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Keywords:

  • linden allergens;
  • linden pollen allergy;
  • rhinoconjunctivitis;
  • Tilia cordata

Allergy to linden pollen (the most common species is Tilia cordata) has not been previously documented.We present the case of a pollinic patient sensitized to linden pollen.

A 21-year-old woman was diagnosed 10 years ago as having rhinoconjunctivitis and asthma caused by olive and grass pollen. After 6 years of specific immunotherapy, she experienced clinical improvement. However, every June, during the last 4 years, she reported nasal, ocular, palatine, ear, and pharynx pruritus; conjunctival hyperemia; sneezing; and night cough. She related it to the flowering of a linden tree near her house. She was asymptomatic in June when she was away from home.

Her white cell count and differential blood count were normal. The total IgE (Pharmacia CAP) was 334 kUA/l. The skin prick test (SPT) to extract of T. cordata pollen (5% w/v) was positive (11×17 mm). SPT was also positive to Lolium sp., Olea sp., Plantago sp., Artemisia sp., Platanus sp., Chenopodium sp., and Parietaria sp.

The conjunctival provocation test (1) was positive in our patient at 0.5 mg/ml. The nonspecific bronchial reactivity test with methacholine (2) was negative. A specific bronchial provocation test (3) was performed with extract of linden pollen and found to be negative. Specific IgE (Pharmacia CAP System) to T. cordata pollen was positive (27.7 kUA/l) and also to pollens of Lolium perenne (13.8 kUA/l), Artemisia vulgaris (10.8 kUA/l), Plantago ovata (9.6 kUA/l), and Platanus acerifolia (15.5 kUA/l).

By means of RAST inhibition with paper disks sensitized to T. cordata and the patient's serum (4), no inhibition of RAST was detected with Lolium, Olea, and Plantago extracts, but a partial inhibition (∼30–40%) was detected with Artemisia and Platanus pollen extracts. IgE immunodetection of T. cordata extract after SDS–PAGE indicated that the patient's serum had IgE against several bands, mainly at ∼50 kDa and also at ∼23 and ∼10 kDa (Fig. 1). Similar bands were detected in the Platanus extract, but the ∼50 kDa band was much weaker. Inhibition of Tilia-IgE immunodetection with Platanus extract showed the existence of cross-reactivity of the smaller bands, but not of the 50-kDa band (Fig. 1).

image

Figure 1. IgE immunodetection experiment: lane 1) Tilia extract; 2) Platanus extract; 3) negative control; 4) inhibition of Tilia-IgE immunodetection with Platanus extract.

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In conclusion, exposure to linden pollen can induce IgE-mediated rhinoconjunctivitis and cough, as demonstrated by SPT, conjunctival provocation, and IgE in vitro tests. A specific 50-kDa linden allergen has been detected. Linden pollen must be taken into account when the patient's symptoms correlate with linden pollination, as other relevant pollens in the area (olive and grass) could hide it (5).

References

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  2. References
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    Feo F, Martinez A, Palacios R, et al. Rhinoconjunctivitis and asthma caused by vine pollen: a case report. J Allergy Clin Immunol 1999;103:262266.