Characterization Of T-Cell Ontogeny And Other Cell Populations In Pediatric Human Thymus

Immune related diseases, including autoimmune disorders, allergies, graft rejection, tumour growth are still one of the main concerns of current medicine. The complexity of the immune system demands a continuous review of the knowledge employing available technologies. T lymphocytes play a central role in the coordination, regulation and execution of immune responses.
Maturation of T lymphocytes from the thymus towards the periphery elicit several questions regarding the relations between different immune cell populations, which are highly influenced by the processes taking place at the thymus. Such processes, related to differences into immature and mature cell populations of thymocytes, showing different patterns of expression of CD4 and CD8, along with other factors, could reveal useful information still unknown with respect to the spatial distribution and interactions of such cells. In addition, regulatory T cells (Treg) is a subtype of T cell specialised in the regulation of immune responses, and its ontogeny in the thymus also represent an interesting unexplored concept. Here we show extensive and detailed analysis based on characterization and identification of the distribution of different cell populations of thymocytes at the thymus, derived from flow cytometry and 2D images acquired by confocal microscopy.
The distribution of the four major thymic cell populations found is identified, ensuring results reported by previous publications, along with spatial identification of thymocytes, especially focusing on the interactions related to regulatory T cells. Our results demonstrate further reassurance of the presence of different patterns of FOXP3 expression, the marker that characterises Tregs, as well as the inability of CD45RA and CD45RO markers for providing reliable information at the thymus.
Therefore, analysis on the results obtained from a comparison between flow cytometry and confocal microscopy have high reliability and consistency with previous results reported, reinforcing the importance of identification, selection and maturation processes related to Treg cell population for further research focused on autoimmunity and maintenance of self-tolerance.