w17 Firebush (Kochia)

IgE mediated reactions

Anecdotal evidence suggests that asthma, allergic rhinitis and allergic conjunctivitis are common following exposure to pollen from Kochia; however, few specific studies have been reported to date. (1-3)

In one study in Thailand, Kochia was shown to be the second most important weed aeroallergen, with 14% of 100 patients with allergic rhinitis sensitised to it. (1)

In a study in the Midwestern USA, evaluating the frequency of sensitisation to cannabis pollen, found that 61% were skin prick positive for cannabis and all subjects were also skin test positive to weeds pollinating during the same period: Ragweed, Pigweed, Cocklebur, Russian thistle, Marsh elder, and Kochia. (4)

Among 1,159 patients attending an allergy clinic in Saudi Arabia, 51% of Saudi Arab patients and 28% of North American expatriates living in the area were sensitised to Kochia. This weed’s pollen was the 2 (nd) and 7 (th) most prevalent allergen sensitising the respective groups.(3)

Kochia pollen is also common in Tehran, Iran, (5) and a common cause of sensitisation in St. Louis, Missouri, USA. (6)

Of 327 adult patients with respiratory, dermatologic and ophthalmologic diseases of suspected allergic origin who attended a Hospital based in the United Arab Emirates, skin prick tests found that 244 patients (74.6%) were sensitised to at least one allergen. The twelve most common allergens were: Mesquite (45.5%), Grass Mix (40.7%), Cottonwood (33.1%), Bermuda grass (31.3%), Kochia (25.8%), Acacia (25.6%), Alfalfa (22.9%), Chenopodium (19.6%), Date palm (13.8%), Cockroach (14.7%), house dust (11.9%) and dust mite (9.5%). (2)

No allergens from this plant have yet been characterised.

In a study of sera from 20 US donors with a positive clinical history and strong skin prick test to Salp pollen extract (Salsola pestifer/ Russian thistle / saltwort), Koc s contained one major and four minor allergens of which proteins of 35 and 55 kDa were suggested to be important allergens. (7)

In a study of Iranian allergic patients sensitised to Amaranthus retroflexus (Common pigweed) pollen, several allergenic components (85, 45, 39, 18, 15, and 10 kDa) of the A. retroflexus pollen extract were recognised in patients' sera and the IgE reactivity of the pollen extract was partially inhibited by Chenopodium album, K. scoparia, and Salsola kali. Three proteins (39, 45, and 66 kDa) were suggested as the common allergenic components among the pollens. (8)

Cross Reactivity

An extensive cross-reactivity among the different individual species of the genus could be expected, as well as to a certain degree among members of the families Chenopodiaceae and Amaranthaceae. (9,10)

Last reviewed: May 2022