Study on the Subtypes of Dendritic Cells and the Expression of T Cell Co-Stimulating Molecules (CD80, CD86, CD40) on Dendritic Cells and B Cells in the Peripheral Blood of SAA Patients.

Objective To detect the quantities of monocyte-derived dendritic cell precursors (pDC1) and plasmacytoid dendritic cell precursors (pDC2) in peripheral blood mononuclear cells (PBMC) of severe aplastic anemia (SAA) patients before and after immune suppressive therapy (IST), the ratio of their pDC1 to pDC2, and the expression of T-cell co-stimulating molecules (CD80, CD86, CD40) on dentritic cells (DC) and B cells surface in the SAA patients’ peripheral blood.

Methods with three-color monoclonal antibody labeling technology, the quantities and ratio of pDC1 and pDC2 in PBMC were detected in 26 patients with SAA at active phase,13 patients with SAA at recovery phase and 15 normal control respectively by FACS. The aforementioned merits of 10 SAA patients were tested before and 2 months after IST by FACS. By FACS, the expression of CD80, CD86 and CD40 on DC and B lymphocytes were detected in 16 patients with SAA and 15 normal controls.

Results The percentages of total pDC, pDC1, pDC2 and the ratio of pDC1/pDC2 of controls (healthy people) were(0.72±0.32)%,(0.41±0.18)%,(0.30±0.21)%, 1.58±0.69 respectively, and those of the patients with SAA at active phase were(0.96±0.92)%,(0.67±0.65)%,(0.32±0.30)%,2.70±1.63 respectively. The differences were significant [pDC1 (P<0.05); pDC1/pDC2 ratio (P<0.01)]. The aforementioned merits of recuperating SAA patients decreased to (0.77±0.48)%,(0.43±0.37)%,(0.34±0.34)%,1.78±1.29 respectively, which were not significantly different from those of normal control group. The aforementioned merits of 10 SAA patients were(0.87±0.98)%,(0.35±0.30)%,2.65±1.27 before IST, and(0.24±0.28)%,(0.14±0.14)%,2.16±0.82 after IST, with significant decreases of pDC1 and pDC2 (P<0.05). The percentages of CD80, CD86 and CD40 expression on DC in peripheral blood of healthy control were(1.61±2.37)%,(11.97±12.18)%,(0.56±1.26)% respectively, and those of SAA patients were(9.14±12.89)%,(29.84±9.56)%,(7.04±11.99)% respectively. There was a significant difference of CD86 expression (p<0.05) between SAA patient and normal control groups. The percentages of CD19, CD80, CD86 and CD40 expression on lymphocytes in peripheral blood of healthy control group were (9.38±3.18)%,(2.57±1.51)%,(1.86±1.11)%,(7.34±4.21)% respectively, and those of SAA patients were(11.12±9.02)%,(5.17±2.72)%,(5.98±3.84)%,(8.85±9.95)% respectively. There were significant differences of CD80 and CD86 expressions (P<0.05, P<0.01) between SAA and control groups. The percentages of CD80, CD86 and CD40 expression on B lymphocytes of control were(28.22±12.32)%, 8.04±2.27% and(81.6±22.45)% respectively, and those of SAA patients were(23.06±14.9)%,(20.46±11.1)%,(81.57±21.14)% respectively. There was a significant difference of CD86 expression (p<0.05) between patient and control groups.

Conclusion The pDC subtypes were abnormal and the percentage of pDC1 increased in SAA patients, which were associated with the state of this illness. DC and B Lymphocytes in SAA up-regulated the expression of T cell co-stimulating molecules (CD86) that draw the T lymphocyte abnormally activated.