Understanding the Journey of Human Prenatal CD4+ PLZF+ T Cells to the Small Intestine

The fetal immune system has a variety of needs that differ from those of the adult immune system. One such difference is fetal T cell composition and how they migrate from the thymus to peripheral lymphoid organs and mucosal tissue such as the small intestine (SI). Previous research shows that the majority of memory T cells in the prenatal SI are CD4+ PLZF+ T cells but the mechanisms involved in the homing of these cells in the small intestine have not yet been determined. In our experiment, I found evidence to support the claim that IL-7 drives the acquisition of the memory phenotype in this subpopulation of naive T cells within 2-3 days. Additionally, we saw successful upregulation of other markers necessary for the successful homing of T cells in the gut such as the adhesion molecule - a4b7 and the chemokine CXCR4 within 2-3 days of IL-7 stimulation. By understanding the migration and accumulation of memory T cells in the SI, we might be able to reconstitute fetal immune systems that are lacking in this population and prevent the harmful effects of a deficient immune system