Plasma checkpoint protein levels and galectin-9 in juvenile systemic lupus erythematosus

SLE is a disease of the adaptive immune system where T lymphocyte dysfunction has an important role as well. We assessed the plasma levels of checkpoint receptors expressed on T cells, along with Galectin-9 to reflect type-1 IFN activity and IL-2R alpha in childhood SLE patients. Forty-nine children with SLE and15 healthy controls were included. SLEDAI scores were evaluated at the time of sampling. CD25 (IL-2R alpha), 4-1BB, B7.2 (CD86), TGF-beta 1, CTLA-4, PD-L1, PD-1, Tim-3, LAG- 3, Galectin-9 levels were studied by cytometric bead-based multiplex assay panel. Galectin-9 and PD-L1 were significantly higher in SLE patients. Other checkpoint proteins and IL-2R alpha were also higher but did not reach statistical significance. There were significant correlations between SLEDAI and IL-2R alpha, Galectin-9 and PDL1. There were three clinical clusters: Cluster 1 included patients with no major organ involvement, cluster 2 had predominantly haematological involvement(n=16) and cluster 3 (n=11) had predominantly renal involvement. Checkpoint proteins were not different among these three clusters. Our data supports that Galectin 9 and IL-2R alpha are good markers for disease activity in childhood SLE. We need larger series to evaluate differences between disease clusters in SLE. We failed to show a significant correlation with checkpoint proteins and SLEDAI except for PDL1.