ELEVATED SERUM INTERFERON-GAMMA IN ATOPIC ASTHMA CORRELATES WITH INCREASED AIRWAYS RESPONSIVENESS AND CIRCADIAN PEAK EXPIRATORY FLOW VARIATION

Interleukin (IL)-4, IL-5 and interferon (IFN)-gamma are thought to pla y an important role in chronic airway inflammation in asthmatic subjec ts, Increased airways responsiveness and nocturnal airway obstruction are important clinical manifestations of asthma, The aim of this study mas to investigate whether IL-4, IL-5 and IFN-gamma values are elevat ed in atopic asthma and correlate with its clinical manifestations. Se rum IL-4, IL-5 and IFN-gamma levels of 17 atopic asthmatics and eight nonatopic health subjects were determined at 16:00 and 04:00 h by a ch emiluminescence enzyme-linked immunosorbent assay (ELISA) method, The clinical manifestation of asthma was determined by assessment of the d egree of airway obstruction, airways responsiveness to methacholine an d severity of nocturnal airway obstruction, defined as the mean circad ian (16:00-04:00 h) peak expiratory flow (PEF) variation. Serum IL-4, IL-5 and IFN-gamma levels were significantly higher in asthmatic subje cts as compared to healthy controls, both at 16:00 and 04:00 h, In ast hmatic subjects serum IFN-gamma at both time points correlated signifi cantly with the provocative concentration of methacholine causing a 20 % fall in forced expiratory volume in one second (PC20,meth) (rho=-0.5 5) and with the mean 16:00-04:00 h PEF variation (rho=0.53). In contra st, no relationship mas found between the levels of IL-4 and IL-5 and the parameters of clinical manifestation of asthma. The results sugges t that the serum interferon-gamma level is a reflection of the severit y of airway inflammation in atopic asthma, More studies are needed to detect the cellular sources and to clarify the exact roles of interfer on-gamma and other pro-inflammatory cytokines in asthma.