Cholinergic staining of bronchus-associated lymphoid tissue

The cholinergic staining of human bronchus-associated lymphoid tissue (BALT) was studied in humans. Morsels of the human lung (containing BALT) were harvested, after having obtained the appropriate approvals, during autopsies in 24 human subjects. The samples were stained by means of the enzymatic technique of acetylcholinesterase (AChE) and/or the monoclonal immunohistochemical method of choline acetyltransferase (ChAT). A morphometrical analysis was performed by means of quantitative analysis of images and statistical analyses of the data. AChE and proteins were also measured by biochemical assay. Our results demonstrate that both AChE and ChAT are localized in the BALT of young and old humans. These enzymes undergo age-related changes. The biochemical values of AChE are as follows: 22.3 +/- 2.5 international units in young subjects and 78.5 +/- 1.9 international units in old ones. The morphometrical values of AChE confirm the biochemical ones. The morphometrical data for ChAT are 31.6 +/- 1.4 conventional units in young subjects and 71.2 +/- 1.5 conventional units in old ones. Further results are needed to draw definite conclusions concerning the location and the distribution of these two enzymatic activities in BALT. In our opinion, the presence of AChE and ChAT in BALT can be both 'non-neuronal', with a role in general metabolism, and/or 'neuronal' with a role in neuroimmunomodulation. Copyright (c) 2005 S. Karger AG, Basel.