Inhibition of adenovirus infection by the bronchoalveolar lavage supernatant in vitro.

Background: Gene transfer using the adenovirus has been discouraging, since the level of recombinant gene expression was always low. Non-specific and specific immune responses prevent infection or kill infected cells. Most of the specific immune responses against the adenovirus are well known and can be eluded at least in animal models. The non-specific immune response is not so well investigated. We have previously demonstrated a strong anti-adenoviral effect of bronchoalveolar lavage (BAL) supernatants of different patients independent of their content of specific anti-adenoviral immunoglobulins of the subclasses IgA, IgG, and IgM. In this paper we examine the influence of defensins and immunoglobulins within the epithelial lining fluid of the lung on the infection of adenovirus type 5.

Methods: Pooled BAL supernatants were separated by gelchromatography; IgA and IgG, respectively were removed from the BAL supernatants by anti-IgA- and anti-IgG affinity chromatography.

Results: The anti-adenoviral capacity could be assigned to the high molecular weight portion including the immunoglobulin- and at a much lower degree the albumin-fractions. All fractions from affinity chromatography; the IgA fraction, the resulting BAL depleted from IgA, the IgG fraction, and the resulting BAL depleted from IgG were highly inhibitory on adenoviral infectivity.

Conclusion: The main anti-adenoviral component in BAL is part of a high molecular weight complex, either being a large protein itself, or being a small peptide bound unspecifically to different bigger proteins. Defensins are not important factors of anti-adenoviral infectivity in the epithelial linig fluid of our patients.