SECRETORY PATTERN OF ALVEOLAR MACROPHAGES IN ATOPIC ASTHMATIC PATIENTS

The alveolar macrophages (AM), as cells presenting antigen, play a crucial role in initiating immunological responses; upon activation, these cells can synthesize and release a variety of inflammatory mediators such as PAF, LTB4 TxB2, and other arachidonic acid derivates, which are involved in the pathophysiologic processes underlying asthma and bronchial hyperresponsiveness. Moreover, it is well known that activated macrophages can secrete several different proinflammatory cytokines, which are responsible for complex cell- to-cell communications. The aim of this study has been to evaluate in four normal subjects and in eight atopic patients with mild asthma in intercritical phase and with bronchial hyperresponsiveness, the secretory pattern of unstimulated and LPS-stimulated AM culture, studied by radio e/o enzyme-immunoassay. The results show a significantly increased levels of different chemical mediators by 24 h unstimulated culture medium respectively in asthmatic patients and controls such as LTB4 (x ± sd=8.2211.5 vs 2.93±0.3; p=0.02), TxB2 (x ± sd=1 14.4±43.6 vs 30.7±27.1; p=0.02), PAF (x ± sd= 1342.751113.8 vs 340.6±18.5; p=0.05), furthermore significantly increased amounts of IL-lp (46.76±7.4 vs 2.1±3.4; p=0.05) and IL- 8 (41.72±2.2 vs 0.34±0.3; p=0.002) were detected in BAL from asthmatic patients, in comparison with control subjects. On the contrary, no significant difference in the amounts of IL-la (0.63±0.5 vs 0.29±0.1; p=0.31) and IL-6 (6.15±1.0 vs 1.06 vs 1.6; p=0.22) was found. More detailed information about the macrophage secretory pattern were obtained by the 24th hour analyses of the culture medium of unstimulated BAL macrophages from asthmatic and normal subjects. The asthmatic patients exhibited a significantly greater production of IL-lp and IL-8 than the normal subjects (Wilcoxon test: 7.02±7.0 vs 1.1±1.7; p=0.05 and 159±11.3 vs 5.47±2.0; p=0.005, respectively). Again, no significant difference in the amounts of IL-la and IL-6 detected in the two groups was found (0.90±0.4 vs 0.79±0.4; p=l and 2.37±2.2 vs 1.06±1.8; p=0.47, respectively). These results were also confirmed in "vitro" LPS- stimulated culture macrophages at 12, 24, 48 and 72 h.