I am doing experiments of adoptive transfer using alveolar macrophages from CD45.2 mice into CD45.1 mice. Alveolar macrophages in host mice (CD45.1) are eliminated upon intratracheal instillation of clodronate. After 4 and 7 days of clodronate treatment, I implanted alveolar macrophages from CD45.2 mice, and I can only see that around 1% of the donor cells survive. I have confirmed the depletion of macrophages in host mice, and it is around 80-90%. Is there any idea or suggestion you have?