What causes the hay fever in children?

In the etiology of pollinosis in children, according to the researchers, the leading role is played by pollen of cereal grasses, the sensitivity to which is found in 75% of the examined, somewhat less frequently, but often enough - pollen of trees (in 56% of patients) and in 27% of children is sensitized to pollen of weeds (wormwood, quinoa). In 64% of children with pollinosis, the disease develops as a result of polyvalent allergies.

Allergens of pollen of plants refer to aeroallergens. Of the many thousands of plants on Earth, only about 50 produce pollen responsible for the occurrence of pollinosis. Male genital elements in mainly wind-polluted plants cause sensitization. The grains of these pollen species have a rounded shape and a diameter of not more than 35 μm. Sensitization in each geographical area occurs to the pollen of widespread plants that produce a huge amount of pollen (one ragweed bush allocates up to 1 million pollen grains per day).

There are three main groups of allergenic plants:

• wood;
• cereals;
• motley grass (weeds).

The first spring peak of a high density of pollen allergies (April-May) causes pollen of trees: hazel, alder, oak, birch, ash, nut, poplar, maple, etc. The role of pollen of pine and spruce in the occurrence of allergic diseases of the respiratory tract is low.

The second summer rise in pollen concentration (June-August) is associated with the flowering of grasses: bluegrass, grasshopper, fire, fescue, hedgehog, foxtail, rye, maize, etc. The flowering season of these herbs coincides with the high concentration of poplar fluff in the air, which is often mistaken for patients for reaction to fluff.

The third autumn peak of pollen allergy (August-October) is caused by plants with the greatest allergenic activity. These include weeds: ambrosia, quinoa, dandelion, hemp, nettle, wormwood, buttercup, etc.

Most pollen is thrown out by plants in the morning hours (from sunrise to 9 am); maximum concentration - in dry windy weather.

Immunological status of children with pollinosis is characterized by a high content of reactans: a high level of total IgE and specific IgE, especially during flowering periods.

Allergic inflammation simultaneously affects the mucous membranes of the eye and nose (rhinoconjunctivitis), nose and paranasal sinuses (rhinosinusitis), nose and nasopharynx (nasopharyngitis), trachea and bronchi (rhinotraheobronchitis).

According to observations of many authors, pollinosis in children less than 3 years of age is less common, in subsequent ages the frequency of sensitization to pollen of plants increases and reaches a maximum by school age. The age of the first manifestations of pollinosis in children was 3 years.

Factors predisposing to pollinosis are:

• deficiency of secretory IgA;
• instability of cell membranes of macrophages and granulocytes;
• decrease in the production of a substance that inhibits the activity of the pollen permeability factor,
• respiratory infections;
• Environmental pollution of the atmosphere, violating mucociliary clearance.

The pathological stage of the lesion is accompanied by degranulation of the mast cells of the mucous membranes of the eyes, respiratory tracts with the release of a large amount of histamine and other biogenic amines. In some patients with pollinosis, immunocomplex mechanisms play an active role in pathogenesis.