The immunology of psoriasis

Effects of cyclosporine on immunologic mechanisms in psoriasis

A major impetus for further investigation of cellular immunologic mechanisms in psoriasis has been the discovery that cyclosporine, a potent immunosuppressive, is highly effective in the treatment of psoriasis. Cyclosporine has significant inhibitory effects on the ability of T cells to become activated. However, a direct activity of this drug on human keratinocyte signal transduction or growth has been difficult to demonstrate at relevant concentrations. Nevertheless, treatment of psoriasis or of 12-O-tetradecanoyl phorbol-13-acetate-treated murine skin with cyclosporine does reverse many epidermal abnormalities that are common to these two systems. This suggests that the compound exerts an indirect effect on epidermal keratinocytes in vivo, perhaps through immunocyte inhibition. During treatment of psoriasis patients, cyclosporine therapy resulted in selective changes in the numbers and functions of certain antigen-presenting cell subsets (which were distinct from Langerhans cells) and T-cell subsets. These changes were accompanied by indirect evidence of decreased T-cell lymphokine release. Lesional activity of cyclosporine-treated psoriasis patients was closely correlated with the degree of T-cell activation caused by antigen-presenting cells. Cyclosporine inhibition of lymphokine or cytokine release may result in decreased recruitment of non-Langerhans antigen-presenting cells into the epidermis and thus decreased immunoreactivity in the lesion.

Immunomodulating cytokines in atopic dermatitis and psoriasis: production of tumour necrosis factor and lymphotoxin by mononuclear cells in vitro

The immunomodulating cytokines, tumour necrosis factor/cachectin (TNF) and lymphotoxin (LT) are thought to play an essential role as mediators of inflammatory reactions. To evaluate the role of TNF and LT in atopic dermatitis (AD) and psoriasis, we investigated their production by mononuclear cells (MNC) in vitro. The 24-h supernatants of lipopolysaccharide (LPS)- and phytohaemagglutinin (PHA)-stimulated and unstimulated MNC from 26 patients with AD and 20 with psoriasis and from 17 non-atopic healthy controls were tested for the concentrations of TNF and LT using an ELISA technique. In patients with AD, TNF levels were significantly decreased in the supernatant of PHA-stimulated (P less than or equal to 0.005) and LPS-stimulated (P less than or equal to 0.02) MNC in comparison to controls. There was no significant difference in TNF production between psoriatic patients and the control group. Release of LT in the supernatant of PHA-stimulated MNC by patients and controls did not differ significantly. There was no significant spontaneous production of TNF and LT by MNC of patients and controls. These studies indicate that different immunomodulating mechanisms are responsible for triggering the inflammatory response in AD and psoriasis.

Successful treatment of a patient with Reiter's syndrome and acquired immunodeficiency syndrome using etretinate

In a 30-year-old homosexual man with a 3-year history of localized psoriasis, an oligoarthropathy and severe cutaneous lesions of Reiter's syndrome developed 6 months after acquired immunodeficiency syndrome (AIDS) was diagnosed. Reiter's syndrome and psoriasis may be a continuum of similarly expressed cutaneous diseases that develop in genetically predisposed individuals. We discuss the possible involvement of T lymphocytes and Langerhans cells in the cutaneous lesions of AIDS patients with psoriasis and Reiter's syndrome. In these AIDS patients, skin disease tends to be severe and recalcitrant to conventional therapy. Etretinate plus topical fluorinated steroids was an excellent treatment, producing near clearance of skin lesions and significant improvement in the oligoarthropathy.

Elevated levels of interleukin 2 receptor in sera of patients with atopic dermatitis and psoriasis

Elevated levels of serum interleukin 2 receptor (IL2R) represent an early measure of T cell activation. The concentration of IL2R was measured in the sera of patients with atopic dermatitis (n = 58) or psoriasis, without psoriatic arthritis, (n = 26), who had moderate to severe disease activity, and in non-atopic healthy controls (n = 37) by an ELISA technique. Serum IL2R levels were found to be significantly elevated in both disease groups compared with the controls. The increase in serum IL2R may be due to T cell activation in the dermis.