Increased Number of Circulating Myeloid Dendritic Cell 1 in Patients with Severe Aplastic Anemia

A deeper understanding of the immune pathogenesis of severe aplastic anemia (SAA) is required to improve therapeutic effects. Myeloid dendritic cell (mDC) is involved in the initiation of immune disorders in SAA patients. The objective of this study was to characterize the subsets of mDC in patients with SAA.

A total of 136 SAA patients diagnosed in the Hematology Department of Tianjin Medical University General Hospital from December 2020 through November 2024 and 39 healthy controls were enrolled in this study. The percentages of the two main subsets of mDC (mDC1 and mDC2) in SAA patients with different disease status and healthy controls were detected by flow cytometry, and their correlations with the immune status and severity of SAA were analyzed.

The mDC/plasmatoid dendritic cell (pDC) ratio of the untreated SAA group was significantly higher than that of the healthy control group (51.60 ± 122.16 vs. 4.77 ± 5.86, p = 0.015). MDC1 is the primary subset of mDC in all groups. The percentage of mDC1 in the untreated SAA group [(55.39 ± 22.99)%] was significantly higher than that in the partial remission group [(28.22 ± 26.37)%, p = 0.00], complete remission group [(25.55 ± 23.12)%, p = 0.00], and healthy control group [(19.22 ± 22.77), p = 0.00]. The percentage of mDC1 in the non-remission group [(40.25 ± 29.91)%] was significantly higher than that in the healthy control group [(19.22 ± 22.77)%, p = 0.026]. In the untreated SAA group, there was a significant negative correlation between the percentage of mDC1 and the reticulocyte count (r = -0.284, p = 0.048). There was no statistical difference in the percentage of mDC2 among the groups.

The activation of mDC1, rather than mDC2, might be involved in the pathogenesis of SAA. MDC1 intervention may have therapeutic potential in treating SAA.