Circulating Dendritic Cells of the Patients with Myelodysplastic Syndromes.

Objective To investigate the quantity, subsets of dendritic cells(DC) and costimulatory molecule expression in peripheral blood(PB) of the patients with myelodysplastic syndromes(MDS).

Methods Total DC(Lin1+HLA-DR+), myeloid DC(mDC) (Lin1+HLA-DR+ CD11c+) and plasma DC(Lin1+HLA-DR+CD123+) in fresh whole PB samples of 38 MDS patients and 19 normal controls were assayed with flow cytometer and the monoclonal antibodies. The expression of CD80, CD86 and CD40, the costimulatory molecules on these DC were also assayed in the same way.

Results. Total DC in PB of MDS patients was more than that of normal controls significantly [(41.4±10.9)×10⁶/L vs (12.1±1.4)×10⁶/L](P<0.05). mDC in PB of MDS patients was more than that of normal controls too [(20.8±7.2)×10⁶/L vs (5.5±0.9)×10⁶/L](P<0.05). pDC in PB of MDS patients was not significantly more than that of normal controls [(9.5±2.8)×10⁶/L vs (6.6±0.7)×10⁶/L] (P>0.05). The percentage of total DC in PB mononuclear cells(PBMNC) of MDS patients was higher than that of normal controls[(2.78±0.59)% vs (0.68±0.08)%](P<0.05). The percentage of mDC in PBMNC of MDS cases was also higher than that of normal controls[(1.15±0.33)% vs (0.32±0.05)%](P<0.05). The percentage of pDC in PBMNC of MDS cases was not significantly higher than that of normal controls[(0.64±0.19)% vs (0.37±0.04)%](P>0.05).

Conclusion DC, mainly mDC, increased significantly in MDS, but pDC did not. The costimulatory molecules(CD80 and CD86) except CD40 expressed more on the DC of MDS patients. It was suggested that the APC relating the inflammatory injury increased in MDS, but the APC relating to antitumour immunity did not. What we found here might be involved into the pathogenesis of MDS.