Adherence of Candida albicans CBS 5982 to EAhy 926 cells (a–c) or human umbilical vein endothelial cells (d–f) in the presence of Ritonavir (RTV, left), Indinavir (IDV, centre) or Saquinavir (SQV, right). The bottom boxes show the results for the epithelial cell line HeLa S3, as previously published,16 for comparison (g–i). The HIV protease inhibitors were used at final concentrations of 500, 100, 20, 4 and 0.8 μmol l−1 (x-axis). The number of C. albicans colony-forming units (CFUs) was assessed under microscopic control. The CFUs derived from samples lacking HIV protease inhibitor were set to 100% (control). Specific adherence values (CFU) are shown as a percentage of the control (y-axis). Standard deviations varied between 1% and 14%. Significant (P < 0.05) results are indicated by black columns.