Functional T-cell analysis. (A) STAT-5 phosphorylation after IL-2 stimulation in CD3⁺ T cells from a healthy donor (right panel) and P2 (left panel). The light lines represent isotype controls. (B) Proliferation of CD4⁺ (left panel) and CD8⁺ (right panel) T cells as determined by CFSE dilution after incubation of a 1:1 mixture of sorted CD3⁺ T cells and CD3-depleted PBMCs with medium (top panels), PHA (middle panels), or anti-CD3/anti-CD28 beads (bottom panels) for 5 days. The graphs show overlay histograms of the data obtained from the patient (bold line) and a healthy donor (light line). (C) Degranulation of activated T cells. Surface expression of the lysosomal marker protein CD107 (indicating T-cell degranulation) and intracellular expression of IFN-γ were determined on PHA blasts that were placed either in medium (left panels) or in medium containing anti-CD3/anti-CD28 beads for 5 hours. The dot plots are gated on CD3⁺ CD8⁺ T cells.