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Identification of the epitope recognized by the human V beta 5-specific monoclonal antibody 42/1C1. Potential
J Henwood1, J C Goodall, A W Boylston
1Department of Rheumatology, University of Birmingham, England.
Abstract:
A panel of T-cell clones was generated that was specific for amino acid residues 4-13 of the mycobacterial 65-kd stress protein. All the clones were found to express a member of the V beta 5 family, as defined by PCR. However, the clones could be differentiated on the basis of different staining characteristics with the mAb 42/1C1. This antibody is known to recognize both V beta 5.2 and V beta 5.3, as was the PCR primer pair used in the analysis. Sequencing of the TCRs revealed that those clones which were not stained by 42/1C1 expressed a previously unidentified member of the V beta 5 family. By comparing the sequences of the V beta 5 family members that are recognized by 42/1C1 with those that are not, we were able to identify a probable epitope for the antibody. It is also clear from our data that the TCRs of T cells recognizing identical MHC-peptide combinations, although very similar, may be differentiated by mAbs, thereby posing potential problems in any proposed disease therapy involving treatment with monoclonals.
Insights
Researchers identified a new T-cell receptor (TCR) variant recognizing mycobacterial stress protein. This discovery highlights challenges for monoclonal antibody therapies in treating diseases by differentiating similar TCRs.
Area of Science:
- Immunology
- Molecular Biology
- Microbiology
Background:
- T-cell receptors (TCRs) are crucial for adaptive immunity, recognizing specific peptide-MHC complexes.
- Mycobacterial 65-kd heat shock proteins are known antigens involved in immune responses.
- The V beta 5 family of TCRs plays a role in recognizing mycobacterial antigens.
Purpose of the Study:
- To characterize T-cell clones specific for the mycobacterial 65-kd stress protein.
- To investigate the diversity within the V beta 5 family of TCRs.
- To identify the epitope recognized by the monoclonal antibody (mAb) 42/1C1.
Main Methods:
- Generation of T-cell clones specific for residues 4-13 of the mycobacterial 65-kd stress protein.
- Polymerase Chain Reaction (PCR) to define V beta 5 family expression.
- Flow cytometry using mAb 42/1C1 for T-cell clone staining.
- TCR sequencing to identify novel V beta 5 family members.
Main Results:
- All generated T-cell clones expressed a V beta 5 family member.
- A subset of clones, not recognized by mAb 42/1C1, expressed a previously unidentified V beta 5 family member.
- Comparison of TCR sequences allowed identification of a probable epitope for mAb 42/1C1.
- Identical MHC-peptide recognition by T cells can involve highly similar, yet distinguishable, TCRs.
Conclusions:
- A novel V beta 5 family member and its corresponding TCRs were identified.
- The study identified a probable epitope for mAb 42/1C1, differentiating TCRs within the V beta 5 family.
- Subtle differences in TCRs recognizing the same antigen may complicate the use of monoclonal antibodies in disease therapy.