Pollen Allergy: What It Is and How It Develops

Pollen allergies, also known as pollinosis, are a common type of seasonal allergic reaction. This hypersensitivity reaction of the immune system is triggered by the inhalation of pollen grains produced by plants.

What are Pollens?

Pollens are essentially the male reproductive cells, or gametophytes, produced by plants during their flowering stage. These grains are microscopic and lightweight, varying in shape depending on the plant species. Their primary function is to fertilize other plants of the same species.

How Does Pollen Allergy Develop?

Pollen contains unique substances known as antigens, which can "sensitize" genetically predisposed individuals. In an allergic individual, these substances are released at the respiratory mucous membranes and can trigger an excessive reaction of the immune system. The immune system is stimulated to produce specific antibodies, known as class E immunoglobulins (IgE).

The intervention of IgE results in the release of chemical mediators of inflammation such as histamine, prostaglandins, leukotrienes, bradykinin, and others. These substances trigger an inflammatory process by dilating the capillary vessels and drawing specific defense cells from the blood and tissues to participate in the reaction. The end result is the manifestation of typical symptoms of pollen allergy.

It's important to note that not all plants release pollen capable of inducing an allergic reaction, and typically, a person is allergic to only certain allergens. Furthermore, pollen allergy only occurs when the concentration of pollen in the atmosphere reaches a certain threshold.

How Does Pollen Spread?

To reproduce, plants produce pollen. These cells contain male gametes responsible for fertilizing the female seed. Pollens are typically divided into two categories:

1. Wind-transported
   These are the majority of pollens with allergological importance. These plants rely on the wind to spread their pollen grains, which are produced in large quantities to fertilize the female gametes of the same species, even at considerable distances.
2. Insect-transported
   The pollen from these plants is released in small quantities and transported by insects to another flower of the same species. These pollen grains have little allergological importance as they are poorly concentrated in the atmosphere.

Factors Affecting Pollination

The release of pollen is related to the flowering period, which varies for each species. The quality and quantity of the various types of allergenic granules present in the air depend on several factors, including:

• The presence and distribution of different plant types in a specific area.
• The shape and size of the pollen, which influence its ability to be airborne.
• The presence of components capable of acting as allergens and stimulating the immune system of allergic subjects to produce specific IgE antibodies.
• Climatic and meteorological conditions, these influence the air dispersion and atmospheric concentration of pollen once pollination has begun.