Increased lymphocyte infiltration in duodenal mucosa from patients with psoriasis and serum IgA antibodies to gliadin

Abstract

In a screening study concerning IgA and IgG antibodies to gliadin (IgA AGA and IgG AGA, respectively) in psoriasis, raised levels of IgA and AGA were found to be more common than in a reference group. To determine whether elevated AGA levels were associated with an increased number of intraepithelial lymphocytes, 33 patients with IgA AGA (n = 28) or IgG AGA (n = 5) values above 90% of the reference values (> 50 units/ml IgA AGA and < 12 units/ml IgG AGA) underwent gastroduodenoscopy and duodenal biopsy in a prospective study. For comparison, six patients with low levels of both IgA AGA and IgG AGA were included. Five biopsy specimens were taken in each patient. Paraffin-embedded specimens were examined with regard to the degree of intraepithelial lymphocyte infiltration, and scored from 0 to 3. Biopsy specimens with a score of 0 had one mononuclear cell or less per four epithelial cells. The specimens were also examined with regard to the presence of intraepithelial CD3+ T lymphocytes and gamma/delta+ T lymphocytes. In the six patients with low IgA AGA and low IgG AGA, the biopsy score was 0. Fourteen of the 33 patients with raised AGA had a score of > or = 1; of these, 12 had raised IgA AGA and two had slightly raised IgG AGA. Two of the patients with raised IgA AGA had partial villous atrophy, but the majority had normal villous architecture. There was a significant correlation both between the biopsy score and the number of intraepithelial CD3+ cells and between the score and the number of intraepithelial gamma/delta+ positive T lymphocytes. The serum IgA AGA levels were significantly correlated with the duodenal biopsy score, the number of intraepithelial gamma/delta+ T lymphocytes, and the number of CD3+ intraepithelial T lymphocytes. Most patients had no, or only mild, gastrointestinal symptoms. Of the 14 patients with biopsy scores > or = 1, seven had severe psoriasis and five moderately severe psoriasis, whereas only two had mild psoriasis. There was no relationship between the duodenal score and haemoglobin, folate, whole blood selenium or serum zinc levels. Some of these patients improve on a gluten-free diet, but it is still too early to draw any definite conclusions concerning the type of relationship between the skin lesions, the increased number of intraepithelial lymphocytes in the duodenal mucosa and gluten hypersensitivity.