A quantitative assay for measuring clearance of adenovirus vectors by Kupffer cells

Kupffer cells are a major barrier to systemic adenovirus (Ad) gene therapy because they rapidly and efficiently clear virions from the circulation. The lack of a straightforward quantitative technique for selectively measuring uptake of Ad by Kupffer cells has made it difficult to study the mechanisms by which they recognize Ad. A new method was developed that relies on immunofluorescent detection of Ad within Kupffer cells in mouse liver sections, followed by confocal microscopy and computerized image analysis. The method is sensitive, quantitative and reproducible, with a linear range spanning two orders of magnitude. As an example of the utility of this method, it was found that pre-injecting mice with polyinosinic acid reduces accumulation of Ad in Kupffer cells by approximately 90%.