Peanut cross-reacting allergens in seeds and sprouts of a range of legumes

BACKGROUND

Recently, peanut-allergic patients have reported symptoms upon ingestion of bean sprouts produced from various legumes.

OBJECTIVE

This study was designed to identify immunoreactivity to seeds and sprouts of legumes other than peanut in sera from peanut-allergic patients.

METHODS

Crude protein extracts of seeds and sprouts (comprising cotelydons and hypocotyls/epicotyls) of peanut, soybean, green pea, blue lupine, mung bean, alfalfa, broad bean, and azuki bean were prepared. The reactivity of sera from 10 peanut-allergic patients to these extracts was analysed by indirect histamine release (HR), enzyme-allergosorbent test (EAST), EAST inhibition, and Western blots. Skin prick tests (SPTs) were performed on the patients with fresh legume seeds as well as four commercial legume sprouts, and food challenges with soybean, pea, and lupine were performed on a subgroup of the patients.

RESULTS

All legume seeds and commercial sprouts induced positive SPTs in some of the patients. Indirect HR experiments indicated an extensive co-reactivity between peanut and the legumes, and cross-reactivity was observed for soybean, pea, and lupine seeds as well as lupine hypocotyls in EAST inhibition experiments. Of the 16 protein extracts, soybean, pea, and lupine seed extracts produced visible bands in Western blots.

CONCLUSION

The symptoms reported by peanut-allergic patients after legume sprout intake might be caused by cross-reactivity of peanut-specific antibodies. The intake of raw legume sprouts might cause symptoms in peanut-allergic patients.

Quantitative trait loci affecting plant regeneration from protoplasts of Brassica oleracea

Quantitative trait loci (QTLs) controlling the plant-regeneration ability of Brassica oleracea protoplasts were mapped in a population of 128 F(2) plants derived from a cross between the high-responding, rapid-cycling line and a low-responding, broccoli breeding line of B. oleracea. A modified bulked segregant analysis with AFLP markers identified two QTLs for plant regeneration. In a multiple regression analysis, the two QTLs explained 83% of the total genetic variation for regeneration recorded 15 weeks after initial transfer of microcalli to regeneration medium. Both QTLs showed additive effects, and the alleles contributing to the high regeneration frequencies were derived from the high-responding, rapid-cycling line. Using microsatellites with known location, the two QTLs were mapped to linkage groups O2 and O9 on the map published by Sebastian et al. [(2000) Theor Appl Genet 100:75-81] or to chromosomes C8 and C7 on the map published by Saal et al. [(2001) Theor Appl Genet 102:695-699]. QTLs for the early flowering trait of the rapid-cycling parent have previously been mapped to the same two linkage groups. Association between flowering time and regeneration ability was, however, not found in the present material, indicating that plant-regeneration ability can be transferred between cultivars independently of the early flowering trait. The detection of two major QTLs for plant regeneration in B. oleracea may provide the initial step towards the identification of markers suitable for marker-assisted selection of regeneration ability.

Allergenic components of a novel food, Micronesian nut Nangai (Canarium indicum), shows IgE cross-reactivity in pollen allergic patients

BACKGROUND

New foods may present a risk for food hypersensitive patients. Several examples exist of allergic reactions caused by cross-reactive plant-derived foods, and new foods should be scrutinised before introducing them to the market. We have evaluated the clinical and serological relevance of cross-reactivity between Nangai and pollen allergens.

METHODS

Cross-reactivity was examined with Maxisorp RAST (radioallergosorbent test), RAST inhibition and Western blot, using sera from patients allergic to grass, birch and mugwort pollen. None of the patients reported having seen or eaten Nangai previously. To determine the biological and clinical relevance of the cross-reactivity, histamine release (HR) test, skin prick test (SPT) and food challenge were used.

RESULTS

There was prevalence for reactivity against Nangai in the group of pollen allergic patients. This cross-reactivity seems to be related--at least in part--to carbohydrate epitopes. Three out of 12 patients tested with Nangai were positive upon open challenge, but using double blind placebo controlled food challenge (DBPCFC) this could not be confirmed in two patients. The biological effects of Nangai on allergic patients were confirmed using HR and SPT.

CONCLUSION

The Nangai specific IgE found among pollen allergic patients addresses the need for control of new or changed foods before introduction to the market.