Clinical significance of cytostasis activity of mononuclear cells in childhood acute lymphoblastic leukemia

Cytostasis activity of mononuclear cells (MNC) was studied in 32 children with acute lymphoblastic leukemia (ALL) with special reference to the relapse of the disease. MNC from ALL even in complete remission had decreased cytostasis activity. The cytostasis activity in ALL patients who relapsed within 3 months after the assay was significantly lower than that of the patients who continued to be in remission for more than 6 months after the assay. Serial assays in six patients demonstrated that a sudden decrease of the cytostasis activity occurred 4 to 8 weeks before the relapse when there were no apparent changes of the peripheral blood cell counts and bone marrow pictures. When relapsed, the cytostasis activity was markedly impaired. These results demonstrate that the assay of MNC cytostasis activity is a useful tool to predict or detect relapse of ALL at an earlier time. The cytostasis activity was still decreased after the cessation of chemotherapy for ALL, demonstrating a characteristic immunologic defect in ALL.