Specific immune response to Parietaria judaica plant profilin: a low T cell proliferative response supports high IgE and skin prick test

Strong and frequent T-cell responses to the minor allergen Phl p 12 in Spanish patients IgE-sensitized to Profilins

BACKGROUND

Profilins are dominant pan-allergens known to cause cross-sensitization, leading to clinical symptoms such as pollen-food syndrome. This study aimed to determine the T-cell response to Phl p 12 in profilin-sensitized patients, by measuring the prevalence, strength and cross-reactivity to clinically relevant profilins.

METHODS

The release of Phl p allergens from pollen was determined by mass spectrometry and immunochemistry. T-cell responses, epitope mapping and cross-reactivity to profilins (Phl p 12, Ole e 2, Bet v 2 and Mal d 4) were measured in vitro using PBMCs from 26 Spanish grass-allergic donors IgE-sensitized to profilin. Cross-reactivity was addressed in vivo using 2 different mouse strains (BALB/c and C3H).

RESULTS

Phl p 12 and Phl p 1 are released from pollen simultaneously and in similar amounts. Both T-cell response frequency (17/26 donors) and strength were comparable between Phl p 12 and Phl p 1. T-cell cross-reactivity to other profilins correlated with overall sequence homology, and 2 immunodominant epitope regions of Phl p 12 were identified. Data from mice immunized with Phl p 12 showed that cross-reactivity to Bet v 2 was mediated by conserved epitopes and further influenced by additional genetic factors, likely to be MHC II.

CONCLUSION

The strength, prevalence and cross-reactivity of T-cell responses towards Phl p 12 are comparable to the major allergen Phl p 1, which supports the hypothesis that T cells to Phl p 12 can play an important role in development of allergic symptoms, such as those associated with pollen-food syndrome.

Poor association of allergen-specific antibody, T- and B-cell responses revealed with recombinant allergens and a CFSE dilution-based assay

BACKGROUND

The adaptive immunity underlying allergy comprises two components, the allergen-specific antibody (i.e. IgE, IgG) and the T-cell response. These two components are responsible for different disease manifestations and can be targeted by different therapeutic approaches. Here, we investigated the association of allergen-specific antibody and T- as well as B-cell responses in pollen-allergic patients using recombinant (r) major birch pollen allergen rBet v 1 and major timothy grass pollen allergen rPhl p 5 as defined antigens.

METHODS

Allergen-specific IgE and IgG antibody responses were determined by ELISA, and allergen-specific T- and B-cell responses were measured in peripheral blood mononuclear cells using a carboxyfluorescein-diacetate-succinimidylester (CFSE) dilution assay.

RESULTS

CFSE staining in combination with T-cell- and B-cell-specific gating allowed discriminating between allergen-specific T-cell and B-cell responses. Interestingly, we identified patients where mainly T cells and others where mainly B cells proliferated in response to allergen stimulation. No association between the level of allergen-specific Ig responses and B- or T-cell proliferation was observed.

CONCLUSION

Purified recombinant allergens in conjunction with CFSE staining allow the dissection of allergen-specific B- and T-cell responses. The dissociation of allergen-specific antibody, and B- and T-cell responses may explain the occurrence of selective IgE- and T-cell-mediated manifestations of allergic inflammation and may be important for the development of diagnostic and therapeutic strategies selectively targeting B cells and T cells.

Allergens of weed pollen: an overview on recombinant and natural molecules

Weeds represent a botanically unrelated group of plants that usually lack commercial or aesthetical value. Pollen of allergenic weeds are able to trigger type I reactions in allergic patients and can be found in the plant families of Asteraceae, Amaranthaceae, Plantaginaceae, Urticaceae, and Euphorbiaceae. To date, 34 weed pollen allergens are listed in the IUIS allergen nomenclature database, which were physicochemically and immunologically characterized to varying degrees. Relevant allergens of weeds belong to the pectate lyase family, defensin-like family, Ole e 1-like family, non-specific lipid transfer protein 1 family and the pan-allergens profilin and polcalcins. This review provides an overview on weed pollen allergens primarily focusing on the molecular level. In particular, the characteristics and properties of purified recombinant allergens and hypoallergenic derivatives are described and their potential use in diagnosis and therapy of weed pollen allergy is discussed.

Correlation of Der p 2 T-cell responses with clinical characteristics of children allergic to house dust mite

BACKGROUND

An understanding of the mechanisms responsible for the development and maintenance of allergic inflammation and their clinical implications is needed to develop specific and successful treatment for allergy.

OBJECTIVES

To characterize in vitro T-cell responses to Der p 2, one of the major allergens of house dust mite (HDM), and investigate potential correlations between clinical and laboratory parameters.

METHODS

Forty-two patients monosensitized to HDM and 10 age-matched, healthy children were studied. Dendritic cells pulsed with Der p 2 were used to stimulate autologous CD14(-) cells. Der p 2-specific T-cell activation markers, proliferation, and cytokine production profiles were examined.

RESULTS

Der p 2-specific T-cell activation markers, proliferation, and T(H)2 cytokine production were significantly higher in HDM patients compared with healthy controls. Moreover, a significant correlation between proliferation and T(H)2 cytokine production was observed. Within the allergic group, skin reaction to HDM was significantly stronger in patients with a Der p 2-specific T-cell response. Levels of HDM-specific IgE directly correlated with interleukin 5 and interleukin 13 levels and with skin prick test results and, ultimately, with the patient's family history of allergy. Furthermore, the presence of atopic march correlated with T-cell proliferation.

CONCLUSION

We found that, in HDM patients, Der p 2-specific T(H)2 responses, promoted by autologous dendritic cells in vitro, correlate with clinical parameters.