Role of the HLA-G leader sequence peptide. OVAC 19 was incubated with different concentrations of Gsp as indicated in the figure. HLA-A2–binding HIV peptide (HIV-RT 476-484) was used as negative control at 100 μg/ml. HIV- and Gsp-pulsed OVAC 19 was then used as target in a 4-hour 51Cr-release assay. The HLA class I–restricted, tumor-specific CTL line RF1 was used as effector. Results from one of two experiments are shown.