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 autologou s peripheral blood stem cell transplantation (PBSCT) for acute leukemi as or non-Hodgkin's lymphoma. The analysis was in two parts. Firstly, we performed serial monitoring of regenerating subsets and blastogenes is of lymphocytes. We then reviewed the incidence of varicella-zoster virus (VZV) infection, based on the belief that this served as a clini cal indication of immunological recovery. The CD4/CD8 ratio markedly d ecreased in all patients, with a nadir at 3 months, due to both abnorm ally 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 4 5% at 6 months and 67% at 12 months. All patients were treated with in travenous acyclovir with relief of pain and cutaneous healing within 1 0 days. No patient developed visceral dissemination. These findings su ggest that at least in children, no major difference is apparent betwe en immunological reconstitution in bone marrow transplantation and PBS CT. The development of minor and reversible VZV is a common event in t his group of patients.