Lymphocytes sensitivity to Fas stimulation in healthy and asthmatic children

Abstract

The T cell hypothesis of asthma is based on the concept that the disease is driven and maintained by the persistence of a specialized subset of chronically activated T memory cells sensitized against an array of allergenic, occupational or viral antigens. Overreaction of CD4+ T cells in the peripheral blood and airway tissues is an invariant feature of asthma; therefore a potent mechanism for augmenting the number of activated T cells in this disease would be the resistance to the normally programmed pathway for cell death. The aim of the study was to evaluate the presence of apoptotic markers on peripheral blood lymphocytes from healthy and asthmatic children before and after stimulation with antiCD95 antibodies. The blood was collected from 21 children with atopic asthma suffering from allergic rhinitis because of house dust mite and/or grass pollen allergens and 8 healthy children matched for their age and sex. Blood was mixed with purified mono-clonal antibody antiCD95 (Beckman Coulter), incubated for 24 hours and than stained with Annexin V andPI (Becton Dick-inson). Prepared suspensions were analyzed with Cytomics FC 500 (Beckman Coulter) flow cytometer. Annexin V(+)/PI(-) cells were characterized as early apoptotic, Annexin V(+)/PI(+) as late apoptotic and Annexin V(-)/PI(+) as dead. In unstim-ulated sample from asthmatic children 21.09±11.20% cells were characterized as Annexin V positive/PI negative. After stimulation with antiCD95 Annexin V positive/PI negative cells constituted 18.72±9.42% of cells, p=0.1. In unstimulated sample from healthy children 11.69±6.70% cells were characterized as Annexin V positive/PI negative. In the sample stim-ulated with antiCD95 16.54±2.98% of cells were Annexin V positive/PI negative, p=0.02. There were no differences between results of late apoptotic and necrotic lymphocytes from healthy and asthmatic children. Performed research indi-cates that lymphocytes from asthmatic children are resistant to Fas mediated apoptosis. © Polish Histochemical et Cytochemical Society.