REPOPULATION OF CIRCULATING T-LYMPHOCYTE, B-LYMPHOCYTE AND NK-LYMPHOCYTE FOLLOWING BONE-MARROW AND BLOOD STEM-CELL TRANSPLANTATION

A variety of T, B and natural killer (NK) cell subsets defined by surf ace markers were analyzed by double immunofluorescence flow cytometry in the peripheral blood of patients following autologous bone marrow t ransplantation (ABMT, n=14), autologous peripheral blood stem cell tra nsplantation (PBSCT, n=10) and allogeneic bone marrow transplantation (allo-BMT, n=6). Patients following ABMT were divided in 2 groups, tho se who did not received G-CSF post-transplant (ABMT, n=6) and those wh o 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(+) s ubset, especially following PBSCT (only decreased at 1 month). A signi ficant expansion of the CD3(+)CD57(+) and CD8(+)CD57(+) phenotypes was noticed between 9 and 12 months following ABMT, the group of longer f ollow-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 CD1 6(+) 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 th ese findings are discussed.