Departamento de Biotecnología, Unidad de Bioquímica, E.T.S. Ingenieros Agrónomos, UPM, Madrid, Spain.
Clin Exp Allergy. 2010 Jan;40(1):174-81. doi: 10.1111/j.1365-2222.2009.03401.x.
Plant profilins are described as minor allergens, although with some exceptions in foods such as melon, watermelon or orange. In fact, they could be responsible for many cross-reactions among distantly related species. This is likely to be a consequence of the presence of common epitopes.
To characterize the B epitopes of Cuc m 2, a model of plant food profilin, using phage display techniques and to compare with other profilins, such as those of timothy grass and birch pollen, and human I profilin, to understand the mechanism of cross-reaction among members of this family.
IgE of melon-allergic patients was used to select clones from a phage display 12 mer peptide library. After two rounds of screening, Cuc m 2-specific clones were eluted and the DNA insertion sequenced. The residues of each clone were mapped on the Cuc m 2 surface to define a mimotope, which was also localized on the three-dimensional surfaces of other profilins.
Seventeen melon-allergic patients were selected. Sera from each of them recognized the melon profilin, Cuc m 2, but the majority also recognized Phl p 12 or Bet v 2, timothy grass-, and birch-pollen profilins, respectively. A Cuc m 2 mimotope was defined and mapped onto its surface giving the following sequence: S(2)W(3)A(5)Y(6)D(9)H(10)T(111)P(112)G(113)Q(114)N(116)M(117)R(121)L(122). The homologous residues in Phl p 12 and Bet v 2 had almost identical sequences. By contrast, the homologous sequence in human profilin showed many differences.
The identified mimotope could be involved in cross-reactions among food and pollen profilins. Many of these cross-reactions observed in the clinical realm could be explained by the presence of a common epitope found in food and pollen allergens. A new strategy of immunotherapy based on this IgE region could be used in alternative immunotherapy strategies.
植物亲免素被描述为次要过敏原，但在某些食物中（如甜瓜、西瓜或橙子）存在例外。事实上，它们可能是导致亲缘关系较远的物种之间发生许多交叉反应的原因。这很可能是由于存在共同表位。
使用噬菌体展示技术对植物食品亲免素模型 Cuc m 2 的 B 表位进行表征，并与其他亲免素（如梯牧草和桦树花粉中的亲免素）和人 I 亲免素进行比较，以了解该家族成员之间交叉反应的机制。
使用甜瓜过敏患者的 IgE 从噬菌体展示 12 mer 肽文库中筛选克隆。经过两轮筛选，洗脱 Cuc m 2 特异性克隆并测序 DNA 插入片段。将每个克隆的残基映射到 Cuc m 2 表面上，以定义一个模拟表位，该模拟表位也定位于其他亲免素的三维表面上。
从 17 位甜瓜过敏患者中筛选出 17 位患者。他们的血清均能识别甜瓜亲免素 Cuc m 2，但大多数患者还能识别 Phl p 12 或 Bet v 2、梯牧草和桦树花粉亲免素。定义了一个 Cuc m 2 模拟表位，并将其映射到表面上，得到以下序列：S(2)W(3)A(5)Y(6)D(9)H(10)T(111)P(112)G(113)Q(114)N(116)M(117)R(121)L(122)。Phl p 12 和 Bet v 2 中的同源残基具有几乎相同的序列。相比之下，人亲免素中的同源序列存在许多差异。
鉴定出的模拟表位可能参与了食物和花粉亲免素之间的交叉反应。在临床领域观察到的许多交叉反应可以用食物和花粉过敏原中存在的共同表位来解释。一种基于该 IgE 区域的新免疫治疗策略可用于替代免疫治疗策略。
