D2.216 - Sensitization to legumes after an occupational allergy produced by guar gum

Guar gum is a polysaccharide extracted from guar beans (Cyamopsis tetragonoloba) that has solidifying and stabilizing properties. It is used in food, such as in candy factories and different industrial applications.

The aim of this study was to analyze the cross-reactivity between guar gum and other legumes in a professional allergy case related to guar gum exposure.

The patient was a 56-year-old man who worked in a candy factory where he was respiratory exposed to guar gum, presenting episodes of dyspnea with wheezing. He was relocated years ago. Recently, he had dysphonia and a sensation of a foreign body after eating legumes.

Sensitivity to legumes was tested by skin prick tests (SPT). Sensitization to guar gum was analyzed by ImmunoCAP. Cross-reactivity was studied by inhibition of the patient’s serum with guar gum previously to be added to ALEX², containing 165 allergenic sources  (117 extracts, guar gum not included, and 178 molecular allergens). Reciprocally, patient’s serum was inhibited with lentil and chickpea before its use in ImmunoCAP.

SPT was positive to chickpea, bean, lentil and soybean.

sIgE to guar gum was >100 kU/L.

The patient was sensitized to all legumes present in ALEX², with sIgE values ​​above 20 kU/L for 7/8S globulin from soybean (Gly m 5), lentil and pea.

Inhibition studies demonstrated very high inhibitions percentages of the legumes with guar gum (77 to 91%). Regarding molecular allergens, the highest inhibition was observed with globulins (88% with Gly m 5). Additionally, LTPs of nightshade plantain, peanut and strawberry were inhibited with guar gum. The highest inhibition percentage was observed with peanut LTP (98.5%).

On the contrary, neither lentil nor chickpea inhibited guar gum recognition. The positive inhibition control with guar gum itself resulted in an inhibition greater than 90%.

The symptoms with legumes were caused by a primary sensitization to guar gum. It is therefore important that workers exposed to this product take appropriate protective measures.

The cross-reactivity between guar gum and legumes was mainly mediated by globulins.