Frequency and characteristics of circulating CD4+ CD28null T cells in patients with psoriasis

Abstract

Background Psoriasis is a chronic inflammatory disease that affects the skin. CD4+ CD28null cells are a subset of T lymphocytes associated with systemic inflammation and increased cardiovascular disease risk, and may be involved in the pathogenesis of psoriasis. Objectives To study the features of circulating CD4+ CD28null cells in patients with psoriasis, adjusted for the influence of known cardiovascular disease risk factors. Methods Forty-two patients with psoriasis and 42 controls entered the study. Peripheral blood mononuclear cells were analysed for the frequency of CD4+ CD28null T lymphocytes and their expression of cytotoxic granules and homing receptors. Immunostaining for cutaneous cytotoxic granules was assessed in skin biopsies from 11 patients. Results There were no differences in the frequency of CD4+ CD28null T cells between groups in all situations analysed. However, there was an increased number of cells expressing cytotoxic granules and a decreased number expressing CXCR3 in ex vivo samples of patients with psoriasis. A negative correlation was observed between the frequency of ex vivo CD4+ CD28null cells and psoriasis severity. After clinical remission in nine patients, ex vivo CD4+ CD28null lymphocytes expressing cytotoxic granules decreased. Perforin-, granzyme B- and granulysin-containing cells were found in skin lesions. Patients with psoriasis also had increased plasma levels of C-reactive protein. Conclusions These data suggest that cytotoxic cells, such as CD4+ CD28null lymphocytes, within an inflammatory environment may play a role in the pathogenesis of psoriasis.