Expression of cysteinyl leukotriene receptors in tonsillar T and B lymphocytes of children with obstructive sleep apnea

Antiinflammatory medications administered to children with obstructive sleep apnea (OSA) decrease size of pharyngeal lymphoid tissue and severity of airway obstruction. Aim of this study was to define subpopulations of tonsillar lymphocytes with potential susceptibility to inhibitors of cysteinyl leukotriene receptors. Methods: Tonsillar tissue excised from children with OSA or controls with recurrent tonsillitis (RT) was studied for expression of types 1 and 2 cysteinyl leukotriene receptors (LT1R and LT2R) by immunofluorescence and flow cytometry. Results: Ten children with moderate-to-severe OSA (age 5.8±3.3 years) and 10 subjects with RT (7.5±4.7 years) were studied. In both children with OSA and RT, immunoreactivity for LT1R and LT2R was detected in CD3+ tonsillar T lymphocytes (extrafollicular areas) and in CD19+ B lymphocytes (germinal centers and mantle/marginal zones). In subjects with OSA, LT1R+ fraction of small size CD19+ B lymphocytes (median 26.4%, range 4.7%-77.7%) was similar to the LTR1+ fraction of CD3+ T lymphocytes (5.7%, 0.7%-50.3%) and significantly higher than the LT1R+ fraction of large size CD19+ B lymphocytes (3.3%, 1%-31.9%) (p>0.05 and p<0.05). Similar trend was identified for LTR2 in children with OSA or RT and for LTR1 in participants with RT. Conclusions: Children with OSA or RT and tonsillar hypertrophy express cysteinyl leukotriene receptors in B lymphocytes of the tonsillar germinal centers and mantle/marginal zones and in extrafollicular T lymphocytes. These findings explain the beneficial effects of cysteinyl leukotriene receptor inhibitors on pharyngeal lymphoid tissue hypertrophy and OSA.