Wheat protein antigens likely play a role in a subtype of psoriasis. - GreenMedInfo Summary

Background/objectives:  Psoriasis patients with raised IgG and/or IgA anti-gliadin antibodies showed clinical improvement in a trial with a gluten-free diet. The selection of patients for the diet treatment was based on the presence of specific antibodies, e.g. the result of humoral immunity. Since psoriasis is now considered to be a T-cell mediated disease we decided to in vitro challenge peripheral blood mononuclear cells (PBMCs) from randomly selected psoriasis patients with well defined wheat proteins/peptides to explore the possibility of identifying a specific antigen in a subgroup of psoriasis patients. Methods:  PBMCs from 37 psoriasis patients (20 females and 17 males; mean age 49 years) and 37 healthy controls (12 females and 25 males; mean age 57 years) were included. All patients did not participate in all experiments. The PBMCs were exposed in vitro with the following wheat proteins/peptidesin various concentrations: total albumins, 0.28 α-amylase inhibitor and synthetic peptides p32-43, p57-68 and p62-75 based on coeliac-active sequences of α-gliadin. The proliferative response was measured as counts per minute after the cells had been pulsed with methyl-(3) H-thymidine. Results: Albumin, α-amylase inhibitor, p32-43 and p 57-68 elicited a significant response in both patients and controls but showed no differences between the groups. The response induced by the α-amylase inhibitor was higher than that induced by the albumin fraction and the p32-43 and p57-68 peptides. Ata concentration of 25μg/ml, 5 out of 36 psoriasis patients responded positively to the p62-75 peptide and none of the 32 controls, using a stimulation index of 2.4 as the cut off level (p<0.05). Those five patients did not show clinical features that differed from the remaining patients. Among the responding psoriasis patients the relative number of CD4(+) cells increased after in vitro challenge with the albumins, 0.28α-amylase inhibitor, p32-43 and p 57-68 peptides. Finally, the three latter antigens could also induce in vitro the expression of the homing antigen CLA (cutaneous lymphocyte antigen) in a few patients and controls. Conclusion:  The data show that the wheat protein antigens, especially p62-75 peptide, might be of interest in a subgroup of psoriasis patients.