The major horse allergen Equ c 1 contains one immunodominant region of T cell epitopes.
BACKGROUND
Despite the fact that most significant mammalian respiratory allergens are lipocalin proteins, information on the human T cell reactivity to these allergenic proteins is largely missing.


OBJECTIVE
Knowing the T cell epitopes in allergens is a prerequisite for developing novel preparations for allergen immunotherapy.


METHODS
Specific T cell lines were generated with recombinant Equ c 1 from the peripheral blood mononuclear cells (PBMCs) of 10 horse-allergic subjects. For determining T cell epitopes, the lines were stimulated with 16mer synthetic Equ c 1 peptides overlapping by 14 amino acids. The binding capacity of Equ c 1 peptides to human leucocyte antigen class II molecules was determined by the competitive ELISA.


RESULTS
The major horse allergen Equ c 1 resembles two other lipocalin allergens, the major cow allergen Bos d 2 and the major dog allergen Can f 1, in that it is weakly stimulatory for the PBMCs of sensitized subjects. Moreover, the T cell epitopes of Equ c 1 are clustered in a few regions along the molecule, as is the case with Bos d 2 and Can f 1. Similar to Bos d 2, Equ c 1 contains one immunodominant epitope region at the carboxy-terminal end of the molecule. The T cell lines of eight horse-allergic subjects out of 10 showed strong reactivity to one or both of the two overlapping peptides, p143-158 and p145-160, in this region. The region probably contains two overlapping epitopes.


CONCLUSIONS
The 18mer peptide p143-160 from the immunodominant region of Equ c 1 is a potential candidate for the peptide-based immunotherapy of horse-sensitized subjects.
Immonen
A
A
Department of Clinical Microbiology, University of Kuopio, Kuopio, Finland. Anu.Immonen@uku.fi
Kinnunen
T
T
Sirven
P
P
Taivainen
A
A
Houitte
D
D
Peräsaari
J
J
Närvänen
A
A
Saarelainen
S
S
Rytkönen-Nissinen
M
M
Maillere
B
B
Virtanen
T
T
D000485:Allergens / Q000276:immunology / Q000494:pharmacology; D000818:Animals; D052179:Antigens, Plant; D002417:Cattle; D002460:Cell Line; D003429:Cross Reactions / Q000276:immunology; D004285:Dogs; D018984:Epitopes, T-Lymphocyte / Q000276:immunology* / Q000494:pharmacology / Q000627:therapeutic use; D006023:Glycoproteins / Q000276:immunology* / Q000494:pharmacology / Q000627:therapeutic use; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006736:Horses; D006801:Humans; D006967:Hypersensitivity / Q000188:drug therapy / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D054834:Lipocalins; D008297:Male; D010455:Peptides / Q000276:immunology* / Q000494:pharmacology / Q000627:therapeutic use; D011485:Protein Binding / Q000276:immunology
D000485:Allergens; D052179:Antigens, Plant; C113339:Bos d 2 allergen; D018984:Epitopes, T-Lymphocyte; C103025:Equ c1 allergen, Equus caballus; D006023:Glycoproteins; D000949:Histocompatibility Antigens Class II; D054834:Lipocalins; D010455:Peptides; C091462:allergen Can f I