[Study on the peripheral blood dendritic cells subtypes and the expression of co-stimulating molecules on dendritic cells and B cells in severe aplastic anemia patients].

Objective: To investigate 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 the pDC1 to pDC2, and the expression of co-stimulating molecules (CD80, CD86, CD40) on dendritic cells (DC) and B cells in SAA patients.

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

Results: The percentages of pDC1 and the ratio of pDC1/pDC2 of controls were (0.41 +/- 0.05)% and 1.58 +/- 0.18 respectively, and those of SAA patients at active phase were (0.67 +/- 0.13)% and 2.70 +/- 0.32 respectively, [pDC1 (P < 0.05); pDC1/ pDC2 ratio (P < 0.01)]. The aforementioned parameters in convalescent SAA patients decreased to (0.43 +/- 0.10)%, and 1.78 +/- 0.36 respectively, being no difference from those of normal controls. The percentages of pDC1 and pDC2 in 10 SAA patients were (0.87 +/- 0.31)%, and (0.35 +/- 0.09)%, before IST, and (0.24 +/- 0.09)%, (0.14 +/- 0.04)%, after IST, being significantly decreased (P < 0.05). The percentages of CD86 expression on DC of controls was (11.97 +/- 4.31)%, and that of SAA patients was (29.84 +/- 3.02) % (P < 0.05). The percentages of CD80, CD40 and CD86 expression on lymphocytes of controls were (2.57 +/- 0.44)%, (7.34 +/- 1.22)% and (1.86 +/- 1.11)%, respectively, and those of SAA patients were (5.17 +/- 0.68)%, (8.85 +/- 2.94)% and (5.98 +/- 0.96)% respectively (P < 0.05, P < 0.01). The percentage of CD86 expression on B lymphocytes in controls was 8.04 +/- 0.66%, and in SAA patients was (20.46 +/- 2.78)%, (P < 0.05).

Conclusion: The pDC subtypes were abnormal and the percentage of pDC1 is increased in SAA patients, which are associated with stage of this disease. DC and B Lymphocytes in SAA patients upregulated expression of costimulatory molecules (CD86) which cause the T lymphocyte abnormally activated.