Enhancement of both arrest in cell growth and increase in cell death by Lptn.

(A) The kinetics of viable cell recovery, as measured by trypan blue exclusion, of purified CD4⁺ T cells activated for the indicated days with plate-bound CD3 mAb, in the presence or absence of either Lptn or RANTES. At day 0, 4 × 10⁶ cells/well were plated in each activation condition. Similar cell counts were obtained in the presence of RANTES, alone or in conjunction with its specific Ab, and are not shown. The figure represents the mean values ± SD (error bars) of 3 independent experiments. ▪, CD3; ♦, CD3 plus Lptn; ▴, CD3 plus Lptn plus anti-Lptn. (B) A typical flow cytometric profile of PI-stained CD4⁺ T cells. Cells were activated with CD3 mAb in the presence or absence of Lptn. At day 2 after activation, the different stages of cell cycle were analyzed for nuclei DNA content after PI uptake. The percentages of cells in the different stages (subdiploid [< 2n DNA], G₀/G₁ [2n DNA], and S+G₂+M [> 2n DNA]) are indicated. In parallel, CD4 staining ensured a 90% purity of the cultured cells (not shown). (C) Quantitative expression of the data shown in panel A. CD4⁺ T cells were activated for 2 days with the indicated stimuli. Each graph represents the mean values ± SD of 3 independent experiments.