BETV4

Polcalcin Bet v 4 is a protein with a molecular weight of approximately 9.3 kDa . It contains two EF-hand motifs, which are helix-loop-helix structural domains capable of binding calcium ions. This calcium-binding property is crucial for the protein’s stability and function.

Bet v 4 is considered a minor allergen because it is recognized by the immune system of a smaller percentage of individuals allergic to birch pollen. Studies have shown that about 20% of patients allergic to birch pollen have specific IgE antibodies against Bet v 4 . Despite being a minor allergen, Bet v 4 plays a significant role in the diagnosis and management of birch pollen allergies.

Recombinant Bet v 4 is produced using genetic engineering techniques. The gene encoding Bet v 4 is cloned and expressed in a suitable host organism, such as Escherichia coli . The recombinant protein is then purified, often using immobilized metal affinity chromatography, to achieve high purity levels suitable for research and diagnostic applications .

Recombinant Bet v 4 is primarily used in allergen-specific IgE antibody testing. It helps in the diagnosis of birch pollen allergies and can be used to identify individuals who are polysensitized to multiple pollen allergens . The recombinant form of Bet v 4 is also valuable in research studies aimed at understanding the molecular mechanisms of allergic reactions and developing new therapeutic approaches.

The prevalence of sensitization to Bet v 4 varies geographically. For instance, studies have reported that 5% of individuals in Finland, 8% in Sweden, 11% in Austria, 6% in France, 27% in Italy, and 7% in Switzerland have specific IgE antibodies against Bet v 4 . In Japan, only 2.5% of birch-allergic individuals were found to have IgE antibodies against Bet v 4 .

Polcalcin Bet v 4 is known to be highly cross-reactive with other polcalcins found in different pollen species. This cross-reactivity can lead to polysensitization, where individuals are allergic to multiple pollen types. For example, polcalcins from timothy grass (Phl p 7) and alder (Aln g 4) can also trigger allergic reactions in individuals sensitized to Bet v 4 .