Peripheral T-cell expansion and low infection rate after reduced-intensity conditioning and allogeneic blood stem cell transplantation.
Peripheral blood stem cell transplantation after reduced-intensity conditioning (RIC-PBSCT) regimen is an alternative to conventional regimens with less immediate toxicity. Since immune recovery is of crucial importance for the control of infections, we retrospectively studied the recovery of T-, B- and NK cell subsets in 20 consecutive patients undergoing RIC-PBSCT. We also studied the thymic output using T-cell receptor excision circle assay. Engraftment was rapid and few infectious complications were seen: three early (before 2.5 months) cases of asymptomatic cytomegalovirus reactivation, two late Gram-negative bacterial infections and no fungal infection. While CD4+ T-cell reconstitution was slow, CD8+ T-cell counts were close to normal values at 4 months. Median CD19+ B-cell counts reached normal values at 11 months. Rapid CD56+ NK cell reconstitution was noticed as early as 1.5 months. Low T-cell receptor excision circle numbers and preponderance of memory-type subsets among T cells further suggested that CD8+ T-cell reconstitution resulted predominantly from peripheral expansion and that thymic-dependent reconstitution was severely impaired. In conclusion, large peripheral T-cell expansion may compensate for late thymic-dependent lymphopoiesis, and may, with other factors such as NK and B-cell reconstitution and careful antiinfectious prophylaxis, help limit the incidence of severe infections after RIC-PBSCT.
Larosa
F
F
Department of Hematology. Centre Hospitalo-Universitaire Jean Minjoz, Besançon Cedex, France. flarosa@chu-besancon.fr
Marmier
C
C
Robinet
E
E
Ferrand
C
C
Saas
P
P
Deconinck
E
E
Bulabois
C-E
CE
Rohrlich
P-S
PS
Ledu
K
K
Helias
P
P
Tiberghien
P
P
Cahn
J-Y
JY
D000328:Adult; D000368:Aged; D001402:B-Lymphocytes; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D003586:Cytomegalovirus Infections / Q000276:immunology / Q000821:virology; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000276:immunology / Q000382:microbiology; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology; D016131:Lymphocyte Subsets / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D036102:Peripheral Blood Stem Cell Transplantation; D020127:Recovery of Function / Q000276:immunology*; D019172:Transplantation Conditioning / Q000379:methods; D014184:Transplantation, Homologous