Increased CD8+ T cells in patients with Henoch–Schonlein purpura nephritis exhibit suppressive immune activity

About 40% to 50% of children with Henoch-Schonlein purpura often suffer from nephritis, which can cause irreversible renal damage. Significantly increased peripheral T lymphocytes and reduced B lymphocytes have been widely reported as hallmarks of Henoch-Schonlein purpura nephritis (HSPN) differing from Henoch-Schonlein purpura without nephritis (HSP). While the role of peripheral immune cells, especially CD8+ T cells, in the development of nephritis of Henoch-Schonlein purpura is not clear.To explore the changes of peripheral CD8+ T cells and the association of CD8+ T cell markers with indicators of renal function in HSP and HSPN patients.A total of 27 HSP and 16 HSPN patients were included in this study. The serum urea, serum creatinine, 24-hour urinary protein and peripheral white blood cell counts were collected from hospital registry systems. The T cell surface markers (CD28, CD107a and CD69) and cytokine (TNFα and IFNγ) secretion capacity were measured by flow cytometry.Compared with HSP patients, The number of CD8+ T cells in HSPN patients increased significantly (p=0.0003) and demonstrated with decreased CD69 expression (p<0.0001) and decreased cytokine secretion. The expression level of CD69 in CD3+, CD4+ and CD8+ T cells all significantly correlated negatively with serum creatinine and 24-hour urinary protein in HSP and HSPN children.The inhibition of CD8+ T cell activity was significantly related to the decline of renal function in HSP and HSPN patients. It is possible to monitor renal function by detecting the expression of CD69 on CD8+ T cells in HSP and HSPN patients.