In vitro culture of skin-homing T lymphocytes from inflammatory skin diseases.

We, in this study, describe how T lymphocytes in a skin biopsy can proliferate in vitro for up to 3 months by using T-cell growth factors - interleukin-2 (IL-2) and IL-4 yielding approximately 100-160 million T lymphocytes within 1 month. We established cell lines from three tuberculin skin tests, four positive patch tests, 15 of 16 biopsies from atopic dermatitis (AD), 15 of 19 biopsies from mycosis fungoides (MF), 12 of 24 biopsies from psoriasis vulgaris, which was significantly less than AD (P < 0.05), and with a reduced cumulative number of lymphocytes (P < 0.05). Omitting IL-2 and IL-4 led to immediate halt of proliferation. Blood mononuclear cells from patients and biopsies from healthy persons never gave cell lines. All cells were T lymphocytes expressing CD45RO+, HLA-DR+ and CD150. The CD7 expression was significantly increased in cell lines from AD (P < 0.05). T-cell receptor beta-chain studies by using reverse transcription-polymerase chain reaction showed that all T lymphocytes had access to the skin compartment. Single-stranded conformational analysis showed clonally expanded T cells numbering between 40 and 60 clones. After approximately 2 months of growth, the mean CD4+ : CD8+ ratio was for AD 1.20, MF 0.65 and psoriasis 0.85. Patients with AD treated with cyclosporin-A had almost no growth of CD8+ cells in vitro. Our findings indicate a changed homeostasis among skin-homing lymphocytes for in vitro culture. Our culture system of skin-homing T lymphocytes leads to a prominent cellular expansion allowing for a range of studies of in vivo activated skin T lymphocytes.