Inhibitory effect of _GM/CCL18DC-primed T cells on proliferation of CD4⁺CD25⁻ effector cells. (A) T cells primed by _GMDCs, _GM/CCL18DCs, and _GM/IL-4DCs from nonallergic (NA) or allergic (A) donors were added at suppressor/responder ratios of 1:4, 1:2, and 1:1 to autologous CD4⁺CD25⁻ effector cells stimulated with soluble anti-CD3 and CD28 antibodies. CD4⁺CD25⁻ and CD4⁺CD25⁺ T cells were used as negative and positive controls, respectively. Irradiated autologous PBMCs were used as antigen-presenting cells. Proliferation was measured by incorporation of ³H-thymidine at 48 hours. Data are counts per minute ± SEM. *P < .05 (_GM/CCL18DCs vs _GMDCs). ∞P < .05 (_GM/CCL18DCs vs _GM/IL-4DCs). ^##P < .01 (_GM/CCL18DCs from A vs NA). (B) Control isotype, anti–IL-10, or anti–TGF-β1 neutralizing antibodies were added to the DC/T-cell coculture system. T cells primed by _GM/CCL18DCs or supernatants from DC/T-cell cocultures at different dilutions were added to effector cells as described as in Figure 5A. Data are counts per minute ± SEM. *P < .05 versus isotype-treated T cells primed by _GM/CCL18DCs. n = 3 experiments with triplicate wells for each condition.