t218 Virginia live oak

Unexpected exposure

The acorns are used for coffee, oil and food, and various parts of the tree have been used for medicinal purposes.

IgE-mediated reactions

Oak pollen is a major cause of asthma, allergic rhinitis and allergic conjunctivitis (1-4). Virginia live oak is not as common as White oak, but when it is grown in urban communities and near rural ones, it is an important allergen, and the prevalence of atopic sensitisation its pollen will be high.

Oak pollen affects sensitised individuals throughout the world. In Madrid, Spain, the highest level of airborne pollen from 1979 to 1993 was from the Quercus species (17%) (12), and in Salamanca, Spain, the highest quantity of pollen was from Holm oak (5). Oak pollen has also been shown to be significant in Zurich (6), Mexico City (15), Japan (16), Korea (17), Tampa, Florida (18), and Cape Town, South Africa (7).

Exposure to Oak dust may also lead to the development of sore throat and bronchial hyperresponsiveness (8).

Occupational asthma and rhinitis due to Oak wood dust have been demonstrated in wood workers (9-10).

Determination of IgE antibodies has been documented to be a useful investigation in the case of Oak-allergic individuals (11-12).

No allergens from this plant have yet been characterised.

As an extensive cross-reactivity among the different individual species of the genus could be expected (13), Virginia live oak may have allergens similar to those of White oak. Studies suggest that White oak pollen contains multiple proteins that are potentially allergenic (14). These include a group 1 Fagales protein, a calcium-binding protein and a profilin. See Oak tree t 7.

Moreover, probably not all species of Oak are equally allergenic:
Q. ilex pollen, although produced in considerable quantities, was not found to cause allergies in one study (15).

Cross Reactivity

Some of the pollen allergens in the various species of Oak cross-react with each other, while others are unique to their own species. No studies to date have examined the cross-reactivity between Virginia live oak and other plants, but assuming that an extensive cross-reactivity among the different individual species of the genus could be expected (13), studies involving White oak tree (Q. alba) are relevant.

In Sapporo, Japan, many Birch pollen-allergic patients complained of typical symptoms after the Birch pollen season. This has been attributed to Birch pollen-allergic individuals being affected by Oak pollinosis due to cross-reactivity between Birch and Oak pollen (16).

Natural Birch, Alder, Horn beam, Hazel, and Oak pollen contain allergens that share IgE epitopes with recombinant Bet v 1 and recombinant Bet v 2. A combination of recombinant Bet v 1 and Bet v 2 accounted for 82% of tree pollen-specific IgE in a study. Most of the tree pollen-specific IgE was directed against rBet v 1 (17).

In inhibitory ELISA assays, IgE binding to ginkgo pollen was inhibited more than 80% by Oak, Rye grass, Mugwort, and Ragweed; and 34% by Japanese Hop; and 10% by rBet v 2 at 10 µg/ml (18).

On the evidence of these studies, American patients allergic to Virginia live oak pollen can be expected to be affected by Oak species found in Europe and other parts of the world.

Last reviewed: May 2022