Table 1

IC50 for inhibition of binding of copolymers to recombinant HLA-DR1 and -DR4 molecules by antigenic peptides

Biotinylated copolymer*HLA–DR1HLA–DR4
CII261–273HA306–318CII261–273HA306–318
YEAK40.03.540.010.5
YEK0.80.42.0≪0.1
YAK40.010.540.010.5
YEAND§ND23.0≪0.1
  • * Recombinant HLA-DR1 and -DR4 molecules were purified as described. 

  • YEAK with an average MW of 5,800; YAK, MW 20,000; EAK, MW 8,850; YEA, MW 7,600; and YEK, MW 11,050 (1.5 μM) were incubated with CII261–273 or HA306–318 peptides at a range of concentrations and with purified HLA-DR1 and -DR4 molecules at pH 5.0 followed by capture with class II-specific mAb and peptide detection with alkaline phosphatase-streptavidin. 

  • Data are presented as IC50 (μM, inhibitory concentration of CII or HA peptide giving 50% inhibition of the binding of biotinylated copolymers). These values were calculated based on the competitive binding assays (Fig. 1) (i.e. the higher the IC50 of the peptide, the more effective the copolymer in competing for binding of the peptide). 

  • § ND, not determined.