Particularly haptens, which are not the primary target of antibodies in nature since they need to be coupled to larger proteins to serve as immunogen, are deeply intercalatedin the dimer interface.
Dimer interface: ca 1600 Å2
Haptens 410 Å2 +/- 150 (67% buried)
Peptides 670 Å2
Proteins 830 Å2