Allergen-Specific MHC Class II Tetramer+ Cells Are Detectable in Allergic, but Not in Nonallergic, Individuals

Abstract

Allergen-specific cells are present in very low frequency in peripheral blood of humans, and differ in function in allergic and nonallergic individuals. We report in this study that soluble class II MHC tetramers can be used to directly identify and study such allergen epitope-specific CD4+ T cells in humans. We identified the major antigenic epitope of rye grass allergen Lol p 1 in HLA-DRB1*0401 individuals using HLA-DR*0401 transgenic mice and peripheral blood cells from HLA-DR*0401 individuals. Using DRB1*0401 tetramers loaded with this major epitope of Lol p 1, we detected allergen-specific CD4+ T cells in the peripheral blood of DRB1*0401 rye grass allergic individuals after ex vivo expansion with allergen. These tetramer-positive cells produced IL-4, but little IFN-γ. In contrast, we were unable to detect rye grass tetramer-positive cells in cultures from HLA-DR*0401 nonallergic individuals, even after expansion with IL-2. Thus, our results suggest that rye grass allergen-specific T cells in DR*0401 nonallergic subjects are present at very low levels (e.g., because of deletion or suppression), differ in a fundamental way in their requirement for ex vivo expansion (e.g., they may be anergic), or use TCRs distinct from those of allergic individuals. Thus, analysis using DRB1*0401 tetramers loaded with a major epitope of Lol p 1 indicates that allergen-specific CD4+ T cells in nonallergic individuals are distinct from those in allergic subjects.

Assessment of Bet v 1-Specific CD4+ T Cell Responses in Allergic and Nonallergic Individuals Using MHC Class II Peptide Tetramers

“…Bet v 1-specific T cells isolated from BP allergic patients secrete, as expected, mostly IL-5 and IL-10, but not IFN-␥. These data are consistent with other studies (15,32,50,56), as well as with our analysis identifying predominantly Th2 clones in the peripheral blood of allergic patients (Table III) (12,30,50,51). The magnitude of the Th1 vs Treg cell response to Bet v 1 observed in the present study was unexpected, but it supports a predominant role of immune deviation toward IFN-␥ production to establish allergen-specific tolerance, as proposed recently by others (57).…”

“…Our results are in agreement with several studies demonstrating that healthy individuals can mount allergen-specific T cell responses (49 -52). In contrast, a recent study suggested that MHC class II peptide tetramers could detect T cell responses to the Lol p 1 grass pollen allergen in allergic but not in healthy individuals (15). Whereas it cannot be excluded that distinct seasonal allergens may elicit different types of immune responses, we can also possibly explain this discrepancy by the fact that we used in our study a potent in vitro stimulation protocol to expand rare allergen-specific T cell progenitors, relying on a Bet v 1 141-155 -Ii-Key conjugate peptide mix.…”

“…MHC class II peptide tetramer technology has been recently used succesfully in the field of allergy to characterize allergen-specific CD4 ϩ T cell responses (15)(16)(17). Soluble multimeric tetramers comprise fluorescently labeled recombinant MHC class II molecules, each bound to a high-affinity T cell epitope (18 -21).…”

Antigen-Specific CD4+T Cells Recognize Epitopes of Protective Antigen following Vaccination with an Anthrax Vaccine

“…In order to efficiently monitor this latter pathway, various lymphocyte activation assays have been used, often involving the activation or proliferation of CD4 ϩ T cells in vitro as an indirect measure of antigen-specific responses. With the development of pMHC class II tetramers, it is now possible to directly assay the CD4 ϩ T-cell population for antigen-specific phenotypes (2,3,7,(12)(13)(14)22).…”

Characterization of HLA Class II/Peptide-TCR Interactions of the Immunodominant T Cell Epitope in Art v 1, the Major Mugwort Pollen Allergen

“…However, in striking contrast to other allergens that contain multiple T cell epitopes (11)(12)(13), Art v 1 harbors only one single immunodominant epitope, Art v 1 [25][26][27][28][29][30][31][32][33][34][35][36] (KCIEWEKAQHGA), located in the defensin domain and recognized by 85% of Art v 1-reactive mugwort pollenallergic patients. The minimal epitope in Art v 1 [25][26][27][28][29][30][31][32][33][34][35][36] consists of 5-10 aa, and 3-5 aa within this core region have been shown to be relevant for T cell proliferation depending on the clonotypic TCR (14). The presentation of Art v 1 [25][26][27][28][29][30][31][32][33][34][35][36] has been shown to be HLA-DR-restricted (10,14).…”