Natural pollen exposition influences sICAM-1 in nasal secretions in birch pollen-allergic rhinitis

The interaction of granulocytes with endothelial cells is an early step in the inflammatory cascade of allergic reactions in the nose. Intercellular a dhesion molecule-1 (ICAM-1) interacts with the beta(2)-integrins LFA-1 and Mac-1. Recently, a soluble form of this adhesion molecule (sICAM) was found in human serum and local body fluids. The biological function of sICAM-1 i s unknown, however, it may prevent from rhinovirus infection in vitro, but not in vivo. The purpose of this study was to investigate levels of sICAM-1 in nasal secretions (NS) in patients allergic to birch pollen with respect to influences of intraseasonal pollen exposition. Additionally, a possible effect of immunotherapy (IT) should be investigated in a prospective, rand omized, controlled parallel-group study. A total of 37 patients were includ ed. 17 patients in the IT group (10 females, 7 males, mean age 28.6 years, 19 - 48 years) and 10 patients in the control group (5 females, 5 males, me an age 25.2 years, 18 - 37 years) could be evaluated according to the study protocol. All patients were sampled intraseasonal 1994 (S1), extraseasonal , both before (E1) and after (E2) IT, and intraseasonal 1995 (S2). Both gro ups were homogeneous at S1 (p > 0.05). sICAM-1 concentrations were signific antly higher during both seasons (S1, S2), than extraseasonally (E1, E2) (a ll p < 0.01). IT had no influence on sICAM-1 in NS (intergroup comparisons at E2 and S2, all p > 0.05). However, IT was clinically effective in reduci ng nasal symptoms. sICAM-1 increases in NS during natural pollen exposition in allergic rhinitis, The clinical efficacy of IT is based on other mechan isms than reduction of sICAM-1 in NS.