Objective: To investigate the relationship between the dendritic cell (DC) subsets and transcriptive factors, T-bet, GATA-3, and immune imbalance in acquired severe aplastic anemia (SAA).
Methods: The DC1 (HLA-DR+Lin-CD11c+) and DC2 (HLA-DR+Lin-CD123+) in peripheral blood mononuclear cells (PBMNC) were measured with flow cytometry (FCM), the expressions of T-bet mRNA and GATA-3 mRNA in PBMNC with semiquantitative RT-PCR and the plasma level of IFN gamma and IL-4 with ELISA in 29 SAA patients and 16 healthy controls.
Results: The percentages of DC1 in PBMNC were (0.44 +/- 0.24)% and (0.73 +/- 0.30)% in untreated and recovered SAA patients respectively, both were higher than that in controls (0.29 +/- 0.10)% (P < 0.05). The percentage of DC2 in the untreated cases was lower than that of recovered ones or controls [(0.18 +/- 0.14)% vs (0.28 +/- 0.20)% and (0.29 +/- 0.13)%] (P < 0.05). DC1/DC2 ratios were 3.45 +/- 2.71 and 2.90 +/- 0.95 in untreated and recovered groups respectively, both were higher than that in controls (1.15 +/- 0.56) (P < 0.05). No statistic difference in DC1/DC2 ratio was found between untreated and recovered patients (P < 0.05). The relative mRNA expression levels of transcriptive factor T-bet were 0.37 +/- 0.07, 0.20 +/- 0.07 and 0.17 +/- 0.05 in the above 3 groups, respectively, untreated group being higher than that of recovered group or healthy controls (P < 0.05). There was no statistic difference of GATA-3 expression among the 3 groups (P > 0.05). T-bet/GATA-3 ratio was 0.72 +/- 0.13 in untreated group, being higher than that of recovered group (0.33 +/- 0.08) or controls (0.35 +/- 0.11). The plasma level of IFN gamma in the untreated group was (50.9 +/- 1.1) ng/L, which was higher than that of recovered group [(49.7 +/- 0.9) ng/L] or controls [(49.7 +/- 0.7) ng/L]. There was significant positive correlations between T-bet and DC1/DC2 ratio (r = 0.445, P < 0.01), as well as between T-bet and IFN gamma (r = 0.402, P < 0.01).
Conclusion: Either DC1/DC2 or T-bet/GATA-3 ratio might become an index to estimate immune imbalance. High-expressed T-bet was related to the progress of SAA. In patients with SAA, DC1/DC2 ratio returns to normal range later than that of routine blood test does, indicating that immunosuppressive therapy should not be withdrawn too earlier.