DNA fragmentation as a characteristic of Lptn-mediated CD4⁺ T-cell death.

(A) DNA fragmentation was evaluated by enzymatic in situ labeling of DNA strand breaks (TUNEL assay), as described in “Materials and methods.” Briefly, CD4⁺ T cells were activated for 2 days with the indicated stimuli and subjected to labeling with FITC-dUTP and the TdT enzyme, followed by flow cytometric analysis. FACS profiles are representative of one out of 5 independent experiments. (B) Quantitative determination of TUNEL-based DNA fragmentation intensity performed as described in panel A. In the case of RANTES, 2 experiments were performed.