Abs using the kappaII-A2 V gene segment predominate the @entity1 Ab repertoire to the @entity327 b (Hib) polysaccharide (PS). All A2 anti-Hib PS Abs sequenced to date possess a 10-amino acid L chain complementarity-determining region-3 (CDR-3) having an insertional @entity369 ( @entity534 ) at position 95a, the V-J junction. These findings suggest an essential requirement for this conserved @entity534 residue in determining Hib PS-binding affinity. We examined this requirement by performing chain recombination experiments in which a series of A2 L chains, differing at position 95a, were combined individually with an Fd region known to generate a Hib PS-combining site when paired with an A2- @entity534 (95a)-Jkappa1 V region. Hib PS binding of the recombinant Fabs was evaluated quantitatively using a radioantigen-binding assay. Fabs having A2 L chains with either @entity534 or @entity376 in position 95a in combination with Jkappa1 gave equivalent and strongest binding to Hib PS. Fabs having A2-Jkappa1 L chains with either @entity669 , @entity2228 , @entity493 , @entity368 , @entity563 , or @entity1889 in position 95a, or having an A2- @entity534 (95a)-Jkappa3 L chain, gave intermediate binding. Fabs having A2-Jkappa1 L chains with @entity2227 or @entity492 at 95a or with no junctional residue showed little or no Hib PS binding. These results demonstrate the importance of L chain junctional residue, as well as Jkappa usage and CDR-3 length, in determining Hib PS-binding affinity. Contrary to expectation, an @entity534 junctional residue is not essential for generating either high or intermediate affinity-binding sites.

Role of kappa II-A2 light chain CDR-3 junctional residues in human antibody binding to the XXXX type b polysaccharide.

@entity1 :: ('9606', 'Species') :: ['human'] @entity2227 :: ('CHEBI:29987', 'Chemical') :: ['glutamate'] @entity2228 :: ('CHEBI:57305', 'Chemical') :: ['glycine'] @entity368 :: ('CHEBI:25017', 'Chemical') :: ['leucine'] @entity327 :: ('727', 'Species') :: ['Haemophilus influenzae'] @entity534 :: ('CHEBI:16467', 'Chemical') :: ['Arg'] @entity376 :: ('CHEBI:25094', 'Chemical') :: ['lysine'] @entity492 :: ('CHEBI:29995', 'Chemical') :: ['aspartate'] @entity563 :: ('CHEBI:17822', 'Chemical') :: ['serine'] @entity1889 :: ('CHEBI:26986', 'Chemical') :: ['threonine'] @entity669 :: ('CHEBI:18186', 'Chemical') :: ['tyrosine'] @entity493 :: ('CHEBI:16449', 'Chemical') :: ['alanine'] @entity369 :: ('CHEBI:29016', 'Chemical') :: ['arginine']
@entity327 :: (727,Species) :: ['Haemophilus influenzae']
