Role of the Ek molecule in the generation of suppressor T cells in response to LDHB.

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