Allergenic fragments of ryegrass (Lolium perenne) pollen allergen Lol p IV

The effect of geographical and climatic properties on grass pollen and Phl p 5 allergen release

The Poaceae family, including grasses, comprises several cosmopolitan and allergenic species. The aim of this study was to determine the correlations between Poaceae pollen and Phl p 5 allergen concentrations in two cities with different geographical and climatic properties in Turkey. Pollen were collected from Burkard traps in Ankara and Zonguldak. Phl p 5 sampling was carried out between March and October in both 2015 and 2016 using a BGI900 Cascade High Volume Air Sampler (900 L/min.). The concentrations of Phl p 5 were measured by the enzyme-linked immunosorbent assay (ELISA) technique. The annual sum of Poaceae pollen (pollen index) during 2015-2016 was 5454 in Ankara and 4142 in Zonguldak. The total Phl p 5 concentration was 1309 pg/m³ in Zonguldak, whereas it was 8181 pg/m³ in Ankara over 2 years. About 90% of the allergen was found in the fraction with particulate matter (PM) > 10 μm in both cities. It was found that the main meteorological parameter which affected pollen and Phl p 5 was temperature in both stations. Rainfall was also found to be important for Zonguldak, due to its climatic and geographic properties. Lastly, we suggest that the primary wind direction, which is from the south of Zonguldak, could have a 'drift effect' for allergens because of the airborne pollen concentrations and the dates on which the allergen is released into the atmosphere. The wind direction may be an important factor in the distribution of allergen and pollen grains in stations, especially those with a hilly topography.

Novel IgE recognized components of Lolium perenne pollen extract: comparative proteomics evaluation of allergic patients sensitization profiles

In the last years, proteomic investigation provided a powerful tool in molecular characterization of complex allergen sources with relevant implications in both diagnosis and immunotherapic treatment of allergies. We followed a proteomic approach to characterize ryegrass (Lolium perenne) pollen, a common cause of seasonal allergic diseases affecting an increasing part of world population. Peptide shotgun experiments performed on nanoLiquid Ultra Pressure Chromatography coupled with fast Q-TOF MS-MS/MS acquisition protocols (MS(E)) and 2-DE immunoblot combined with MALDI-TOF-TOF analysis allowed the detection of all previously identified ryegrass allergens. Comparative analysis of immunoblot highlighted a class of patients characterized by a more complex 2-DE pattern associated with increased levels of IgE antibodies and by higher susceptibility to multiple sensitization toward different allergen sources. Cluster analysis revealed that all these patients recognized profilin, considered the main cross-reactive allergen in grass pollen. Furthermore, mass spectrometry analysis revealed the presence of other IgE reactive components in ryegrass pollen that might be involved in polysensitization, such as cyclophilin, fructosyltransferase and legumin-like protein.

Primary structure, recombinant expression, and molecular characterization of Phl p 4, a major allergen of timothy grass (Phleum pratense)

Grass pollen allergy is one of the most important allergic diseases world-wide. Several meadow grasses, like timothy grass and rye grass, contribute to allergic sensitizations, but also allergens from extensively cultivated cereals, especially rye, make a profound contribution. The group 4 allergens are well known as important major allergens of grasses. We have cloned for the first time group 4 sequences from Phleum pratense, Lolium perenne, Secale cereale, Triticum aestivum, and Hordeum vulgare, and investigated the IgE-reactivity of recombinant Phl p 4 as a candidate for allergy diagnostic and therapeutic applications.

Purification, structural and immunological characterization of a timothy grass (Phleum pratense) pollen allergen, Phl p 4, with cross-reactive potential

Almost 500 million people worldwide suffer from Type I allergy, a genetically determined immunodisorder which is based on the production of IgE antibodies against per se harmless antigens (allergens). Due to their worldwide distribution and heavy pollen production, grasses represent a major allergen source for approximately 40% of allergic patients. We purified Phl p 4, a major timothy grass (Phleum pratense) pollen allergen with a molecular mass of 61.3 kDa and a pl of 9.6 to homogeneity. Circular dichroism spectroscopical analysis indicates that Phl p 4 contains a mixed alpha-helical/beta-pleated secondary structure and, unlike many other allergens, showed no reversible unfolding after thermal denaturation. We show that Phl p 4 is a major allergen which reacts with IgE antibodies of 75% of grass pollen allergic patients (n=150) and induces basophil histamine release as well as immediate type skin reactions in sensitized individuals. Phl p 4-specific IgE from three patients as well as two rabbit-anti Phl p 4 antisera cross-reacted with allergens present in pollen of trees, grasses, weeds as well as plant-derived food. Rabbit antibodies raised against Phl p 4 also inhibited the binding of allergic patients IgE to Phl p 4. Phl p 4 may thus be used for diagnosis and treatment of sensitized allergic patients.

