Regeneration of immunity and varicella-zoster virus infection after high-dose chemotherapy and peripheral blood stem cell autografts in children.

We assessed recovery of the immune system in 41 children who underwent high-dose chemotherapy (without total body irradiation) and autologous peripheral blood stem cell transplantation (PBSCT) for acute leukemias or non-Hodgkin's lymphoma. The analysis was in two parts. Firstly, we performed serial monitoring of regenerating subsets and blastogenesis of lymphocytes. We then reviewed the incidence of varicella-zoster virus (VZV) infection, based on the belief that this served as a clinical indication of immunological recovery. The CD4/CD8 ratio markedly decreased in all patients, with a nadir at 3 months, due to both abnormally low levels of CD4+ cells and sustained higher levels of CD8+ cells. These abnormalities were sustained for > 12 months post-graft. Within 6 months after PBSCT, all patients showed a decreased in vitro response to mitogens including PHA, Con A and PWM but these responses gradually recovered during the subsequent 6 months. All patients had a previous history of chicken pox. The actuarial incidence of VZV was 45% at 6 months and 67% at 12 months. All patients were treated with intravenous acyclovir with relief of pain and cutaneous healing within 10 days. No patient developed visceral dissemination. These findings suggest that at least in children, no major difference is apparent between immunological reconstitution in bone marrow transplantation and PBSCT. The development of minor and reversible VZV is a common event in this group of patients.