A micro-culture system for cloning human T lymphocytes in agar

Abnormal megakaryopoiesis in patients with myelodysplastic syndromes: analysis of cellular and humoral defects

In 13 patients with myelodysplastic syndrome (MDS) mature and immature erythropoietic (CFU-E, BFU-E), granulopoietic (CFU-GM) and megakaryopoietic (CFU-Meg) colony formation from human bone marrow mononuclear cells was evaluated in a microagar culture system. All but three patients exhibited abnormal CFU-Meg. The defect of CFU-Meg paralleled the reduction of BFU-E, whereas CFU-GM number declined to a lesser extent. Not only the CFU-Meg number, but also the number of megakaryocytes (Mk) per colony was reduced suggesting an additional functional CFU-Meg defect. Megakaryocytic growth factor (Meg-CSF) abnormalities in MDS patients were detected using normal nonadherent T-lymphocyte depleted bone marrow cells as target cells for serum testing. Even for sera from patients with a reduction of platelets and bone marrow megakaryocytes Meg-CSF levels were not increased. No cellular or humoral inhibition could be detected in an MDS patient with a 5q- karyotype, who had an isolated defect of the megakaryocytic cell lineage at presentation. Some patients revealed a spontaneous formation of mixed erythrocytic, granulocytic and megakaryocytic clusters in the presence of fetal calf serum or autologous patient serum, probably representing autonomous proliferation of the malignant clone. In conclusion, both cellular and humoral factors can cause abnormalities of the megakaryocytic cell lineage in MDS patients.

Progressive preleukemia presenting amegakaryocytic thrombocytopenic purpura: association of the 5q- syndrome with a decreased megakaryocytic colony formation and a defective production of Meg-CSF

The authors present a patient with the typical clinical picture of an acquired amegakaryocytic thrombocytopenic purpura. After 16 months of observation, the patient developed acute myelomonocytic leukemia. During the preleukemic phase and after progression to overt leukemia, serial in-vitro analyses of megakaryocytic, granulocytic, erythrocytic and T-lymphocytic colony growth were carried out in a microagar culture system. At presentation, a marked diminution of CFU-M was observed, whereas CFU-E, BFU-E, CFU-C and CFU-TL were in the normal range. The CFU-M number remained at its low level during the whole observation period. The CFU-C number declined steadily during the preleukemic period, while BFU-E, CFU-E and CFU-TL remained constant until January 1985 when the patient developed AML. After progression to overt leukemia, a distinct reduction became evident in all colony-forming cells. Cytogenetic studies performed during the preleukemic phase indicated the presence of a 5q- chromosome. The authors submit evidence here that the patient was not only characterized by defective megakaryocytic colony formation but also by a deficiency of functional megakaryocyte colony-stimulating activity. No humoral or cellular inhibitors of CFU-M colony formation were found. It is concluded that in preleukemia with a 5q- chromosome the megakaryocytic cell lineage may be involved in the process that precedes overt leukemia at an earlier time than cells of granulocytic and erythrocytic lineages. In addition, it is shown here that megakaryocytopoiesis during the preleukemic period can be characterized by two different defects: first, an intrinsic megakaryocytic stem cell defect and, second, a deficiency of functional megakaryocytic colony-stimulating activity.

Suppressed colony formation of peripheral blood lymphocytes in a patient with somatostatinoma

The in vitro clonal growth of T lymphocytes was examined in a patient with somatostatinoma over a period of 8 months. After phytohemagglutinin stimulation colony-forming unit T lymphocytes could not be detected as compared to healthy controls and patients with metastatic colon tumors. The somatostatin produced by this tumor was identified as somatostatin-14. Synthetic somatostatin-14 inhibits significantly the colony formation and the tritiated thymidine incorporation of human peripheral T lymphocytes obtained from healthy subjects, suggesting immunoregulative properties of this neuroendocrine peptide.

