Reduced leucine catabolism induced by chemotherapy in leukemic children

Five normal children, four children on chemotherapy, and two children who had completed chemotherapy within a year were studied using 13C-leucine breath test. 13C-Leucine was administered on an empty stomach and a single breath was collected sequentially over 3 h. The cumulative dose of 13C in expired gas was measured and found to be lower in children who had had chemotherapy than in the normal children. These results suggest that chemotherapy may lead to a reduction in leucine catabolism.

Characterization of a nuclear antigen (Mr 150,000) associated with cell proliferation

In the course of development of a "library" of monoclonal antibodies to nucleolar proteins, a monoclonal antibody to a nuclear antigen with a molecular weight of 150,000 was obtained. Using this monoclonal antibody as an immunocytochemical probe, low immunofluorescence was demonstrated in human peripheral blood lymphocytes or HL-60 cells treated with retinoic acid. In contrast, a high degree of immunofluorescence was detected in rapidly proliferating human cells (HeLa, Hep-2, HL-60), in Novikoff hepatoma cells, and in phytohemagglutinin-activated human blood lymphocytes. Immunodot blot analysis indicated there were low levels of Mr 150,000 protein in quiescent lymphocytes and increasing amounts after stimulation with phytohemagglutinin. The increased level of Mr 150,000 protein thus is associated with cell proliferation.

Differential effects of 18- and 24-Gy cranial irradiation on growth rate and growth hormone release in children with prolonged survival after acute lymphocytic leukemia

To evaluate the effects of two different doses of cranial irradiation on growth and growth hormone (GH) release, we studied 61 children with acute lymphocytic leukemia who had survived at least five years in continuous complete remission. Forty-three children received 24 Gy (group 1) and 18 children received 18 Gy (group 2). Height was evaluated at diagnosis, at the end of treatment, and 6, 12, and 24 months later. Growth hormone release was evaluated by arginine and levodopa tests after the end of treatment. After diagnosis, the height SD score decreased significantly in both groups; two years after the end of treatment, only group 1 showed an SD score for height that was still significantly lower than at diagnosis. Group 1 showed impaired GH responses to the tests and, compared with controls, group 1 in fact included a percentage of subjects with a normal response to levodopa (ie, greater than 8 micrograms/L) that was significantly lower (56.4% vs 83.3%) and a percentage of nonresponders to both tests that was significantly higher (21.6% vs 0%). These data indicate that only patients treated with lower cranial irradiation dosage (18 Gy) had complete growth recovery and normal GH responses to pharmacologic tests.

Phorbol ester induces expression and function of interleukin-2 receptors on a human leukemic cell line with a T-cell precursor phenotype

We show here that a human leukemic cell line, PER-117, bearing the markers of a T-cell precursor phenotype, can be induced to express receptors for interleukin-2 (IL-2). These IL-2 receptors could be demonstrated to mediate a physiologic response to the lymphokine for which the high-affinity form of the IL-2 receptor appears to be essential. The phenotype of PER-117 cells corresponds to the earliest identifiable stage of T-cell differentiation, which is defined by the lack of the T3-T-cell receptor complex and the presence of the 40 Kd protein recognized by monoclonal antibodies of the CD7 group. Further evidence for the clonality and T-cell lineage of this cell line was obtained by analysis of rearrangements of genes for the T-cell receptor (TCR) beta chain and for the immunoglobulin heavy-chain (IgJH) genes. PER-117 cells could be shown to have rearranged TCR beta genes but no rearrangement of the IgJH genes. Cell line PER-117 provides a model to investigate the requirements for induction of IL-2 receptors in a cell expressing the first T-cell-specific marker and may help to elucidate the role of IL-2 during thymic differentiation and in the uncontrolled proliferation of T-cell leukemias.

