Idiotypes of anti-phosphocholine antibodies: structural correlates

Phosphocholine-specific antibodies in mice are composed of three families of antibodies, the T15, the M603 and the M511, which are constructed by combinatorial association of a VH4 H chain and one of three different L chains, VK22, VK8 and VK24, respectively. Antiidiotypic antisera can be generated which (1) recognize all members of a family, i. e. anti-T15 IdX, anti-M603 IdX and anti-M511 IdX, (2) distinguish between members of a family, e. g. A/J anti-T15, or (3) recognize determinants on only a single anti-PC antibody. Consideration of protein sequences and L-chain polymorphisms and analysis of chain recombination experiments among Id-positive and -negative antibodies revealed that IdX are determined by the L chain. A similar approach demonstrated that the Id determinant defined by the A/J anti-T15 is dependent upon the L chain and the D region of the H chain.