The Regions on the Light Chain of Botulinum Neurotoxin Type A Recognized by T Cells from Toxin-Treated Cervical Dystonia Patients. The Complete Human T-Cell Recognition Map of the Toxin Molecule

ABSTRACT

We have recently mapped the in vitro proliferative responses of T cells from botulinum neurotoxin type A (BoNT/A)-treated cervical dystonia (CD) patients with overlapping peptides encompassing BoNT/A heavy chain (residues 449–1296). In the present study, we determined the recognition profiles, by peripheral blood lymphocytes (PBL) from the same set of patients, of BoNT/A light (L) chain (residues 1–453) by using 32 synthetic overlapping peptides that encompassed the entire L chain. Profiles of the T-cell responses (expressed in stimulation index, SI; Z score based on transformed SI) to the peptides varied among the patients. Samples from 14 patients treated solely with BoNT/A recognized 3–13 (average 7.2) peptides/sample at Z > 3.0 level. Two peptide regions representing residues 113–131 and 225–243 were recognized by around 40% of these patients. Regarding treatment parameters, treatment history with current BOTOX^® only group produced significantly lower average T-cell responses to the 32 L-chain peptides compared to treatments with mix of type A including original and current BOTOX^®. Influence of other treatment parameters on T-cell recognition of the L-chain peptides was also observed. Results of the submolecular T-cell recognition of the L chain are compared to those of the H chain and the T-cell recognition profile of the entire BoNT/A molecule is discussed.

Abbreviations used: BoNT/A, botulinum neurotoxin type A; BoNT/A_i, inactivated BoNT/A; BoNT/B, botulinum neurotoxin type B; CD, cervical dystonia; L chain, the light chain (residues 1–448) of BoNT/A; LNC, lymph node cells; H chain, the heavy chain (residues 449–1296) of BoNT/A; H_C, C-terminal domain (residues 855–1296) of H chain; H_N, N-terminal domain (residues 449–859) of H chain; MPA, mouse protection assay; SI, stimulation index (SI = cpm of ³H-thymidine incorporated by antigen-stimulated T cells/cpm incorporated by unstimulated cells); TeNT, tetanus neurotoxin; TeNT_i, inactivated TeNT.

KEYWORDS:

• Botulinum neurotoxin type A
• cervical dystonia
• light chain
• MHC control
• synthetic peptides
• T-cell epitopes

Acknowledgments

We thank Karen Flores and Jake Keller for their able technical assistance.

Declaration of interest

The authors report no conflict of interest.

Funding

This work was supported by an unrestricted grant from Allergan and by the Welch Foundation (Grant Q007) and the award to M.Z.A. of the Robert A. Welch Chair of Chemistry.

Additional information

Funding

This work was supported by an unrestricted grant from Allergan and by the Welch Foundation (Grant Q007) and the award to M.Z.A. of the Robert A. Welch Chair of Chemistry.