To estimate the minimal structural requirements for cross-reaction of idiotypic determinants, we determined the capacity of monoclonal antibodies specific for the idiotype of the phosphorylcholine (PC)-binding myeloma protein TEPC-15 for cross-reactivities with the PC-binding, acute-phase protein C-reactive protein (CRP) and the hemagglutinin from the horseshoe crab Limulus polyphemus (limulin), which binds sialic acid and PC. Certain monoclonal antibodies (MAb) to the TEPC-15 idiotype showed strong cross-reactions with CRP and limulin when tested by enzyme-linked immunoadsorbent assays. The specificity of the cross-reactivities was confirmed by testing the binding of the reactive anti-TEPC-15 MAb to both CRP and limulin in the presence of p-nitrophenylphosphorylcholine (pNPPC), N-acetylneuraminic acid, and bovine submaxillary mucin. The binding of the MAb to both CRP and limulin was strongly decreased by pNPPC, partially decreased by free PC, and not affected by N-acetylneuraminic acid or bovine submaxillary mucin. Neither CRP nor limulin showed significant overall sequence homology to vertebrate immunoglobulins. However, CRP, limulin, and TEPC-15 variable region heavy chain (VH) shared short stretches of homology (8-10 amino acids) that mapped to a stretch comprised of the second complementarity determining region and third framework region of the TEPC-15 VH. These results might reflect either evolutionary convergence forced upon molecules of diverse evolutionary histories because of steric requirements of binding the same ligand, or a conservation of primitive combining site gene segments in evolution.
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1 April 1984
Article|
April 01 1984
Invertebrate recognition protein cross-reacts with an immunoglobulin idiotype.
G R Vasta
J J Marchalonis
H Kohler
Online ISSN: 1540-9538
Print ISSN: 0022-1007
J Exp Med (1984) 159 (4): 1270–1276.
Citation
G R Vasta, J J Marchalonis, H Kohler; Invertebrate recognition protein cross-reacts with an immunoglobulin idiotype.. J Exp Med 1 April 1984; 159 (4): 1270–1276. doi: https://doi.org/10.1084/jem.159.4.1270
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