Antigen-specific induction of osteopontin contributes to the chronification of allergic contact dermatitis.

Allergic contact dermatitis is a T cell-mediated immune response, which in its relapsing chronic form is of high socioeconomic impact. The phosphoglycoprotein osteopontin (OPN) has chemotactic and Th1 cytokine functions and in various models is essential for robust T cell-mediated immunity. Here we demonstrate that OPN is abundantly expressed by both effector T cells and keratinocytes in allergic contact dermatitis lesions.

Beta(2) integrin deficiency yields unconventional double-negative T cells distinct from mature classical natural killer T cells in mice.

Expressed on leucocytes, beta(2) integrins (CD11/CD18) are specifically involved in leucocyte function. Using a CD18-deficient (CD18(-/-)) mouse model, we here report on their physiological role in lymphocyte differentiation and trafficking. CD18(-/-) mice present with a defect in the distribution of lymphocytes with highly reduced numbers of naïve B and T lymphocytes in inguinal and axillary lymph nodes.

TGF-beta-dependent suppressive function of Tregs requires wild-type levels of CD18 in a mouse model of psoriasis.

Dysfunctional Tregs have been identified in individuals with psoriasis. However, their role in the pathogenesis of the disease remains unclear. Here we explored the effect of diminished CD18 (beta2 integrin) expression on the function of CD4+CD25+CD127(-) Tregs using the Cd18 hypomorphic (Cd18hypo) PL/J mouse model of psoriasis that closely resembles the human disease.