Abundant specialized T follicular helper cells in the lamina propria of human infant intestines

Abstract

The worldwide main cause for six million deaths of under-five year old infants in 2015 are infectious diseases. Vaccines could contribute to reduce this number. However, infants present a weaker response upon vaccination than adults, which is most likely associated with their immature and suppressive immune system early in life. T follicular helper (TFH) cells are a pivotal actor in the induction of protective antibodies, due to their ability to activate and promote B cells. In this study, it could be demonstrated, that TFH cells in infant intestinal mucosae are abundant in comparison to TFH cells in adult intestinal mucosa. Compared to adult TFH cells, the infant TFH cells present a diminished expression of the master transcription factor Bcl-6. Nevertheless, the infant TFH cells predominantly showed an effector memory tissue-resident phenotype and therefore appeared to be as mature as the adult TFH cells. Whether the infant TFH cells can sufficiently interact with other cells and properly induce B cells needs to be investigated in further studies.