An immunodominant DQ8 restricted gliadin peptide activates small intestinal immune response in in vitro cultured mucosa from HLA-DQ8 positive but not HLA-DQ8 negative coeliac patients.
BACKGROUND
Studies on intestinal T cell clones from the mucosa of patients with coeliac disease have led to the identification of immunogenic gliadin epitopes. One is HLA-DQ8 restricted, its recognition by T cells being increased by introduction of negatively charged residues operated by tissue transglutaminase.


OBJECTIVE
To test HLA-DQ8 restricted epitope in both native (QYPSGQGSFQPSQQNPQA) and deamidated (QYPSGEGSFQPSQENPQA) forms in an organ culture system of treated coeliac mucosa from HLA-DQ8 positive and HLA-DQ8 negative patients.


METHODS
Jejunal biopsies obtained from 10 patients with coeliac disease (six HLA-DQ8 positive and four HLA-DQ8 negative) were cultured in vitro with a peptic-tryptic digest (PT) of gliadin, or with the native (peptide A) or deamidated (peptide B) peptide. Intraepithelial CD3(+) and lamina propria total CD25(+) and CD3(+)CD25(+) cells were counted, lamina propria intercellular adhesion molecule 1 (ICAM-1) expression was evaluated, as well as that of Fas molecules on epithelial cells.


RESULTS
In HLA-DQ8 positive, but not in HLA-DQ8 negative, coeliacs the density of intraepithelial CD3(+) cells, lamina propria total CD25(+), and CD3(+)CD25(+) cells, as well as expression of ICAM-1 and Fas molecules were significantly increased in biopsies cultured with PT, peptide A, or peptide B compared with biopsies cultured in medium alone.


CONCLUSIONS
These data show that the DQ8 restricted gliadin peptide is immunogenic only in the intestinal mucosa of HLA-DQ8 positive coeliac patients in both native and deamidated forms.
Mazzarella
G
G
Institute of Food Science and Technology, CNR Avellino, Italy.
Maglio
M
M
Paparo
F
F
Nardone
G
G
Stefanile
R
R
Greco
L
L
van de Wal
Y
Y
Kooy
Y
Y
Koning
F
F
Auricchio
S
S
Troncone
R
R
D000293:Adolescent; D000328:Adult; D017252:CD3 Complex; D002446:Celiac Disease / Q000276:immunology*; D000939:Epitopes / Q000276:immunology*; D005260:Female; D005903:Gliadin / Q000276:immunology*; D006683:HLA-DQ Antigens / Q000276:immunology*; D006801:Humans; D016130:Immunophenotyping; D018799:Intercellular Adhesion Molecule-1 / Q000032:analysis; D007413:Intestinal Mucosa / Q000276:immunology*; D007583:Jejunum; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D009924:Organ Culture Techniques; D015375:Receptors, Interleukin-2; D018709:Statistics, Nonparametric; D013601:T-Lymphocytes / Q000276:immunology*; D019014:fas Receptor / Q000032:analysis
D017252:CD3 Complex; D000939:Epitopes; D006683:HLA-DQ Antigens; C109756:HLA-DQ8 antigen; D015375:Receptors, Interleukin-2; D019014:fas Receptor; D018799:Intercellular Adhesion Molecule-1; D005903:Gliadin