Milk allergy in HLA-DRB1*14:19/14:21 paediatric patients: a bioinformatics approach

personАвтори: I. Dimitrov, I. Doytchinova, M. Mladenova, T. Kadiyska

Abstract: Allergens are processed in specialized antigen-presenting cells located at mucosal surfaces by the machinery of human leukocyte antigen (HLA) proteins. The susceptibility and protection against some allergies are associated mainly with the polymorphism in HLA class II. The alleles that bind to allergen peptides could be considered as susceptible to particular allergy and the nonbinding alleles – as protective. In the present study, we report the cases of two Caucasian males, 6 and 14 month-old, diagnosed with allergic reactions to β-lactoglobulin (Bos d 5) and BSA (Bos d 6) and genotyped as HLA-DRB1*14:19/14:21. The presence/absence of association between milk allergens and HLA specificity is analysed using bioinformatics tools. The protein sequences were cleaved in silico by pepsin, trypsin and chymotrypsin and the binding affinities to HLA-DRB1*14:19/14:21 of the peptide fragments survived after the digestion were predicted. Practically, after the digestion, no binders to HLA-DRB1*14:19 and *14:21 remain. Both alleles are close in structure to HLA-DRB1*03:01 which is protective against cow’s milk allergy. The bioinformatics analysis showed that the observed milk allergy in these young patients rather is due to age-connected low concentration and activity of chymotrypsin than to HLA specificity.