Abstract
Background: Corticosteroid administration produces multiple immunomodulatory effects, including down-regulation of cytokine production by CD4 T lymphocytes. Fluticasone propionate (FP) (Glaxo Smith&Kline, Greenford, UK), a highly lipophilic topical corticosteroid, has been shown to be safe and effective in the treatment of asthma and of both seasonal and perennial rhinitis.Aims: To gain insight into the mechanisms of FP therapeutic effects, we evaluated interleukin (IL)-13 (a type 2 cytokine that seemingly plays a pivotal role in allergic mechanisms) production by mitogen-stimulated peripheral blood mononuclear cells (MNC)
in vitro, treated or not with FP.Methods: MNC from 10 healthy subjects and 10 asthmatic atopic patients with Parietaria allergy were stimulated v/v with phytohaemagglutinin (PHA) (50 γ/ml) or with complete medium alone as a control. Culture supernatants, in vitro treated or not with 10-7 or 10-8 M FP, were collected after 48 or 72 h incubation. IL-13 production was assessed by enzyme-linked immunosorbent assay. In random selected samples, after 4 or 24 h of cell cultures, RNA was extracted and IL-4 and IL-5 reverse transcriptase-polymerase chain reaction (RT-PCR) products analyzed.Results: At 48 h, there were no differences in IL-13 concentration in PHA-stimulated cultures between healthy subjects and asthmatic patients (93.6 ± 18.9 versus 111.0 ± 25.1 pg/ml). At 72 h, similar results were obtained (63.9 ± 3.0 versus 73.3 ± 2.5 pg/ml, respectively). At this time, however, IL-13 concentrations were significantly decreased versus 48 h both in asthmatics
(