Increased IgA Expression in Lung Lymphoid Follicles in Severe Chronic Obstructive Pulmonary Disease.

RATIONALE: Accumulation of B cells and lymphoid follicles (LFs) has been described in chronic obstructive pulmonary disease (COPD) airways, but the functional status of lung B cells remains poorly known. OBJECTIVES: To characterize LFs for expression of IgA, the main mucosal antibody. METHODS: The presence of B cells and LFs, including intrafollicular IgA expression, were determined in the lung from patients with COPD (n = 37) versus control subjects (n = 34) by immunohistochemistry. We also evaluated follicular IgA responses in the lungs from mice infected with Pseudomonas aeruginosa (PAO1) (n = 10 per group) and in smoking mice. MEASUREMENTS AND MAIN RESULTS: Whereas in smokers B-cell numbers slightly increased, robust increases in B-cell and LF numbers (mainly in distal airways) were only observed in severe COPD. Most follicular B cells were IgM+ (70-80%), but IgA+ (and not IgG+) B-cell numbers were increased in LFs from severe COPD compared with control subjects (twofold, 44.7% vs. 25.2%), and this was significant in distal but not proximal airways. Follicular IgA response was also observed in PAO1-infected mouse lungs, but not after smoke exposure. Moreover, follicular IgA expression associated with expression of IL-21, which was very potent to activate immunoglobulin production in vitro. CONCLUSIONS: This study shows that IgA production occurs in peribronchiolar LFs from severe COPD, where IL-21-producing T cells are present, and presumably represents a feature of exacerbated mucosal adaptive immune responses against microbial and/or self-antigens.

Repeated KI Prophylaxis in Case of Prolonged Exposure to Iodine Radioisotopes: Pharmacokinetic Studies in Adult Rats.

PURPOSE: To propose a new and effective dose regimen for stable potassium iodide (KI) repeated prophylaxis in case of prolonged exposure to radioactive iodine. METHODS: The pharmacokinetics of iodine was determined in rats by compartmental analyses after intravenous and oral administrations of the optimal dose of 1 mg/kg KI, which was previously selected in a dose-effect study. The thyroid protection against iodine-125 incorporation was followed during 24 h after a single oral dosing of KI. A repeated KI prophylaxis was modeled using initial estimates of iodine pharmacokinetic parameters. RESULTS: A dose regimen consisting in administrations of 1 mg/kg daily for 8 days was selected and studied. Plasma iodine concentrations predicted by simulation were verified by experimental data and varied after the third dose of KI between 174 and 1190 µg/l. The inhibition study of iodine-125 binding in the thyroid as a function of the time showed that the protection effect of KI could be correlated to stable iodine plasma concentrations. Hence, a theoretical decrease in iodine-125 thyroid uptake from 63 to 88% could be achieved in a 24 h-interval between two KI doses. CONCLUSION: Given the satisfactory levels of thyroid protection, this dose regimen could be envisaged in order to extent KI indications for repeated prophylaxis.