Ability of pollen cytoplasmic granules to induce biased allergic responses in a rat model.
BACKGROUND
Grass pollen is one of the most important aeroallergens in Europe. It highly contributes to respiratory allergic diseases, mainly allergic rhinitis. In contact to water or airborne pollutants, pollen grains can release pollen cytoplasmic granules (PCGs) containing allergens. Because of their size (<5 μm), PCGs may penetrate deeper into the lungs to induce higher allergic responses, such as asthma. They have been associated with thunderstorm-related asthma. The aim of this study was to evaluate, with Brown Norway rats, the allergenic potential of isolated PCGs and to compare it with the allergenicity of whole timothy grass pollen.


METHODS
Rats were sensitized (day 0) and challenged (day 21), in controlled comparative conditions, with pollen grains (0.5 mg) or PCGs (4.5 × 10⁷ and 0.5 mg). At day 25, blood samples, bronchoalveolar lavage fluid (BALF) and bronchial lymph node were collected. IgE and IgG1 levels in sera were assessed by ELISA. Alveolar cells, protein and cytokine concentrations were quantified in BALF. T cell proliferation, in response to pollen or granules, was performed by lymph node assay.


RESULTS
The results showed that proliferative responses of lymph node cells were similar in PCG- and pollen-sensitized rats. IgE and IgG1 levels were higher in pollen- than in PCG-sensitized rats. However, eosinophils, lymphocytes and pro-allergy cytokines in BALF were higher in PCG- than in pollen-sensitized rats.


CONCLUSIONS
Thus, PCGs, able to deeply penetrate in the respiratory tract, induced local and strong allergic and inflammatory responses more linked with asthma- than rhinitis-related allergic symptoms.
Abou Chakra
Oussama
O
ESPCI, UMR 7195 - PECSA, LECA, Paris, France. oussama.abou-chakra@espci.fr
Rogerieux
Françoise
F
Poncet
Pascal
P
Sutra
Jean-Pierre
JP
Peltre
Gabriel
G
Sénéchal
Hélène
H
Lacroix
Ghislaine
G
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D016207:Cytokines / Q000276:immunology; D003594:Cytoplasmic Granules / Q000276:immunology*; D004195:Disease Models, Animal; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D008297:Male; D011058:Pollen / Q000276:immunology*; D011897:Random Allocation; D051381:Rats; D012130:Respiratory Hypersensitivity / Q000276:immunology*; D018709:Statistics, Nonparametric
D016207:Cytokines; D007074:Immunoglobulin G; D007073:Immunoglobulin E