Effect of Pregnyl (lot 96H06 96D10) on the growth of AIDS-KS cells derived from a nodular KS lesion () and from a papular KS lesion (□) and on the growth of the immortalized KS Y-1 cell line (▪) (A). The cells were seeded at 3 × 10³ cells (1.5 × 10³ for KS Y-1 cells) per well in 96-well microplates and treated with increasing concentrations of Pregnyl. The cell counts were determined on day 7 with a Coulter Counter (Coulter, Hialeah, FL). Results are expressed as means (columns) ± SE (bars) of three independent experiments performed in duplicate. **P < .01, significant difference from control (ie, 10 ± 2 × 10³ cells per well for the KS-derived spindle cell cultures and 85 ± 15 × 10³ cells per well and for the immortalized KS Y-1 cell line). Experiments using other lots of Pregnyl (96H06 96D01 and 97C18 96K21) and experiments performed on spindle cells derived from sporadic and iatrogenic KS yielded similar results. Effect of Profasi (lot 96E10 95L08) on the growth of the same cell types in identical culture conditions (B). Similar results were also obtained when investigating [³H] thymidine incorporation instead of cell count (data not shown).