52: Plasmodium berghei ANKA sporozoite infection induces the formation of liver-associated CD8 T cells that resemble tissue resident memory cells

T cell memory allows for the rapid generation of effective immune responses to previously encountered pathogens. Although most memory T cells recirculate through the body, a recently discovered subset, the tissue resident memory T cells (T RM ), remains in the affected tissue after infection is cleared. By staying in the area most likely targeted by the pathogen in subsequent reinfections, T RM have the potential to elicit faster, more focused, responses than recirculating memory T cell subsets. We have found that following vaccination with irradiated Plasmodium berghei ANKA sporozoites, a population of memory T cells forms in the liver that closely resembles T RM described in other tissues such as the skin and brain. These liver-associated memory T cells (T LAM ) are yet to be shown to be permanently resident in the liver and are characterised by the expression of high levels of CXCR6 and CD69, but low levels of KLRG1. T LAM are long lived and can be found in significant numbers more than 100 days after infection. Strategies to boost numbers of T LAM might be a more effective way to control liver-stage malaria than traditional vaccination strategies focused on generating circulating memory T cells.