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|Biological Function||Actin-binding proteins|
|Latin Name||Prunus persica|
|Categories||Fruits, Food Of Plant Origin|
|Molecular Weight||14 kDa|
The peach allergen, Pru p 4, is a profilin, which can act as an actin-binding protein. Peach profilin is one of the important pan-allergens. Pru p 4 in peach is reported to share similar amino-acid sequence with profilins from other members of the Rosaceae family, such as apple and cherry. It can also cross-react with profilin in pollens from unrelated families such as Artemisia vulgaris, Betula alba, Corylus avellanus, P amygdalus. Pollen food allergy syndrome (PFAS) is found to occur due to cross-reactivity between Pru p 4 and profilins present in trees, grass, and other weeds. Typically, Pru p 4 is found to be associated with mild symptoms of oral allergy syndrome (OAS). Pru p 4 was identified as a marker allergen for predicting non-systemic symptoms in peach allergy.
Pru p 4 in peach is a profilin which is an important pan-allergen found in various pollen and vegetable sources (1). A prospective cross-sectional study in Spain among 57 children identified Pru p 4 in peach as a minor allergen as the sensitization to Pru p 4 was quite low (10% of 39) (2). A cross-sectional study on 148 peach allergic patients from Italy showed that 40.8% (31/76) patients with Pru p 4 sensitivity showed mild OAS (3). Another study in Japan involving 27 peach allergic patients showed that Pru p 4 sensitization resulted in oral allergy symptoms (4). Furthermore, a retrospective study in Japan using 90 patients with peach allergy showed that sIgE to Pru p 4 was negatively associated with the occurrence of systemic symptoms due to peach (5).
The presence of Pru p 4 has been reported in both pulp and peel of peach fruit (2).
A cross-sectional observational study in 148 peach-allergic individuals identified that Pru p 4 sensitivity is usually associated with mild symptoms of oral allergy syndrome (OAS) pertaining to the oral mucosa (3). In this study, around 41% (n=76) of patients had mild OAS symptoms while 18% (n=72) of patients suffered with severe OAS symptoms due to Pru p 4 sensitivity (3).
A study by Inomata et al. (2017) in Japan identified PFAS in most of the patients (80% of 100) either due to Pru p 1 and/or Pru p 4 sensitivity (6).
PFAS can arise due to cross-reactivity between Pru p 4 in peach and profilins in tree, grass, and weed pollen (4). Although, alder pollen might be the primary contributor for oral symptoms in peach allergic patients with Pru p 1 and/or Pru p 4 sensitization (4).
In a prospective, cross-sectional study by Boyano-Martinez et al. (2013) a patient with positive Pru p 4 antibodies had reported similar symptoms of OAS with melon, watermelon, and pear (2). This could be due to the wide distribution of profilins in various pollens and fruits (7).
Pru p 4, a profilin, is a eukaryotic protein (8) that possess a molecular weight of 14 kDa (9). Profilins are generally actin-binding proteins which can help in several cell processes such as cell movement, signaling, etc. (10). Pru p 4 is also a typical pan-allergen (like Pru p 1 and Pru p 3) and hence can often cross-react (11). Pru p 4 is found to be labile at intense temperature and pH conditions and can get destroyed in the gastrointestinal tract (12).
Pru p 4 has two variants that are mentioned in the below table (9). A study reported that all tissues showed equal expression of Pru p 4 variants. These allergens can induce allergenicity in peeled peach fruit (12).
Isoallergens of Pru p 4
|Isoallergen and variants||Features|
|Pru p 4.0101||
|Pru p 4.0201||
The Pru p 4 variants displayed about 80% similarity in their amino acid sequences. Pru p 4.0101 showed more than 90% sequence similarity to profilins from other Rosaceae fruits, such as cherry and apple (7). Pru p 4.0201 showed more than 70% similarity to amino acid sequence from botanically unrelated foods such as soybean and carrot and pollens such as birch and sunflower (7). A comparative study by Cuesta-Herranz et al. (1999) identified that cross-reactivity between peach profilins and botanically unrelated pollens (Artemisia vulgaris, Betula alba, Corylus avellanus, P amygdalus) exists (1). A recent study also showed that cross reactivity between a muskmelon profilin (Cuc m 2.0101) and Pru p 4.0101 exists due to similar amino acid sequence and identity (10). Additionally, a melon profiling study identified that profilin’s IgE cross reactivity depends more on the conformational structure than the amino acid sequence similarity rate (13).
A prospective study carried in 29 peach allergic patients pointed that individuals with a positive Pru p 4.01 but negative skin prick test (SPT) to Pru p 3 experienced more OAS symptoms and lesser systemic reactions than those with negative Pru p 4.01 and positive Pru p 3 (7). Evidence suggest that co-sensitization of Pru p 3, Pru p 1, and/or Pru p 4 among peach allergic patients may provide a shield against severe symptoms due to Pru p 3 (3, 14).
A retrospective study with 90 peach allergic children in Japan concluded that sIgE of Pru p 4 was an accurate predictor (100% specificity and 61% sensitivity) of non-systemic peach allergy (5).
Rodriguez-Perez et al. (2003) identified in their study with 29 patients that all 15 sera with positive Bet v 2 reacted with Pru p 4 isoallergen (Pru p 4.01). Whereas no sera reacted with Pru p 4.01 in 14 patients without IgE antibodies to birch profilin. Thus, implying that sIgE to birch profilin (Bet v 2) can act as a diagnostic marker for detecting sensitivity to Rosaceae fruit profilins (7).
The main exposure route for this allergen is through ingestion (9).
Author: Turacoz Healthcare Solutions
Reviewer: Dr. Christian Fischer
Last reviewed: January 2021