Measurement of IgE antibodies against purified grass-pollen allergens (Phl p 1, 2, 3, 4, 5, 6, 7, 11, and 12) in sera of patients allergic to grass pollen

BACKGROUND

Current allergy diagnosis is performed with allergen extracts which contain a variety of allergenic and nonallergenic components. The availability of highly purified and well-characterized allergen molecules seems to be an advantage of component-based diagnosis.

METHODS

With the immunoenzymatic CAP FEIA System, we measured specific IgE levels to the recombinant allergens rPhl p 1, rPhl p 2, rPhl p 5, rPhl p 6, rPhl p 7, rPhl p 11, rPhl p 12, and native Phl p 4 in 77 sera of patients allergic to grass pollen, in order to evaluate the IgE-binding frequency to these purified grass-pollen allergens and their relationship to rBet v 4, rBet v 2, and other allergens.

RESULTS

The frequency of sensitization was as follows: rPhl p 1=93.5%; rPhl p 2=67.5%; rPhl p 5=72.7%; rPhl p 6=68.8%; rPhl p 7=7.8%; rPhl p 11=53.2%; rPhl p 12=35.1%; and native Phl p 4=88.3%. As expected, rPhl p 7 and rPhl p 12 had a very good correlation (Spearman's r) with Bet v 4 (r=0.95%, P<0.05) and rBet v 2 (r=0.99, P<0.05), respectively. Good correlations of rPhl p 12 with papain (r=0.93, P<0.05), latex (r=0.92, P<0.05), and bromelain (r=0.86, P<0.05) were found. Highly variable individual sensitization patterns were observed.

CONCLUSIONS

A new clinical approach has allowed the determination of specific allergograms for the different patients and may therefore be of great importance for more specific diagnosis. The use of component-resolved diagnostics may be useful to evaluate the allergen content of an extract for immunotherapy by monitoring patient's IgE and IgG directed to relevant allergens.

The high molecular mass allergen fraction of timothy grass pollen (Phleum pratense) between 50-60 kDa is comprised of two major allergens: Phl p 4 and Phl p 13

BACKGROUND

More than 70% of the patients allergic to grass pollen exhibit IgE-reactivity against the high molecular mass fraction between 50 and 60 kDa of timothy grass pollen extracts. One allergen from this fraction is Phl p 4 that has been described as a basic glycoprotein. A new 55/60 kDa allergen, Phl p 13, has recently been purified and characterized at the cDNA level.

OBJECTIVE

The relative importance of the two high molecular mass allergens has been characterized with respect to their IgE-binding frequency and capacity.

METHODS

Both high molecular mass allergens were biochemically purified and subjected to nitrocellulose strips. About 306 sera obtained from subjects allergic to grass pollens were used to determine specific IgE-binding frequency to Phl p 4 and Phl p 13. IgE-binding of allergens was quantified by ELISA measurements. Pre-adsorption of sera with purified allergens and subsequent incubation of nitrocellulose-blotted timothy grass pollen extract was performed to determine whether or not Phl p 4 and Phl p 13 represent the whole high molecular mass allergen fraction. Proteolytic stability of both allergens was investigated by addition of protease Glu-C.

RESULTS

More than 50% of 300 patients displayed IgE-binding with both allergens. Clear differences concerning the immunological properties of Phl p 4 and Phl p 13 were confirmed by individual IgE reactivities. Quantification of specific IgE for both allergens revealed comparable values. For complete inhibiton of IgE-binding in the high molecular mass range preincubation of sera with both allergens was necessary. Interestingly, inhibition of strong reacting sera with Phl p 13 eliminated not only reactivity of the 55/60 kDa double band, but in addition a 'background smear'. Whilst undenatured Phl p 4 was resistent to proteolytic digestion with Glu-C, native Phl p 13 was degraded rapidly.

CONCLUSION

Phl p 4 and Phl p 13 are immunologically different and must both be considered as major allergens. They are judged to be important candidates for potential recombinant therapeutics that may provide a basis for improved immunotherapy.

Subtribe-specific monoclonal antibodies to Lolium perenne

BACKGROUND AND OBJECTIVES

The ability to measure personal exposure to airborne grass pollen is important in the understanding of allergic diseases. Visual identification is time consuming and it is difficult to distinguish between many grass pollens morphologically. Although grass pollens share common allergenic determinants, we attempted to produce monoclonal antibodies that would distinguish between species, tribes and subfamilies of grasses which would allow immunodetection of pollens.

METHODS

Monoclonal antibodies raised against Lolium perenne were screened for specificity against an extended panel of grass pollen extracts using standard ELISA techniques and a novel particle blotting assay using whole pollen grains.

RESULTS

Antibodies showing specificity ranging from subfamily to part-tribe specificity were raised. The most specific monoclonal antibodies (numbers 4, 13 and 17) had reactivity to Lolium perenne and Festuca elatior but displayed little cross-reactivity to Phalaris arundinaceae and the rest of the Poeae tribe when tested by ELISA and no detectable cross-reaction when tested with particle blotting.

CONCLUSION

Monoclonal antibodies that are functionally specific to only two grasses can be produced and used to discriminate between related grass species.