Repopulation of circulating T, B and NK lymphocytes following bone marrow and blood stem cell transplantation

A variety of T, B and natural killer (NK) cell subsets defined by surface markers were analyzed by double immunofluorescence flow cytometry in the peripheral blood of patients following autologous bone marrow transplantation (ABMT, n=14), autologous peripheral blood stem cell transplantation (PBSCT, n=10) and allogeneic bone marrow transplantation (allo-BMT, n=6). Patients following ABMT were divided in 2 groups, those who did not received G-CSF post-transplant (ABMT, n=6) and those who did (ABMT+G, n=8). All patients following PBSCT or allo BMT received G-CSF. In all the groups prolonged significant decreases with respect to normal numbers were observed for the T CD3(+), CD2(+) and CD25(+) subsets, more profound for the CD4(+) subset but less for the CD8(+) subset, especially following PBSCT (only decreased at 1 month). A significant expansion of the CD3(+)CD57(+) and CD8(+)CD57(+) phenotypes was noticed between 9 and 12 months following ABMT, the group of longer follow-up. Long-lasting expansion of the NK-like CD3(+)CD56(+) and CD3(+)CD16(+) subsets was also observed. The B CD19(+) and CD20(+) subsets had a significant overexpression from 4 months after ABMT, showing a normally balanced Igk(+): Ig1(+) ratio. Concordantly, the HLA-DR+ and HLA-DQ(+) subsets showed significant increases. The NK CD56(+) and CD16(+) subsets had a faster recovery than the T or B subsets in all the groups. However, the CD3(-)CD56(+), CD3(-)CD16(+), CD16(+)CD56(+), CD3(-)CD8(+), and especially the CD3(-)CD57(+), CD16(+)CD57(+), and CD56(+)CD57(+) subsets had a slower recovery than the global CD56(+), CD16(+), or CD57(+) subsets. The biological and clinical implications of these findings are discussed.