INTERCELLULAR-ADHESION MOLECULE-1 IS UP-REGULATED ON PERIPHERAL-BLOODT-LYMPHOCYTE SUBSETS IN DUAL ASTHMATIC RESPONDERS

To examine the role of adhesion molecules in T cell recruitment and ac tivation during allergen-induced late asthmatic response (LAR), we eva luated the expression of lymphocyte function-associated antigen-1 alph a (LFA-1 alpha) and intercellular adhesion molecule-1 (ICAM-1) on peri pheral blood T lymphocyte subsets from atopic asthmatic patients and t heir changes following allergen inhalation challenge. 12 atopic asthma tic patients were studied. Six patients showed only a single early res ponse after allergen challenge, and six developed a dual response. At baseline, dual responders (DR) had a significantly higher expression o f ICAM-1 on CD4(+) and CD8(+) T lymphocytes as compared with both sing le early responders (P < 0.005 and P < 0.02, respectively) and control s (P < 0.001, both comparisons). Allergen challenge was followed by a decrease of CD8(+) ICAM-1(+) T lymphocytes in all DR (P < 0.05) and of CD4(+) ICAM-1(+) T lymphocytes in four out of six DR, at the time of the LAR. At the same time, a significant rise in serum levels of the s oluble form of ICAM-1 was observed in DR. These results suggest that p eripheral blood immunoregulatory T lymphocytes are in a higher state o f activation in DR as compared with early responders. The upregulation of ICAM-1 on these cells may be important in enhancing airway inflamm ation in patients with LAR.