Increased apoptosis of peripheral blood mononuclear cells in patients with perennial allergic asthma/rhinitis: relation to serum markers of apoptosis

Abstract

Background: The goal of our study was to examine spontaneous and stimulated apoptosis of peripheral blood MNC from allergic patients, sensitized to Der p I antigen as compared to cells from non-atopic subjects. Furthermore we aimed to investigate which populations of mononuclear cells (lymphocytes, monocytes) undergo the apoptosis and to determine relations between apoptosis and serum levels of sFas/APO-1, ICE/caspase-1 or TNF-α.Methods: The study included 17 patients with perennial, allergic asthma and/or allergic rhinitis [6 male and 11 female; mean age 29,5 years; (range 15-49)].Apoptosis was assessed by fluorescence technique and confirmed by flow-cytometric method and DNA ladder. Serum levels of sFas, ICE/caspase-1 or TNF-α were determined by immunoassays (ELISA).Results: Apoptotic index of unfractionated mononuclear cells (MNC) and lymphocytes (but not monocytes) were significantly higher in allergic patients as compared to non-allergic subjects after 48 and 72 hours of culture (p<0.05). Incubation of cells with ConA (10 μg/ml) resulted in a significant increase in the proportion of apoptotic cells in all populations once the apoptotic index for MNC and lymphocytes (but not monocytes) was again significantly higher in allergic as compared to non-allergic subjects after 24, 48 and 72 hour of culture.In allergic patients, mean serum sFas level, was significantly lower then in non-allergic group (mean value 624.8 pg/ml ± 25.67 versus 802.0 pg/ml ± 31.91;p=0.003) and in both groups sFas level correlated inversely with apoptosis of MNC. The mean ICE/caspase-1 concentration was significantly higher in sera of allergic patients as compared to non-allergic group (mean value 27.71 pg/ml ± 3.79 vs 23.54 pg/ml respectively;p<0.01). ICE/caspase-1 levels in allergic patients correlated with apoptotic index of mononuclear cells (r=0.57;p<0.001).Conclusions: An increased spontaneous and mitogen-induced apoptosis of MNC from peripheral blood of atopic patients as well as different serum levels of sFas and ICE/caspase-1 correlating with apoptosis, suggest different regulation of apoptotic process in peripheral blood mononuclear cells of patients with allergic asthma and/or rhinitis.