Timothy grass rPhl p 1, g205
A new direction has emerged in the diagnosis of allergic reactions: Molecular diagnosis of allergies is a component allergy diagnosis.
The basis of molecular diagnosis of allergies is the identification of sensitization to allergens at the molecular level using natural, highly purified and recombinant allergen molecules, that is, their components, and not extracts. In the late 1980s, when DNA technology began to be introduced, allergen molecules were characterized and cloned, which helped identify antigenic determinants in various allergic diseases. All this played an important role in the emergence of a new type of diagnostics - molecular diagnostics, which, in turn, contributed to the development of more effective treatment for allergies. Determination of antibodies to recombinant allergens makes it possible to identify the leading component in the composition of complex allergens at the level of molecular allergology. This allows you to differentiate true and cross allergies. The use of recombinant allergens represents a new tool in the diagnosis of type I allergic reactions, which allows one to obtain detailed information about the patient’s sensitization, cross-reactivity with other allergens, justify the feasibility and predict the effectiveness of allergen-specific immunotherapy (ASIT).
This direction will change views on the examination and treatment of patients and bring them into line with those in world medicine.
There are 3 main advantages of performing this study:
- Molecular allergy diagnostics makes it possible to differentiate true sensitization from sensitization due to cross-reactivity. This data will help determine the sources of allergies: one single one, several closely related ones, or many different ones.
- Molecular allergy diagnostics will eliminate the need for provocative tests and make it possible to give clearer recommendations regarding eliminating contact with allergens.
- Molecular allergy diagnostics is necessary in the selection of allergen-specific immunotherapy (ASIT); in individuals with polyvalent sensitization, the most accurate way to determine the most important allergen for which ASIT will be performed. It has been shown that the use of molecular diagnostic methods forces a change in ASIT, selected based on the results of skin prick tests.
In order to begin using allergen components and correctly interpret research results, you need to know basic information about allergen components and their clinical use:
Allergen molecules are given a name, first the first three letters of the Latin name of the genus, then the first letter of the species and an Arabic numeral - the allergen number (the number depends on the order of isolation and/or clinical importance).For example: Birch – Bet v 1, Bet v 2, etc.
The composition of an allergenic substance includes not one, but several protein components that can act as allergens: “major” - the main allergens, others “minor” - minor.
Major allergenic components are allergenic molecules to which antibodies are found in more than half - 50% of patients in the population reacting to a given source. They are heat resistant and more immunogenic. Large in size and contained in this allergen in larger quantities.
Minor molecules are smaller in size and less immunogenic allergenic molecules, which are usually contained in smaller quantities in the allergen, but are present in many different allergens, sometimes not closely related, providing cross-allergy. That is, allergens with a prevalence of more than 50% are called major, and less than 10% are called minor.
The culprits of allergies include grasses and trees. One of the representatives of herbs is timothy grass.
Timothy grass (Latin name Phleumpratense) belongs to the herbs of the grass family, widespread throughout the world. Timothy is a winter-hardy plant and begins to bloom in early spring. Timothy grass pollen can cause allergic diseases. Symptoms of allergic reactions to timothy pollen include redness and burning of the eyes, watery eyes, swelling of the eyelids, nasal congestion, sneezing, coughing, shortness of breath and bronchospasm.
To determine sensitization to timothy grass, as a complex allergen, the following are studied: Phl p 1 and Phl p 5b are the main “major” allergens, Phl p 7 and Phl p 12 are the secondary “minor” ones.
Phl p 1 is a glycosylated protein, the main (“major”) timothy allergen, specific IgE antibodies to which are detected in 95% of patients with allergies to pollen of various types of meadow grasses.
Phl p 5b is the main and one of the most reactive timothy allergens, which provokes symptoms of allergic rhinitis and bronchial asthma in sensitized patients. IgE antibodies to this allergen are detected in 65-90% of people allergic to meadow grass pollen.
Phl p 7 is a calcium-binding protein and a minor timothy pollen allergen. It is detected in 10-15% of patients sensitized to meadow grass pollen and causes cross-reactivity with many plants (birch, alder, olive, weeds and others).
Phl p 12 is a protein from the profilin group, a minor allergen of timothy grass. Antibodies of the IgE class are detected in 15-30% of patients with an allergy to meadow grass pollen. Timothy grass profile proteins have a similar structure to those found in many plant species, plant foods, and latex.
A true allergy to timothy pollen is confirmed by the presence in the blood of specific IgE antibodies to the main allergic components Phl p 1, Phl p 5b, and the presence of reagin antibodies only to secondary (“minor”) allergic components (Phl p 7, Phl p 12) indicates cross-sensitization with others plant allergens.