Study finds role of ligands in allergic sensitization phase

Researchers from Universidad Politécnica de Madrid (UPM) find direct evidence that the ligands, compounds carried by allergens, are actively involved in the allergic sensitization phase.

Researchers from Centre for Plant Biotechnology and Genomics (CBGP), a joint research centre of UPM and INIA, ha found that certain compounds carried by allergic proteins would be collaborating agents needed in the processes that trigger immune responses with the appearance of allergic symptoms.

This study was carried out by researchers from Mount Sinai Hospital in New York, Swiss Allergy Centre in Zurich and Institute of Applied Molecular Medicine of Universidad San Pablo CEU in Madrid. The obtained results will help develop preventive methods and effective treatments for allergies.

In spite of a great effort, fundamental questions on the molecular and immunological origin of allergies are still ignored. Many studies have sought solutions to an ancient enigma: why some proteins cause allergies despite being very similar to others that are harmless. Researchers achieved to identify the proteins which are common allergens are in pollen, mites, domestic animals, food…

Unfortunately, the characteristics of these proteins linked to allergens have been not found yet. However, in recent years a hypothesis developed in collaboration with the allergens group of CBGP has gained importance: certain compounds carried by the allergen proteins, known as ligands, would act as necessary collaborator agents in the allergic sensitization phase.

Pru p 3 was the protein selected for this study. This protein is responsible for the peach allergy, being very common in Mediterranean countries. The CBGP team has recently identified in a study the natural ligand of Pru p 3 as a compound formed by an alkaloid attached to a hydrocarbon tail. In the current study, the team has found direct evidence of the participation of the Pru p 3 ligand in the processes of the immune system recognition in the allergic sensitization phase.

Results reveal that the ligand is recognized by a type of cellular receptor called CD1d in the cell surface where the antigens appear, that is, substances able to provoke a response of the immune system to produce antibodies. The CD1d expressions are responsible for presenting lipid antigens activating cells of the immune system called iNKT (invariant natural killer T-cells). Once activated, these iNKT cells produce an enormous amount of substances that cause the characteristic symptoms of allergic disorders.

Since many allergens transport diverse compounds, the discovery of Pru p 3 lipid-ligand as an adjuvant to promote allergic sensitization through its recognition by CD1d expressions open new horizons. This new discovery could be a general essential feature of the mechanism underlying the phenomenon of allergenicity.

Allergies are a serious public health issue due to their high social and economic costs. Their prevalence has multiplied by 4 in the last 30 years and affects nearly 150 million citizens in the European Union, with a particular emphasis on the child population. Thus, the results of this work are especially significant: to reveal the role of the collaborators needed of the ligands will allow us to fully understand allergy causes and to know more about the development of new methods of diagnosis and therapy.