Fig. (4) The pre-activation of T lymphocytes and DC via TLRs down-regulates the proliferative ability in a two-MLR system.Panel A. Pre-treatment of DC and T cells with agents acting via TLRs is able to significatively inhibit a two-way MLR. A positive control was the measure of thymidine incorporation of cells not treated (DC + T cells). The data represent the mean of quadruplicate samples. The averages ± standard deviations (error bars) of three different experiments are shown. Similar results were obtained in three separate experiments from a variety of donor/recipient combinations. *, Samples that are significantly different (p < 0.05) from the control culture (DC + T cells).Panel B. A cocktail of mAb specific for the B7/CD28-family members added to the assay is able to revert the capability of T lymphocytes to proliferate. In addition, the presence of a cocktail of irrelevant isotype-matched mAb does not perturbate the inhibitory effect observed. The averages ± standard deviations (error bars) of three different experiments are shown. Similar results were obtained in three separate experiments from a variety of donor/recipient combinations.*Samples that are significantly different (p < 0.05) from the control culture (DC + T cells).**Samples that are significantly different (p < 0.05) from the control culture (DC + T cells + TLR activation).