¿Qué convierte a una proteína en un alérgeno?

Despite allergy being a very common disease that affects 25% of the world population, its origin is still uncertain. Nowadays, there is no definite hypothesis that answers the question: “What makes a protein turn into an allergen?” The objective of this study has been to study factors (biochemical and biophysical) that are believed to be relevant in the allergenic determination of a protein. For this aim, an exhaustive research of the most recent bibliography has been developed. The correlation among protein size, digestion resistance and allergic capacity has been already demonstrated in several studies. Also, protein structure and post-translational modifications, such as phosphorylation or glycosylation, are meant to be related to allergic response. However, not every protein displaying this sort of characteristics trigger an allergic process. Furthermore, a specific protein family has been deeply studied due to its allergic properties, the LTP family. LTPs are proteins that carry lipids as ligands and some members of this particular family are directly involved in allergy, above all food allergy, mainly. On the other hand, allergic mechanisms from Der p 1, Alt a 1 and Pru p 3 have been meticulously analyzed in order to discover a pattern of sensitization in allergy pathways. Despite not reaching a conclusion, the hypothesis that two hits are necessary to spark an allergy response was established. Firstly, the immune system has to be reached by the allergen in a first stage, and secondly, the organism, after a new contact with it, develops the response. Nevertheless, if these were the only conditions for an allergic response, every human being should suffer an allergic reaction to the allergen, but this does not happen. That is the reason why, as many other studies defend, environmental factors must be related to this kind of processes. In addition, the rise of pollution, smoking and a more sedentary lifestyle, make easier the development of this type of diseases. To come to an end, it is possible to affirm that allergic capacity of the antigen is not sufficient condition, but it is also necessary a physiological predisposition determined by one or more environmental factors to trigger an allergic response. The addition of both conditions may trigger the allergic response