Cytotoxic activity of PBMCs from LTNP-100149, stimulated with peptide no. 42. (A) Chromium release assays were performed after incubating PBMCs with peptide no. 42 or peptide no. 64 plus IL-2 for 8 days, against autologous BCL targets labeled with 100 μCi (3.7 MBq) ⁵¹Cr and simultaneously pulsed with or without peptide no. 42 or no. 64. CD4⁺ and CD8⁺ cells were also purified after culture and assayed against appropriate target cells. Cultured cells were added to target cells at the indicated effector-to-target cell ratios. Results are representative of experiments on at least 2 visits. (B) Flow cytometry histograms, gated on TCRBV 17⁺ CD3⁺CD4⁺ lymphocytes, showing increased expression of granzyme B and perforin after incubation with peptide no. 42 plus IL-2 for 8 days.