Red blood cell (RBC) fractions were studied after separation of whole blood by means of counterflow centrifugation, Percoll column (Pharmacia, Uppsala, Sweden), and a combination of both separation techniques. Mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular hemoglobin (MCH), and hemoglobin A1c (HbA1c) were measured in each fraction. From the results it was obvious that the combination of both techniques was the best separation technique of these three. MCV had a good correlation with cell age as measured with HbA1c concentration gradient; MCH and MCHC less so. MCV and MCH decreased in parallel to an increase in HbA1c. MCHC increased with increasing HbA1c. From these data it is concluded that there is a steadily ongoing loss of cellular hemoglobin and proportionally more cellular water during the life of the RBC.

Interleukin-4 (IL-4) modulates the survival, proliferation, and differentiation of a variety of hematopoietic cells. The effects are mediated through a single class of high-affinity receptors for IL-4. To understand the biologic effects of IL-4 on human T cells, we studied the regulation of IL-4 receptor (IL-4R) gene expression. We showed that IL-4R mRNA accumulation in human T cells is enhanced fourfold after activation of different secondary signaling pathways by concanavalin A (Con A), phorbol myristate acetate (PMA), the calcium ionophore A23187, and combinations of these factors. This could be ascribed to an increase in the IL-4R transcription rate and to stabilization of IL-4R mRNA resulting in a half-life of 80 to 90 minutes (v 35 to 40 minutes in resting T cells). IL-4 did enhance the IL-4R mRNA accumulation by a factor 10, which was caused by an increase in the IL-4R transcription rate and prolonging the half-life of IL-4R transcripts to 140 to 160 minutes. Finally, it was shown that A23187 induced IL-4R mRNA expression is a protein synthesis-dependent process. In contrast, Con A- , PMA-, Con A + PMA-, and Con A + A23187-induced expression of IL-4R mRNA is protein-synthesis independent. Cyclosporine A inhibited the A23187- and Con A + A23187-induced IL-4R mRNA accumulation, whereas Con A-, PMA-, and Con A + PMA-induced IL-4R mRNA expression was not affected by this drug. These data indicate that expression of IL-4 receptors on human T cells can be modulated by different intracellular signaling pathways at both transcriptional and posttranscriptional levels.

A patient with acute promyelocytic leukemia (APL) and laboratory evidence of fibrinolysis who could not be treated with aggressive cytostatic regimens because of Aspergillus pneumonia was treated with cis-retinoic acid (RA), a substance that can induce differentiation and maturation of APL cells. After seven weeks of daily oral treatment, he went into complete remission, and signs of coagulopathy disappeared. Meanwhile, the Aspergillus pneumonia could be treated adequately. Based on the experience in this single patient, RA deserves further evaluation in the treatment of APL.

Human recombinant interleukin-4 (IL-4) was studied for its effects on myeloid progenitor cells from normal and leukemic bone marrow cells in the presence and absence of additional growth factors. IL-4 itself did not support myeloid cluster or colony formation (CFU-GM). However, cultures supplied with IL-4 (300 U/mL) and IL-3 demonstrated a significant decline in myeloid colony numbers (CFU-GM) compared with the effects of IL-3 alone: (48 +/- 27 v 88 +/- 27 CFU-GM/10(5) MNC). In contrast, IL-4 augmented the G-CSF-supported CFU-GM: (80 +/- 31 v 148 +/- 52 CFU-GM/10(5) MNC). The effects of IL-4 were not mediated by accessory cells because similar results were obtained with and without T-cell, B-cell, or adherent depleted cell fractions. Morphologic analysis of clusters (day 7) and the colonies (day 14) demonstrated that IL-4 enhanced myeloid colony formation in the presence of G-CSF, whereas the cultures supplied with IL-3 and IL-4 did not show a lineage- restricted decline of CFU-GM. A heterogeneity in growth response was observed in the leukemic counterpart. With the 3H-thymidine proliferation assay, IL-4 augmented the G-CSF-induced proliferation of acute myeloid leukemic (AML) cells in 4 of the 12 cases, while the IL-3- supported proliferation was antagonized in 3 of the 12 cases. In the blast colony assay, IL-4 suppressed the IL-3-supported AML-CFU in the majority of cases, but enhanced the G-CSF stimulated AML-CFU in 3 of 6 cases. These data demonstrate divergent effects of IL-4 on the normal myeloid progenitor cell in the presence of IL-3 or G-CSF, while a variability in responsiveness is observed in the leukemic counterpart.

Summary. The characteristics of large, abnormal cells in the peripheral blood of patients with Hodgkin's disease have been investigated with cytochemical stains. It was possible to distinguish clearly cells of the granulocytic series, megakaryocyte parts, cells of the mononuclear phagocytic system and immunoblasts. These cells, however, are not specific for Hodgkin's disease, for they could also be found in normal subjects, in patients with infectious mononucleosis or cytomegalovirus disease and patients with lympho‐ or reticulosarcoma. Cells considered to indicate dissemination of Hodgkin's disease could only be detected in the peripheral blood of patients with this condition, and not in the other diseases mentioned above. These cells do not react with the periodic acid Schiff stain, Sudan black, peroxidase, non‐specific esterase and sometimes faintly with methyl green pyronin. It is therefore improbable that these cells belong to the categories of the granulocytic or monocytic cells, but a relationship to the lymphoid cells on the one hand or to the reticulum cells on the other could not be excluded on the basis of this morphological investigation.