Aberrant Hematopoiesis and CD8⁺ T-Cell Activation in Thymoma-Associated Pure Red Cell Aplasia

Thymoma-associated pure red cell aplasia (PRCA) is a rare autoimmune disorder characterized by selective erythroid lineage suppression. However, the underlying immune mechanisms remain unclear.

We performed single-cell RNA sequencing (scRNA-seq) on bone marrow cells from thymoma-PRCA patients and healthy controls to analyze hematopoietic cell populations. Additionally, we conducted bulk RNA sequencing of peripheral blood CD8 + T cells, flow cytometry analysis of CD8 + T-cell activation, and cytokine profiling of bone marrow supernatant.

scRNA-seq revealed a significant reduction in erythroid progenitors (BFU-E, CFU-E, erythroblasts) and an increase in granulocyte-monocyte progenitors (GMP) in thymoma-PRCA patients. Differential gene expression analysis showed upregulation of TMSB10, AREG, and SPN, which are involved in immune modulation and T-cell activation. Bulk RNA sequencing of CD8 + T cells indicated enhanced expression of activation markers (TNFRSF9, CTLA4, IRF4, CD38, MTHFD2) and decreased expression of erythroid-related genes (HBA1, HBA2, HBB). Flow cytometry confirmed an increased CD8 + T-cell population in the bone marrow, with elevated levels of perforin, granzyme B, IFN-γ, and TNF-α. Cytokine analysis further demonstrated increased IFN-γ and TNF-α levels in the bone marrow microenvironment.

Thymoma-PRCA is associated with excessive CD8 + T-cell activation and an inflammatory bone marrow environment, leading to impaired erythropoiesis. These findings provide novel insights into the immune dysregulation underlying thymoma-associated PRCA and may help identify potential therapeutic targets.