Comparison of neonatal and adult T cells’ responses to TCR, CD43 and TLR5 signals (P1427)

Abstract

Abstract Characterisation of neonatal T cell response is largely incomplete, despite infants under 6 months old are highly susceptible to infections. It has been reported that neonatal cells require strong signals for differentiation into the pro-inflammatory Th1 phenotype, which is needed to fight viral and intracellular bacteria infections. We decided to evaluate the response of human neonatal and adult naïve T cells to two accessory molecules that have been reported to induce a Th1 profile. CD43 is a transmembrane Type One mucin-like molecule that has been proposed as one of the first molecules to make contact with APCs, regulating cell adhesion and function. We found that toll like receptor 5 (TLR5), which recognizes the flagellin monomer, is highly expressed in T-lymphocytes. It was reported that human neonatal CD8 T cells respond to flagellin with a strong expression of IFNγ. We compared the response of ex-vivo human neonatal CD4 and CD8 T cells to TCR and either CD43 or TLR5 signals alone or in combination. We evaluated the expression of cytokines of the major differentiation profiles (Th1, Th2, Th17 and Treg) and found that neonatal cells produce lower levels of all cytokines, with the exception of TGFβ, and have a higher requirement for TCR signals as compared to the adult cells.