Mannose-binding lectin (MBL) therapy in an MBL-deficient patient with severe cystic fibrosis lung disease.

Deficiency of mannose-binding lectin has been shown to be a risk factor for cystic fibrosis (CF) patients. We, therefore, decided to treat a patient with CF, mannose-binding lectin deficiency, severe bronchopulmonary Pseudomonas aeruginosa infection, and rapid deterioration of lung function with purified mannose-binding lectin in an attempt to ameliorate the course of the lung disease. The mannose-binding lectin used originated from pooled human donor plasma and was given as an intravenous infusion twice a week for a period of 3 months. The patients's clinical condition was stabilized during the treatment period, but was not improved. No adverse events were observed. However, the lung function assessed as percent forced expiratory volume in 1 sec (FEV1%) and percent forced vital capacirt (FVC%) correlated significantly with the mannose-binding serum lectin levels (rho=+0.68, P=0.008, and rho=+0.73, P=0.004). Additionally, an inverse correlation with the acute phase-reactant C-reactive protein and the proinflammatory cytokine IL-6 was observed (rho=-0.49, P=0.007 and rho=-0.41, P=0.04, respectively). The results emphasize the importance of mannose-binding lectin as a secondary disease modifier in CF. Moreover, purified mannose-binding lectin can safely be administered to chronically ill patients, and may be a potential treatment in CF and other diseases in which mannose-binding lectin deficiency plays a pathophysiological role.