Grass-specific CD4(+) T-cells exhibit varying degrees of cross-reactivity, implications for allergen-specific immunotherapy.
BACKGROUND
Conceptually, allergic responses may involve cross-reactivity by antibodies or T-cells. While IgE cross-reactivity among grass-pollen allergens has been observed, cross-reactivity at the allergen-specific T-cell level has been less documented. Identification of the patterns of cross-reactivity may improve our understanding, allowing optimization of better immunotherapy strategies.


OBJECTIVE
We use Phleum pratense as model for the studying of cross-reactivity at the allergen-specific CD4(+) T cell level among DR04:01 restricted Pooideae grass-pollen T-cell epitopes.


METHODS
After in vitro culture of blood mono-nucleated cells from grass-pollen-allergic subjects with specific Pooideae antigenic epitopes, dual tetramer staining with APC-labelled DR04:01/Phleum pratense tetramers and PE-labelled DR04:01/Pooideae grass homolog tetramers was assessed to identify cross-reactivity among allergen-specific DR04:01-restricted T-cells in six subjects. Direct ex vivo staining enabled the comparison of frequency and phenotype of different Pooideae grass-pollen reactive T-cells. Intracellular cytokine staining (ICS) assays were also used to examine phenotypes of these T-cells.


RESULTS
T-cells with various degrees of cross-reactive profiles could be detected. Poa p 1 97-116 , Lol p 1 221-240 , Lol p 5a 199-218 , and Poa p 5a 199-218 were identified as minimally cross-reactive T-cell epitopes that do not show cross-reactivity to Phl p 1 and Phl p 5a epitopes. Ex vivo tetramer staining assays demonstrated T-cells that recognized these minimally cross-reactive T-cell epitopes are present in Grass-pollen-allergic subjects.


CONCLUSIONS
Our results suggest that not all Pooideae grass epitopes with sequence homology are cross-reactive. Non-cross-reactive T-cells with comparable frequency, phenotype and functionality to Phl p-specific T-cells suggest that a multiple allergen system should be considered for immunotherapy instead of a mono-allergen system.
Benaroya Research Institute at Virginia Mason, Seattle, WA, USA.
L D
LD
Archila
J H
JH
DeLong
E
E
Wambre
E A
EA
James
D M
DM
Robinson
W W
WW
Kwok
D000483:Alleles; D000485:Allergens / Q000276:immunology*; D000595:Amino Acid Sequence; D052179:Antigens, Plant / Q000737:chemistry / Q000276:immunology; D001491:Basophils / Q000276:immunology / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D003429:Cross Reactions / Q000276:immunology*; D016207:Cytokines / Q000378:metabolism; D003888:Desensitization, Immunologic; D018984:Epitopes, T-Lymphocyte / Q000737:chemistry / Q000276:immunology; D006680:HLA Antigens / Q000235:genetics / Q000276:immunology; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D006109:Poaceae / Q000276:immunology*; D011058:Pollen / Q000276:immunology; D037182:T-Cell Antigen Receptor Specificity / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism
D000485:Allergens; D052179:Antigens, Plant; D016207:Cytokines; D018984:Epitopes, T-Lymphocyte; D006680:HLA Antigens; D010455:Peptides; D007073:Immunoglobulin E
CD4+; MHC class II tetramers; Pooideae; T-cells; allergy; cross-reactivity; epitopes; grass-pollen