Figure 1: The co-inhibitory ligand, PD-L2, but not PD-L1, is dispensable in E2 mediated protection against EAE. Seven to 8 week old WT, PD-L1-/- and PD-L2-/- mice were implanted with E2 pellets one week prior to immunization with mouse (m) MOG35-55 peptide in CFA/ Ptx. Mice were monitored for signs of clinical EAE. A) mean disease scores from 2 independent experiments with 3-4 mice/group/experiment. *significant difference (p ≤ 0.05) as compared to the respective E2-implanted mice (Mann-Whitney U test). B and C) Histopathological evaluation of spinal cords from PDL1-/- (control and E2-implanted) and PD-L2-/- (control and E2-implanted) mice. Spinal cords from each group, collected on day 24 post-immunization, were fixed in PFA and embedded in paraffin. Ten μm transverse sections from different regions of the spinal cord from each of the groups were stained with Hematoxylin & Eosin to enumerate infiltrating leukocytes and with Eriochrome cyanine to visualize extent of demyelination. Magnification 50 times and 200 times (inset). Sections are representative of 2 experiments (n=3-4/group/experiment).