Identification of a Lipid Transfer Protein (LTP) in Peanut Extract and Cloning of Two LTP Isoallergens

RationaleThe presence of an LTP in peanut has been hypothesized but never confirmed. The aim was to identify LTP in peanut extract and characterize its physicochemical and immunological properties.MethodsIdentification of peanut LTP with cross-reacting rabbit anti-Cor a 8 antiserum, sera from peach and peanut-allergic patients' sera, and N-terminal sequencing.ResultsPeanut LTP was identified in an acidic extract of peanut meal at 8 kDa by immunoblotting and by N-terminal sequencing. The IgE reactivity of two cloned and expressed isoallergens was demonstrated with sera from peach and peanut-allergic patients by immunoblotting. The immunoblot analysis with patients' sera showed IgE-reactivity to natural LTP in 68% (n = 25) of patients allergic to peanut and peach (Pru p 3 positive) and 24% (n = 17) of peach-allergic patients (Pru p 3 positive), which are asymptomatic to peanut. Only a weak LTP reactivity was detectable in 29% (n = 24) of patients with peanut allergy (Pru p 3 negative).ConclusionsFor the first time peanut LTP is described as a novel allergen with immunological and molecular biological methods. The N-terminal sequence data allowed cloning and production of recombinant LTP from peanut. Based on clinical data we suggest that the main sensitization of peanut allergic patients to peanut LTP is caused by cross reactivity to Pru p 3, but peanut LTP as sensitizing allergen cannot be excluded. The clinical relevance of peanut LTP remains an open question until peanut-allergic patients are challenged with the full panel of peanut allergens. RationaleThe presence of an LTP in peanut has been hypothesized but never confirmed. The aim was to identify LTP in peanut extract and characterize its physicochemical and immunological properties. The presence of an LTP in peanut has been hypothesized but never confirmed. The aim was to identify LTP in peanut extract and characterize its physicochemical and immunological properties. MethodsIdentification of peanut LTP with cross-reacting rabbit anti-Cor a 8 antiserum, sera from peach and peanut-allergic patients' sera, and N-terminal sequencing. Identification of peanut LTP with cross-reacting rabbit anti-Cor a 8 antiserum, sera from peach and peanut-allergic patients' sera, and N-terminal sequencing. ResultsPeanut LTP was identified in an acidic extract of peanut meal at 8 kDa by immunoblotting and by N-terminal sequencing. The IgE reactivity of two cloned and expressed isoallergens was demonstrated with sera from peach and peanut-allergic patients by immunoblotting. The immunoblot analysis with patients' sera showed IgE-reactivity to natural LTP in 68% (n = 25) of patients allergic to peanut and peach (Pru p 3 positive) and 24% (n = 17) of peach-allergic patients (Pru p 3 positive), which are asymptomatic to peanut. Only a weak LTP reactivity was detectable in 29% (n = 24) of patients with peanut allergy (Pru p 3 negative). Peanut LTP was identified in an acidic extract of peanut meal at 8 kDa by immunoblotting and by N-terminal sequencing. The IgE reactivity of two cloned and expressed isoallergens was demonstrated with sera from peach and peanut-allergic patients by immunoblotting. The immunoblot analysis with patients' sera showed IgE-reactivity to natural LTP in 68% (n = 25) of patients allergic to peanut and peach (Pru p 3 positive) and 24% (n = 17) of peach-allergic patients (Pru p 3 positive), which are asymptomatic to peanut. Only a weak LTP reactivity was detectable in 29% (n = 24) of patients with peanut allergy (Pru p 3 negative). ConclusionsFor the first time peanut LTP is described as a novel allergen with immunological and molecular biological methods. The N-terminal sequence data allowed cloning and production of recombinant LTP from peanut. Based on clinical data we suggest that the main sensitization of peanut allergic patients to peanut LTP is caused by cross reactivity to Pru p 3, but peanut LTP as sensitizing allergen cannot be excluded. The clinical relevance of peanut LTP remains an open question until peanut-allergic patients are challenged with the full panel of peanut allergens. For the first time peanut LTP is described as a novel allergen with immunological and molecular biological methods. The N-terminal sequence data allowed cloning and production of recombinant LTP from peanut. Based on clinical data we suggest that the main sensitization of peanut allergic patients to peanut LTP is caused by cross reactivity to Pru p 3, but peanut LTP as sensitizing allergen cannot be excluded. The clinical relevance of peanut LTP remains an open question until peanut-allergic patients are challenged with the full panel of peanut allergens.