐2‐bearing T_S cells) from the same mice. Second, in vitro priming of 2R (A^kE^k) T cells with LDH_B‐pulsed 4R (A^kE^o) antigen‐presenting cells (APC) generated T‐cell proliferation but not suppression. Third, nonresponder 2R mice were turned into responders by injecting them with LDH_B‐pulsed 4R APC or monoclonal Ia.m7 antibody that blocks the E^k molecule. The data demonstrate that expression of E^k molecules by the APC is necessary to generate LDH_B‐specific T_s cells, which in turn prevent the proliferation of Lyt‐l⁺Lyt‐2^‐ (probably helper) cells recognizing the same antigen in the context of the A^k molecule.