PDCD1 and Stroke: However, in an experimental model of stroke, Offner et al. suggested that as the proportion of circulating PD-L1- and PD-L2-expressing CD19+ B cells increased in the periphery and CNS, increased levels of PD-1 limited the infarct volume through inhibiting the function of T cells and microglia; the findings implicate PD-1 signalling as a key factor in limiting CNS inflammation in murine experimental stroke models [31].