Interaction among human leucocyte antigen-peptide-T cell receptor complexes in cow's milk allergy: the significance of human leucocyte antigen and T cell receptor-complementarity determining region 3 loops.
BACKGROUND
Allergic individuals respond to only a few specific antigens, therefore allergic diseases are characterized by antigen specificity. Clarification of the mechanism of antigen specificity will lead to progress in the therapy of allergic diseases.


OBJECTIVE
The purpose of this study is to determine the specific association among T cell epitopes, antigen-presenting molecules and T cell receptor (TCR), and to determine the TCR usage in the pathogenesis of allergies using antigen-specific T cell clones (TCCs). The results can clarify the mechanism of the antigen specificity of allergic diseases, and provide new therapeutic possibilities using analogue peptides.


METHODS
Short-term T cell clones specific to beta-lactoglobulin (BLG) were established from peripheral blood mononuclear cells (PBMCs) collected from five patients allergic to cow's milk. We then identified the T cell epitopes and antigen-presenting molecules, and examined TCR usage. We also determined the sequence of the TCR-complementarity-determining region 3 (CDR3).


RESULTS
Six TCCs established from the five patients recognized three different peptides, and BLGp97-117 was recognized by four of the six TCCs. BLGp101-112 (KYLLFCMENSAE) was the core sequence in the fragment. Sequence analysis of TCR by the RT-PCR method revealed a marked heterogeneity in TCR usage, and similar amino acid sequences were recognized in the CDR3 region. Four of the six TCCs recognized BLG in association with human leucocyte antigen (HLA)-DRB1*0405 as antigen-presenting molecules.


CONCLUSIONS
We proposed the motif of the interaction between the HLA-DRB1*0405 allele and antigen peptide, and suggested that HLA-DRB1*0405 is an immunoregulatory gene product for T cell responses to BLG.
Sakaguchi
H
H
Department of Pediatrics, Gifu University School of Medicine, Japan. heima@kd6.so-net.ne.jp
Inoue
R
R
Kaneko
H
H
Watanabe
M
M
Suzuki
K
K
Kato
Z
Z
Matsushita
S
S
Kondo
N
N
D000483:Alleles; D000818:Animals; D002999:Clone Cells / Q000737:chemistry; D022801:Complementarity Determining Regions / Q000276:immunology; D018604:Epitope Mapping; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D006680:HLA Antigens / Q000494:pharmacology*; D006684:HLA-DR Antigens / Q000235:genetics; D059811:HLA-DRB1 Chains; D006801:Humans; D007782:Lactoglobulins / Q000276:immunology; D016269:Milk Hypersensitivity / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D010455:Peptides / Q000494:pharmacology*; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000502:physiology*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics
D022801:Complementarity Determining Regions; D018984:Epitopes, T-Lymphocyte; D006680:HLA Antigens; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; D007782:Lactoglobulins; D010455:Peptides; D011948:Receptors, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta