Purified anti-P antibodies from Pt 7 were preincubated with various inhibitory agents at concentrations between 100 and 0·05 µg/ml, then dispensed to (a) ribosomal MAP or (b) DNA coated plate in order to verify the residual binding activity. See Materials and methods for details. • Ribosomal MAP, □ MAP LKM, □ dsDNA, ▴ polydGdC, ○ ssDNA, ▵ polyApolyU.