IMPROVED IMMUNE RECONSTITUTION AFTER ALLOTRANSPLANTATION OF PERIPHERAL-BLOOD STEM-CELLS INSTEAD OF BONE-MARROW

Clinical studies are evaluating possible advantages of allogeneic peri pheral blood stem cell transplantation (PBSCT) over bone marrow transp lantation (BMT). We compared immune reconstitution after PBSCT in = 20 ) and BMT in = 20) in terms of lymphocyte subset counts and proliferat ive in vitro responses to mitogens and recall antigens (follow-up: 5 t o 11 months posttransplant). Additionally, 10 PBSC harvests and 10 mar row harvests were analyzed for their composition of immunocompetent ce lls. Compared with BMT patients, PBSCT recipients had PB counts of nai ve (CD4(+)CD45RA(+)) and memory (CD4(+)CD45R0(+)) helper T cells and o f B cells (CD19(+)) that were elevated (P <.003, P <.001, and P <.004, respectively) and proliferative responses to phytohemagglutinin (P <. 0001), pokeweed mitogen (P <.02), Tetanus toroid (P <.0005), and Candi da (P <.004) that were increased. PBSCT recipients received a mean of 188 (range, 44 to 280) x 10(6) naive helper T cells and 169 (range, 18 to 296) x 10(6) memory helper T cells per kilogram; the corresponding numbers for BMI recipients were 11 (range, 4 to 24) and 10 (range, I to 22) x 10(5) cells per kilogram, respectively. The question of wheth er the documented improved in vitro immune competence after PBSCT is a ssociated with a lower incidence of infectious complications in vivo s till needs further study. (C) 1996 by The American Society of Hematolo gy.