IMMUNOGLOBULIN-A LEVELS IN BRONCHIAL SAMPLES DURING MECHANICAL VENTILATION AND ONSET OF NOSOCOMIAL PNEUMONIA IN CRITICALLY ILL PATIENTS

Local immunoglobulins play a key role in host defense against lung inf ection. We investigated the pattern of evolution of bronchial albumin, IgA, and IgG levels in ventilated ICU patients in relation to nosocom ial pneumonia. Immunocompetent, critically ill patients underwent seri al blood and bronchial protein determinations on Day 1 (intubation day ), and on Days 3, 7, 10, and 14. The variations in proteins levels wer e compared with corresponding Day 1 values in the whole population, an d between patients who developed lung infections (Group A) and the rem aining population (Group B). Forty-four patients were included into th e study. In the whole population, when compared with the baseline valu e, bronchial IgA/albumin ratio increased significantly (Day 3, +58%, p = 0.04); Day 14, +171%, p < 0.01), but serum IgA/albumin and serum an d bronchial IgG/albumin ratios did not change significantly. In Group A, the increase in the IgA/albumin ratio was less than in Group B (Day 3, +15% versus +87%, p = 0.04; Day 14, +29% versus +210%, p < 0.01). No significant differences were observed between the two groups for br onchial and plasma albumin and IgC levels and for bronchial polymorpho nuclear elastase levels. Bronchial IgA production was enhanced in vent ilated patients. A reduction in this enhanced bronchial IgA production might account for the development of nosocomial pneumonia.