Localization and release of allergens from tapetum and pollen grains ofBetula pendula

Abstract

Summary.Although intact pollen grains are assumed to be the primary carrier of pollen allergens, specific immunoreactive components have been found in other aerosol fractions, e.g., starch grains and remains of tapetal cells Cryo-scanning-electron-microscopy results demonstrate the presence of a clear network of strands connecting the tapetum with the microspores. The distribution of protein in tapetal orbicules, pollen wall, and pollen cytoplasm was tested by histochemical stains for light microscopy and transmission electron microscopy. The protein is mainly localized at the apertures and starch grains in the cytoplasm of pollen and in the core and on the surface of tapetal orbicules. Monoclonal antibodies Bv-10, BIP3, and BIP4 have been used to locate the cellular sites of pollen and tapetal allergens in Betula pendula (syn. B. verrucosa). The application of rapid-freeze fixation prevented relocation of allergens from their native sites. The allergens are predominantly found in the starch grains and to lesser extent in the exine. We also tested interactions between mature birch pollen and human fluids: saliva, nostrils fluid, and eyes solution. The aim was to mimic more closely the in vivo situation during allergenic response. In all cases we observed several pollen grains that were burst and had released their cytoplasmic contents. In the nose the allergens are released from the pollen within minutes. In rhinitis, nasal pH is increased from the normal pH 6.0 to 8.0. When we used nasal fluid at pH 8.0, the number of ruptured pollen grains increased. The mechanism that might induce formation of small allergen-bearing particles from living plant cells is discussed.

Localisation of a carbohydrate epitope recognised by human IgE in pollen of Cupressaceae

“…In contrast, the finding that the callose vesicles did not have gold particles indicates that they do not behave like p-particles or starch granules, which in some species have been shown to possess strong allergenic activity (Grote et al 1994;El-Ghazaly et al 1999).…”

“…mAb 5E6+Hu-IgE), or incubated with mAb 4A6 alone (mAb 4A6), or pre-incubated with mAb 4A6 before Hu-IgE (Pr. mAb 4A6+Hu-IgE), or incubated with phosphate buffer (PB) alone (El-Ghazaly et al 1999), has recently been demonstrated and may explain the diffuse allergenic cross-reactivity among various allergens.…”

The combination of airborne pollen and allergen quantification to reliably assess the real pollinosis risk in different bioclimatic areas

“…Another possibility is that allergens could also be dispersed through the orbicules or Ubisch bodies from the anther wall, as well as through non-specific plant debris (Davis 1967;Pacini and Franchi 1993;D'Amato et al 2002;Vinckier and Smets 2001;Suárez-Cervera et al 2003, 2008a. The presence of labeled allergenic proteins in the orbicules was reported for Poaceae (El-Ghazaly et al 1999;Márquez et al 1997;Suárez-Cervera and SeoaneCamba 2005), Cupressaceae (Suárez-Cervera et al 2003, 2008a), Fraxinus (Rodriguez-Rajo et al 2010 and Parietaria. These orbicules are most likely involved in the dispersion of pollen grains, and they increase the allergen level in the air resulting in a higher risk of asthma.…”

Walls of allergenic pollen: Special reference to the endexine

“…In grass pollen, 11 groups of allergens have been described (Andersson & Lidholm, 2003;Petersen et al, 2006), eight to ten allergen groups were identified in Betula pendula Roth. (El-Ghazaly et al, 1999;Mothes et al, 2004), ten in Olea europaea L. pollen (Alche et al, 2004), six in the pollen of Ambrosia artemisiifolia L. (Wopfner et al, 2005) and Parietaria judaica L. pollen was shown to contain at least nine allergenic proteins (Asturias et al, 2003). Some protein groups are thereby more frequently recognized by IgE of sensitised individuals than others.…”