A regulatory role of activated T-lymphocytes on human megakaryocytopoiesis in vitro

Cellular interactions responsible for regulating in vitro megakaryocytopoiesis were studied using a microagar culture system which permits the simultaneous proliferation of human megakaryocytic progenitor cells (CFU-M) and T-lymphocytic colonies (CFU-TL). The proliferation of these colony types depends mainly on two factors: phytohaemagglutinin (PHA) and erythropoietin (EP). The direct addition of increasing PHA concentrations to the liquid overlayer resulted in a parallel increase of CFU-M and CFU-TL. If the T-lymphocytes were removed by an E-rosetting technique a marked diminution of CFU-M and CFU-TL numbers was observed. However, monocyte depletion resulted in a marked augmentation of CFU-M proliferation compared to unfractionated mononuclear cells. In order to confirm that the reduction of CFU-M proliferation observed after T-depletion was primarily mediated by the absence of T-lymphocytes, we have co-cultured different concentrations of previously removed autologous T-lymphocytes with a constant number of T-depleted bone marrow cells. A parallel increase of CFU-TL and CFU-M was found if 0.75 - 7.5 X 10(4) T-lymphocytes were added to the culture. In conclusion, our results indicate that activated T-lymphocytes augment proliferation of human bone marrow CFU-M and that monocytes are less important for the growth of megakaryocytic colonies.

Subpopulations of colony-forming B lymphocytes exhibit distinct in vitro growth characteristics

Human peripheral blood cells enriched for B lymphocytes were stimulated to focal proliferation in semisolid cultures with lymphocyte-conditioned media, Protein A (Prot A), lipopolysaccharide (LPS) and 2-mercaptoethanol (2-ME). After 6-8 days of incubation, two morphologically distinct colony types were observed. Type I colonies were diffusely proliferating aggregates within the agar layer, whereas another subset of B-cell-colony-forming cells (CFU-BL) formed round compact type II colonies which appeared to leave the agar layer and continued to proliferate in the liquid overlayer of our culture system. They reached maximum proliferation 2 days earlier than type I colonies. Cells derived from both colony types were positively identified as B lymphocytes by monoclonal antibodies using immunoperoxidase staining. In addition to this distinct growth pattern, both colony types exhibited different proliferative responses which were dependent on the kind of conditioned media used and the mitogen concentration. In secondary cultures both type I and type II colony-derived cells showed recloning capacity. However, after replating, both colony types gave rise to round compact type II colonies. These results demonstrate that there exist at least two subpopulations of colony-forming B lymphocytes, possibly one more primitive than the other, which can be distinguished by in vitro growth characteristics.

Myelopoiesis of human bone marrow cells in a micro-agar culture system: comparison of two sources of colony stimulating activity (CSA)

Human bone marrow cells were grown in a micro-agar culture system in the presence of human placenta (HPCM) and giant cell tumor conditioned media (GCT). The effects of HPCM and GCT conditioned media on linearity, growth dynamics, and morphological composition of colonies were studied after 7 and 14 days of incubation. Under the described conditions the dose-response curves for HPCM and GCT were different: on day 7 maximal stimulation was obtained with 2.5% HPCM and 20% GCT; on day 14 a maximal response was reached with 1.25% HPCM and 5% GCT. Both stimuli produced maximal growth after 7 days of incubation, followed by a rapid decrease in the number of formed colonies up to day 14. The morphological study of aggregates showed that after 7 days of incubation 80% pure granulocyte and 20% mixed granulocyte-macrophage colonies were found in the presence of both stimuli. However, on day 14 the incidence of granulocyte-macrophage colonies increased to 60%, whereas the percentage of pure granulocyte colonies decreased to 20%. The frequency of eosinophil colonies was relatively low (median 15%) with both stimuli. The described system can be applied successfully for studies of myelopoiesis in vitro. Both sources of colony stimulating activitites (CSA) employed had no significant difference in their ability to stimulate myelopoiesis.

Clonal growth of human megakaryocytic progenitor cells in a micro-agar culture system: simultaneous proliferation of megakaryocytic, granulocytic, and erythroid progenitor cells (CFU-M, CFU-C, BFU-E) and T-lymphocytic colonies (CFU-TL)

A simple and reproducible micro-agar culture technique for cloning human CFU-M is described. Human bone marrow mononuclear cells were suspended in agar and incubated for 12 days. Stimulation was provided by the direct addition of phytohemagglutinin-P (PHA-P), erythropoietin (Epo) and 2-mercaptoethanol (2-ME) to the liquid overlayer. A shift from BFU-E and CFU-C proliferation to CFU-M and CFU-TL was observed with increasing PHA concentrations. Under optimal conditions (PHA 50 micrograms, Epo 1.2 IU, 2-ME 2 x 10(-4) M, 1% purified BSA, 0.04% human transferrin, saturated with Fe C13) a linear relationship between colonies formed and plated cell number were observed. For the routine morphological analysis, the whole agar layers were stained using the Pappenheim method. For further characterization of CFU-M, cytochemical stainings and immunofluorescence tests with rabbit-antihuman factor VIII-related antigen were performed on the whole agar layers.