Basic isoforms of Par o 1, the major allergen of Parietaria officinalis pollen

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.

Immunology

The concept of forbidden foods that should not be eaten goes back to the Garden of Eden and apart from its religious meanings it may also have foreshadowed the concept of foods that can provoke adverse reactions. Thus we could say that allergic diseases have plagued mankind since the beginning of life on earth. The prophet Job was affected by a condition that following the rare symptoms described by the Holy Bible might be identified as a severe form of atopic dermatitis (AD). The earliest record of an apparently allergic reaction is 2621 B.C., when death from stinging insects was first described by hieroglyphics carved into the walls of the tomb of Pharaoh Menes depicting his death following the sting of a wasp. In 79 A.D., the death of the Roman admiral Pliny the Elder was ascribed to the SO₂-rich gases emanating from the eruption of Mount Vesuvius. Hippocrates (460–377 B.C.) was probably the first to describe how cow’s milk (CM) could cause gastric upset and hives, proposing dietetic measures including both treatment and prevention for CM allergy.

Influence of both TCR repertoire and severity of the atopic status on the cytokine secretion profile of Parietaria officinalis-specific T cells

Peripheral blood mononuclear cells (PBMC) from both nonatopic and Parietaria officinalis-sensitive donors proliferated in response to the allergen Par o 1 and developed into Par o 1-specific T cell lines and clones, which also showed reactivity for Par o 1-derived peptides. Virtually all Par o 1-specific T cell lines and large numbers of Par o 1-specific T cell clones proliferated in response to two Par o 1 nonapeptides (p92 and p96), which probably contain immunodominant epitopes of the Par o 1 allergen. Both p92- and p96-specific T cell clones showed the ability to produce IFN-gamma, but p92-specific T cell clones produced significantly lower amounts of IL-4 and IL-5 than p96-specific T cell clones, indicating that distinct epitopes, able to elicit functionally different T helper cell responses, may coexist in Par o 1. However, p92-specific T cell clones derived from atopic subjects with high IgE serum levels (high IgE producers) secreted significantly higher amounts of IL-4 and IL-5 than corresponding T cell clones generated from nonatopic subjects or patients with low IgE serum levels (low IgE producers), whereas p96-specific T cell clones secreted high IL-4 and IL-5 concentrations irrespective of whether they derived from high or low IgE producers. The addition of IL-4 and anti-IL-12 mAb to bulk culture significantly up-regulated the development of p92-specific T cells into IL-4-producing cells, whereas the addition of IL-12 and anti-IL-4 mAb shifted the differentiation of p96-specific T cells towards IFN-gamma-producing cells. Taken together, these results suggest that the cytokine profile of allergen-specific T cells is influenced by both the T cell receptor repertoire and the severity of atopic status and can be modulated, at least in vitro, by stimulation with the specific peptide in the presence, or after removal, of appropriate cytokines.