High programmed death 1 expression on T cells in aplastic anemia

Area of Science:

• Immunology
• Hematology
• Cell Biology

Background:

• Aplastic anemia (AA) involves aberrant T cell regulation.
• The role of Programmed death 1 (PD-1) in AA pathogenesis requires further investigation.

Purpose of the Study:

• To investigate PD-1 expression on T cells in AA patients.
• To explore the impact of PD-1 on T cell and bone marrow hematopoietic stem cell (BMHSC) apoptosis in AA.
• To elucidate the role of the NF-κB pathway in PD-1-mediated apoptosis.

Main Methods:

• Flow cytometry (FCM) to detect PD-1 and B7-H1 expression, and apoptosis rates.
• Real-time PCR to measure mRNA expression of PD-1, B7-H1, Bax, and Bcl-2.
• In vitro experiments blocking the NF-κB pathway using PDTC in healthy volunteer cells.

Main Results:

• AA patients exhibited elevated PD-1 expression and apoptosis in T cells and BMHSCs compared to healthy controls.
• PD-1 expression on T cells correlated with lymphocyte and hemoglobin levels.
• High PD-1 expression was observed on CD4+CD25+FOXP3+ T cells, with a negative correlation to their percentage.
• B7-H1, the PD-1 ligand, was also upregulated on various immune cells and BMHSCs in AA patients.
• Blocking the NF-κB pathway with PDTC reduced T cell and BMHSC apoptosis and PD-1 expression in a dose-dependent manner.

Conclusions:

• PD-1 is upregulated on T cells in AA patients, contributing to increased apoptosis of T cells and BMHSCs.
• The NF-κB pathway is implicated in PD-1-induced apoptosis of CD4+CD25+FOXP3+ T cells and BMHSCs in AA.