The Journal of Immunology, Vol 150, Issue 3 880-887, Copyright © 1993 by American Association of Immunologists

ARTICLES

Lack of promiscuity in autoantigen-specific H and L chain combinations as revealed by human H and L chain "roulette"

S Portolano, GD Chazenbalk, JS Hutchison, SM McLachlan and B Rapoport
Thyroid Molecular Biology Unit, Veterans' Administration Medical Center, San Francisco, CA 94121.

Individual H or L chains from a human autoantibody were used to search for other L or H chains that could form antigen-binding fragments, Fab, with the same specificity. The parent Fab (SP1.2) exhibits high affinity binding for thyroid peroxidase (TPO), a 107-kDa protein that is the major autoantigen in human autoimmune thyroiditis. This autoantibody "roulette," performed by using Ig H and L chain gene libraries expressed in bacteria, increased the frequency of TPO-binding clones in the new libraries. However, the frequency was still much lower than would be the case if promiscuous combinations with a variety of H or L chains were compatible with specific Ag binding. Nucleotide sequence analysis of the H and L chains of the new TPO-binding clones revealed even more restriction. Thus, with the SP1.2 H chain, all 11 new Fab utilized L chains from the same V kappa 1 family germline gene as SP1.2 itself. Similarly, five of six H chains "captured" by the SP1.2 L chain were very closely related to the SP1.2 H chain. However, one totally different H chain was isolated: SP4.6 has a VH region that differs substantially from that of SP1.2. SP4.6 also has a distinct D region, uses a different JH, and, unlike SP1.2, which is an IgG1, belongs to subclass IgG4. The affinities for TPO of SP4.6 (with the different H chain) and SP1.20 (which had the least mutated L chain germline gene) were similar to that of SP1.2 (approximately 10(-10) M). As expected, the SP1.2 and SP1.20 Fab, which have the same H chain and closely related L chains, bound to the same domain on TPO. However, a similar domain on TPO was recognized by both SP4.6 and SP1.2, despite the fact that their V, D, and J regions are quite different. This observation raises the possibility that the L chain is critical in defining epitope specificity, even in the presence of completely different D regions and nonidentical VH regions.

This article has been cited by other articles:

				M. M. Uttenreuther-Fischer, J. A. Kruger, and P. Fischer Molecular Characterization of the Anti-Idiotypic Immune Response of a Relapse-Free Neuroblastoma Patient following Antibody Therapy: A Possible Vaccine against Tumors of Neuroectodermal Origin? J. Immunol., June 15, 2006; 176(12): 7775 - 7786. [Abstract] [Full Text] [PDF]

				F. Latrofa, P. Pichurin, J. Guo, B. Rapoport, and S. M. McLachlan Thyroglobulin-Thyroperoxidase Autoantibodies Are Polyreactive, Not Bispecific: Analysis Using Human Monoclonal Autoantibodies J. Clin. Endocrinol. Metab., January 1, 2003; 88(1): 371 - 378. [Abstract] [Full Text] [PDF]

				N. Chapal, T. Chardes, D. Bresson, M. Pugniere, J.-C. Mani, B. Pau, M. Bouanani, and S. Peraldi-Roux Thyroid Peroxidase Autoantibodies Obtained from Random Single Chain Fv Libraries Contain the Same Heavy/Light Chain Combinations as Occur in Vivo Endocrinology, November 1, 2001; 142(11): 4740 - 4750. [Abstract] [Full Text] [PDF]

				M. Czerwinski, D. Siemaszko, D. L. Siegel, and S. L. Spitalnik Only Selected Light Chains Combine with a Given Heavy Chain to Confer Specificity for a Model Glycopeptide Antigen J. Immunol., May 1, 1998; 160(9): 4406 - 4417. [Abstract] [Full Text] [PDF]

				S. Chacko, E. A. Padlan, S. Portolano, S. M. McLachlan, and B. Rapoport Structural Studies of Human Autoantibodies J. Biol. Chem., May 24, 1996; 271(21): 12191 - 12198. [Abstract] [Full Text] [PDF]