Some studies are just very tedious to do but necessary. This is especially true for studies of descriptive nature. These studies do not usually have any hypothesis to follow. Their task is simply to generate a lot of data and to try to apply system analysis approach to find any correlations. Sometimes they can yield an important information, but mostly they have values as foundation blocks for other studies.
The following new paper from journal Cell is such a study. It deals with a research topic that interests me so I have decided to write short opinion about it.
In this study, research group led by Donna Farber have analyzed human T cell subset distribution in various human tissues across different age group. They have obtained human tissues from organ donors (total of 56 donors).
They observed that there were significant differences between some of T cell subset in lymphoid and non-lymphoid tissues. For example, the frequency of central memory T cells (TCM), for both CD4 and CD8 T cells, were not significantly different among tissues. But the frequency of naive and effector memory (TEM) T cells were significantly different between blood and non-lymphoid tissues. In addition, blood and interestingly lung tissue contained significantly more RA+ terminally differentiated CD8 effector memory T cells (TEMRA) compared to non-lymphoid tissue (intestinal tissue).
More importantly, analysis of T cell subset distribution across age group revealed that the frequency of naive CD4 and CD8 T cells in the blood undergo a significant age-related reduction.
I would be interested to know how these differences of the frequency of T cell subsets between various tissues translates into functional differences in an in vitro assays.
Recent push for more translational research implies that in the future lot more studies on cells from human tissues are anticipated. Human blood is, of course, the most widely accessible human tissue. However, focus on human blood-derived immune cells, without proper comparison with other tissue-derived immune cells, may undermine long-term goals. Comprehensive studies like this one in journal Cell play an important role in putting to diverse observations into simple, easily understandable concepts.
In addition, properly constructed human cell experiments would save lots of laboratory animals from unnecessary experimentation and many times from their pointless and unjustified sacrifice for the name of science. I think it is time for NIH to really apply 3Rs to animal protocol approvals.
For more information about this study, please check the link in this post.