A 31 kDa kidney bean protein and allergy reactions
What it found
A protein from kidney bean, identified as phytohemagglutinin, triggered allergy-related reactions in blood and skin tests from people allergic to kidney bean.
It also reacted with proteins from peanut and black gram in lab tests.
What they found
Studies in people
IgE binding in patients
The purified 31 kDa protein bound IgE in 22 out of 25 patients' sera, which is 88%, in ELISA and immunoblotting. This suggests it is a major allergen for these people.
Skin prick test results
When 14 kidney bean sensitive patients were skin prick tested with the purified protein, 11 of them, or 78%, had a positive skin reaction. Healthy subjects did not react.
Histamine release from basophils
Basophils from 15 patients released histamine after challenge with the purified protein, in the range of 17 to 48%. Basophils from healthy controls released less than 5% histamine.
Animal and lab studies
Cross-reactivity with other legumes
In lab tests, the purified protein cross-reacted with peanut and black gram. It took 185 ng of peanut protein and 228 ng of black gram protein to achieve 50% inhibition of IgE binding, compared with 56 ng for kidney bean itself.
Stability to heat and digestion
The purified protein remained stable after boiling for up to 60 minutes and was not digested by pepsin in simulated gastric fluid for 1 hour. It still bound IgE after boiling.
Protein identity and nature
Mass spectrometry identified the protein as phytohemagglutinin. It is a glycoprotein and showed hemagglutination activity with human red blood cells.
What the authors conclude
“A 31 kDa major allergen of kidney bean was purified and identified as phytohemagglutinin with cross-reactivity to peanut and black gram.”
Also in their conclusions
- They conclude that a 31 kDa kidney bean protein was purified and identified as phytohemagglutinin with cross-reactivity to peanut and black gram.
- They say it may be useful for component resolved diagnosis and therapy of kidney bean allergy.
- They advise that further in vivo studies are needed to confirm its contribution to various symptoms of food allergy.
How it was done
The authors wanted to isolate and characterise a major allergen from kidney bean, because no allergen had been purified from it before, and purified allergens are needed for better allergy diagnosis and treatment.
They purified a protein from kidney bean using column chromatography and tested it with blood and skin from people with a history of kidney bean allergy. They used sera from 25 patients, skin prick tests on 14 of them, and basophils from 15 patients, plus 5 healthy controls.
What it can’t tell you
- This study used blood and skin tests from people, but it cannot show whether the protein causes symptoms when kidney bean is eaten.
- The cross-reactivity with peanut and black gram was measured in lab tests, so it cannot show what happens in people who eat those foods.
- The study did not follow people over time, so it cannot show whether avoiding the protein prevents allergic reactions.
Who paid
- Conflicts
- Competing Interests: The authors have declared that no competing interests exist.
- Authors work at
- CSIR-Institute of Genomics and Integrative Biology, India
The paper
- Title
- Purification and immunobiochemical characterization of a 31 kDa cross-reactive allergen from Phaseolus vulgaris (kidney bean)
- Type
- Study
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Kasera R, Singh AB, Lavasa S, Nagendra K, Arora N (2013). Purification and immunobiochemical characterization of a 31 kDa cross-reactive allergen from Phaseolus vulgaris (kidney bean). PloS one. doi:10.1371/journal.pone.0063063Free full textPubMed 23671655DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error