T-Cell Changes in Peripheral Blood of Asthmatics During Bronchoconstriction Caused by Histamine Bronchoprovocation

To study the role of T lymphocyte subtypes in acute bronchoconst' rictive responses caused by nonspecific stimuli, we performed bronchial histamine challenge tests in 24 stable asthmatic patients and in 10 nonatopic-nonasthmatic controls. None of the asthmatic patients had had an attack or suffered from an upper respiratory tract infection within the 8 weeks before the challenge test, nor had been receiving corticosteroids. Short acting P2 agonists were stop­ped 6 hours and long acting P2 agonists 12 hours before the challen­ge test. T lymphocyte subgroups, T lymphocyte activation markers and natural killer cells were determined in the peripheral blood be­fore and after the histamine challenge test by two color flow cyto­metry. The results showed that while there were no changes in the percentages and absolute numbers of CD3+CD4+, CD16+CD56+, CD5+CD25+ and CD5+HLA-DR+ cells after the challenge test, CD3+CD8+ cells were higher both as percentages [23.9% (16.7- 36.7) versus 24.5% (16.7-40.5), p<0.05] and as absolute numbers [574 (65-1204)/mm3 versus 686 (163-1192)/mm’, p<0.05] after the challenge test in the asthmatics. Control subjects showed no diffe­rences after nonspecific bronchoprovocation. In view of these findings it can be stated that CD8+ T lymphocytes may have a role in the acute bronchoconstrictive response to nons­pecific stimulus in asthmatic patients.