Galactan-binding antibodies. Diversity and structure of idiotypes.

Abstract

A group of eight IgM hybridoma proteins induced with beta(1,6)-D-galactan-containing antigens has been characterized in terms of primary amino acid sequence and idiotype expression. The H chain amino acid sequences reveal very strong homology in the VH segment although several substitutions are seen that suggest the occurrence of somatic mutation in these IgM molecules. Significant sequence variation was observed in CDR-3, the region generated by the D segment, and the two recombination events, VH-D and D-JH. The number of amino acids in this region contributed by the D segment was found to vary from two to six, yet the overall length of CDR-3 was precisely maintained by the addition of amino acids on either side of D during the recombination processes. These additional amino acids are suggested to result from nucleotide addition by repair enzymes. Idiotypic analysis of these proteins, in conjunction with an assessment of the H chain sequences, has permitted an identification of the molecular basis of both cross-reacting and unique idiotypic determinants expressed by these molecules.

Molecular characteristics of anti-polysaccharide antibodies

“…From such animals, hybridomas producing anti-galactan antibodies were also obtained. Anti-galactan myeloma proteins express both IdX and IdI [41]. Figure 5 shows the kinetics of anti-galactan PFC in BALB/c mice of various ages immunized with arabinogalactan.…”

Affinity Repertoire of Monoclonal Antibodies Obtained by Primary or SecondaryIn VitroImmunization

“…Screening of antibody secretion was performed against DNP5-ovalbumin using an ELISA previously described [1]. Hybridomas were cloned twice by limiting dilution in 96-well plates, using either peritoneal excudate cells as feeder cells (3)(4)(5)(6)(7)(8)(9)(10)(11) x 103 cells/well) or HECS (10% v/v). Positive clones were expanded and the cells were injected intraperitoneally into mice (0.7 x 106 cells) primed for 10 days with mineral oil.…”

“…Early in the immune response, a subset of the B cell clones present in the preimmune repertoire starts to proliferate and differentiate, in part due to the antigenic selection of complementary surface immunoglobulins. The isotype of the major fraction of these early synthesized antibodies is IgM, expressing variable regions containing relatively few mutations (2,3). At a later stage, when IgM has switched to IgG, somatic mutations appear to become the major source of variable region diversity i.e.…”

Common occurrence of an antiidiotypic antibody that recognizes T14+ anti‐DNA antibodies in patients with systemic lupus erythematosus

“…This region of the Ig molecule is solvent accessible (31) and immunodominant (28). In fact, it determines the Id of several murine antibodies, including those specific for phosphorylcholine (T15-t Id) (26), 4-hydroxy-3-nitro-5-iodophenylacetyl (NIP) (32), p-azophenylarsonate (33), and galactan (34). Interestingly, these 4 proteins share a common sequence, Tyr-Tyr-Gly, in the D segment, which in many cases is derived from the germline DFL16.1 gene (26,(32)(33)(34).…”

“…In fact, it determines the Id of several murine antibodies, including those specific for phosphorylcholine (T15-t Id) (26), 4-hydroxy-3-nitro-5-iodophenylacetyl (NIP) (32), p-azophenylarsonate (33), and galactan (34). Interestingly, these 4 proteins share a common sequence, Tyr-Tyr-Gly, in the D segment, which in many cases is derived from the germline DFL16.1 gene (26,(32)(33)(34). A change from glycine to arginine in a NIP protein destroyed the idiotype, but not the antigen-binding activity, of the protein (32), while the Tyr-Tyr-Gly-Ser-Ser sequence was found to be absolutely essential for the T15+ Id (26).…”