Abstract: Objective To evaluate the ability of altered peptide ligands(APLs)to inhibit the activities of psoriatic T cells.Methods Peripheral blood T cells were isolated from 52 patients with psoriasis and 48 healthy human controls.The APLs targeting T cell epitopes of keratin 17 were synthesized.The peripheral blood monocytes were incubated with the wild T cell epitopes,APLs or control peptides(glutathione Stransferase,GST).These monocytes were then used as antigen presenting cells to interact with T lymphocytes from the same individuals.MTT method was used to detect the proliferation of T lymphocytes,and ELISA assay to measure the levels of IFN-γ,IL-2,IL-4 and IL-10 in the culture supernatants of these T lymphocytes.Results Compared with GST and blank control,the APLs,119R and 355L at a concentration of 10 and 100μg/mL significantly down-regulated the proliferation of psoriatic T cells(P<0.05);no obvious inhibition of proliferation of cells from healthy controls was noted.APLs at 10 and 100μg/mL also decreased the secretion of IFN-γand IL-2 in the supernatants ofT cells,and increased the levels of IL-4 and IL-10 in comparison with the wild epitopes(all P<0.05).Conclusion Our findings show that APLs,119R and 355L,are capable of inhibiting the proliferation of psoriatic T cells and facilitating the differentiation to Th2 cells in vitro.

Key words: Psoriasis, Keratin, Epitopes, T-lymphocyte, Altered peptide ligand