Monitoring of Dendritic Cell Numbers in Patients during the Treatment of Multiple Myeloma.

Objective: In this study, the proportion of dendritic cell (DC) subsets (myeloid DC1 and plasmacytoid DC2), T cells, B cells and NK cells was evaluated in peripheral blood of patients with multiple myeloma (MM) before and during treatment including autologous transplantation. Also control group of healthy volunteers was evaluated.

Methods: Flow cytometric determination of relative cells number in unmanipulated peripheral blood was based on expression of the surface antigen: T cells (CD3/CD4/CD8), B cells (CD19/CD20), NK cells (CD3/CD16/CD56) and DC (CD83/HLA-DR/CD11c and CD83/HLA-DR/CD123).

Results: Significant difference (p<0.01) was found in initial values of CD83⁺ cells between the group of healthy volunteers (n = 15; mean count of CD83⁺ cells 0,26 ± 0,15%; ratio DC1/DC2 = 1,54) and the group of patients before treatment (n = 15; 0,15 ± 0,03% CD83⁺; DC1/DC2 = 4,55). After induction treatment with VAD regimen (vincristine, adriamycin, dexamethasone) in a group of patients was the mean percentage of DC higher (0,18 ± 0,04% CD83⁺ cells; DC1/DC2 = 4,77) than initial values. Administration of G-CSF again increased the total DC numbers (0,34 ± 0,11%; DC1/DC2 = 2,3) and intermediate levels of DC counts were found in the apheresis products (0,22 ± 0,05%; DC1/DC2 = 1,21). After engraftment there were found the highest relative DC numbers (0,50 ± 0,21%; DC1/DC2 = 1,85) in patients. Within six months after transplantation were achieved pretreatment DC values when compared with DC values of healthy volunteers (p<0,97) (0,24 ± 0,08%; DC1/DC2 = 1,57). Total numbers of T cells did not significantly differ during treatment only the reverse CD4/CD8 ratio was found in majority of patients within six month after the transplantation.

Conclusions: Untreated patients with MM have significant lower relative numbers of peripheral blood DC in comparison with healthy volunteers. The highest number of total DC was found after engraftment. The ratio DC1/DC2 showed relative majority of DC1 subtype and its the lowest value was found in the apheresis products. Normal DC values comparable with DC values of healthy volunteers were found in patients within six months after transplantation together with the reverse CD4/CD8 ratio.