Ricin binding and protein synthesis inhibition in human hematopoietic cell lines

Previous studies showed that human blood cells exhibited varying sensitivities to ricin. To investigate the basis for these differences, ricin binding to human hematopoietic cell lines was assessed and correlated with in vitro ricin sensitivities. Resistant mutants were also isolated and characterized. Ricin binding to CEM cells was rapid, time-dependent, and blocked by unlabeled ricin, but not albumin; ricin binding approached saturation at 3 mumol/L. Scatchard analyses showed multiple classes of binding sites, with maximum and minimum Kd values estimated at 1.5 x 10(-8) mol/L and 2.5 x 10(-7) mol/L. At 4 degrees C, membrane-bound ricin dissociated slowly from the cell surface in the presence of unlabeled ricin, but greater than 95% of the surface-bound ricin was removed with 0.1 mol/L lactose. At 37 degrees C, ricin dissociated from the cell surface with biphasic kinetics. Ricin uptake at 37 degrees C increased linearly for 15 to 30 minutes and plateaued at levels representing 12% to 29% of the amount of ricin bound at 4 degrees C, depending on the cell line. Ricin binding at 4 degrees C varied two- to fivefold among hematopoietic cell lines and was reduced approximately tenfold by incubation with lactose. When compared with parent CEM cells, ricin-resistant CEM variants showed a greater than 95% reduction in ricin binding and showed no detectable binding with lactose added. However, these cells were as sensitive as parent CEM cells to an anti-T-cell ricin immunoconjugate. For all cells examined, there was a close correlation (r = +.9) between ricin bound per cell and in vitro ricin sensitivity. Human hematopoietic cells show widely varying ricin binding, indicating major differences in the carbohydrate content or structure of surface glycoproteins and glycolipids. These variations are probably the major determinant of nonspecific toxicity of ricin immunoconjugates.

Alteration of beta-2-microglobulin level in malignant lymphoproliferative diseases after a high dose of alpha-2-recombinant interferon

A group of 10 patients with malignant lymphoproliferative diseases resistant to any standard therapeutical modalities were treated with a high dose of alpha-2-recombinant interferon (alpha-2-rIF). Alpha-2-rIF was administered at a total dose of 120 x 10(6) IU in a continuous infusion during 48 h. Two cycles of alpha-2-rIF immunotherapy were employed with an interval of 1 month in between each. Serum and urinary beta-2-microglobulin (B2M) were examined prior to alpha-2-rIF application and on days 2, 4, 6 afterwards. Alpha-2-rIF treatment induced an increase in serum B2M as noted on day 2 followed by a decline to below the normal range. The initial increased value was significantly higher as compared to either the pretreatment value or the normal physiological range. The reduced B2M serum level was protracted and lasted until the second cycle of treatment. Similar but not so great changes in B2M serum values were noted during the second application of alpha-2-rIF. The changes of B2M level in the urine, although less convincing, mimic those observed in the serum. The present results confirmed the biological activity of alpha-2-rIF in malignant lymphoproliferative diseases.

Influence of food intake on bioavailability of oral 6-mercaptopurine in children with acute lymphoblastic leukemia

Plasma levels of 6-mercaptopurine (6-MP) were measured after oral administration in 17 children with acute lymphoblastic leukemia (ALL). In the fasting state or after a breakfast consisting of 250 ml milk and 50 g biscuits, 6-MP was administered at a dose of 75 mg/m2. In patients studied in a fasting state, the mean time to plasma peak (tmax) level was 1.2 h, whereas in patient studied after breakfast the mean tmax was 2.3 h. This difference is statistically significant (p less than 0.001). Moreover, the 6-MP peak plasma concentration (cmax) and the areas under the plasma concentration time curves (AUC) were significantly reduced when the drug was administered after breakfast. The mean Cmax +/- SD were 0.98 +/- 0.54 microM and 0.63 +/- 0.48 microM, respectively (p less than 0.05). The mean 6-MP AUC +/- SD in patients studied in a fasting state and after breakfast were 143 +/- 69 microM min and 105 +/- 68 microM, respectively (p less than 0.01). These results indicated that 6-MP should be taken in a fasting state to optimize drug absorption in children undergoing chemotherapy for ALL.