CD4-Specific Designed Ankyrin Repeat Proteins Are Novel Potent HIV Entry Inhibitors with Unique Characteristics
Figure 6
Effect of DARPin on T cell function and MHC class II interaction.
(A) The effect of the DARPin∶CD4 interaction was assessed in a binding assay based on rosette formation between CD4 and MHC class II expressing cells. Rosette formation was blocked by all tested CD4 specific DARPins (200 nM, shown are D25.2 and D55.2) or by the CD4-specific mAb Q4120 but not by the control DARPin E3_5. One out of two representative experiments is shown. (B) ELISpot assay to detect IFN-γ production by activated T cells showed no interference of DARPin 55.2 with CD4+ T cell activation. The response of two donors against CMV or streptokinase/streptodornase (SKSD) antigen was tested without DARPin (gray) and with nonspecific (blue) or CD4-specific DARPin (red) at 200 or 250 nM. One out of two independent experiments is depicted.