Transforming growth factor beta (TGF-beta), a potent inhibitor of erythropoiesis: neutralizing TGF-beta antibodies show erythropoietin as a potent stimulator of murine burst-forming unit erythroid colony formation in the absence of a burst-promoting activity

Transforming growth factor beta (TGF-beta) is a bifunctional regulator of the growth of myeloid progenitors and is here demonstrated to directly inhibit the growth of primitive erythroid progenitors by 95% to 100% regardless of the cytokines stimulating growth. Autocrine TGF- beta production of primitive hematopoietic progenitors has previously been reported. In the present study, a neutralizing TGF-beta antibody (anti-TGF-beta) added to serum-containing cultures, resulted in a 3-, 4- , and 25-fold increase in burst-forming unit erythroid (BFU-E) colony formation in response to interleukin-4 (IL-4) plus erythropoietin (Epo), SCF plus Epo, and IL-11 plus Epo, respectively. The growth of BFU-E progenitors has been suggested to require a burst-promoting activity in addition to Epo. Accordingly, we observed no BFU-E colony formation in serum-containing cultures in response to Epo alone. In contrast, 50 BFU-E colonies were formed when anti-TGF-beta was included in the culture. In serum-free cultures, Epo also stimulated BFU-E colony formation in the absence of other cytokines, whereas anti-TGF- beta had no effect on the number of colonies formed. Quantitation of TGF-beta 1 in serum by an enzyme-linked immunosorbent assay method showed predominantly the presence of precursor (latent) TGF-beta 1, but also showed active TGF-beta 1 at a concentration sufficient to potently inhibit erythroid colony formation. Thus, neutralization of active TGF- beta 1 in serum shows that Epo alone is sufficient to stimulate the growth of murine BFU-E progenitors.     

Fluorescent in vivo tracking of hematopoietic cells. Part I. Technical considerations

We report a new technology for in vivo tracking of hematopoietic cells, using fluorescent lipophilic probes. Because the probe is irreversibly bound in the lipids of the cell membrane; substantial numbers of dye molecules can be incorporated per cell and thus substantial signal to noise can be achieved. Although this technology can be used for all hematopoietic cells, these first findings are reported on red blood cells (RBCs) owing to the importance of the membrane to RBC function and integrity. We demonstrated that labeling 10% of the RBCs of a rabbit and reinjecting them into the animal makes possible the tracking of these cells at various times after injection. Furthermore, the labeling appears not to affect in vivo cell lifetime or cellular volume changes in response to hypotonic shock. The single cell fluorescence intensity of the labeled RBCs remains relatively constant for 60 days, and an immune response appears not to be generated against labeled cells. That labeled RBCs have lifetime kinetics in vivo, as shown in other studies, indicates that the membranes are functioning normally and are unaltered by the labeling technology. The technology we present is also applicable to white blood cells, bone marrow, and platelets.     

Paediatric transfusion

Paediatric transfusion encompasses a wide range of clinical circumstances including the consideration of maternal antibodies, the changing nature of the transfusion recipient with respect to growth and development, and the management of inherited conditions which if optimally treated in early life may have problems which are delayed or less severe in adult life. Whilst the transfusion of adults and children has much in common, a child cannot be considered as a scaled down adult; there are many important differences. Developmental changes are most marked in the neonate and, together with the fact that their antibodies are maternally derived, this population provide some of the most striking challenges. The increased use of intra uterine transfusion adds an extra dimension here. A particular paediatric concern is the long-term consequences of transfusion. It is to be hoped that paediatric transfusion recipients will live long enough that any potential problems will manifest themselves, thus the aim must be to minimize transfusion risks.     

The Mr 95,000 gelatin-binding protein in differentiated human macrophages and granulocytes

Cultured adherent human macrophages and a promonocytic cell line, U 937, were previously shown to produce a Mr 95,000 gelatin-binding protein. The protein has no immunologic cross-reactivity with the well- characterized gelatin-binding protein fibronectin and the Mr 70,000 gelatin-binding protein produced by a variety of mesenchymal or epithelial cell types (T. Vartio et al, J Biol Chem 257:8862, 1982). In the present study the Mr 95,000 protein was found in Triton X-100 extracts of granulocytes purified from human blood buffy coat. The protein, as isolated by gelatin-agarose, was immunologically cross- reactive with the corresponding macrophage protein in immunoblotting assay. When peripheral blood and bone marrow cells were examined for the presence of the Mr 95,000 protein by indirect immunofluorescence, positive staining was detected only in differentiated granulocytes but not to any significant extent in metamyelocytes, myelocytes, promyelocytes, or in normal or leukemic blasts. In granulocytes the protein had a granular cytoplasmic distribution. In freshly prepared monocyte cultures, the Mr 95,000 protein was detected in low amounts in the cytoplasm, while along with differentiation of the cells into macrophages, the immunofluorescence increased in a reticular and vesicular cytoplasmic pattern and in a juxtanuclear cap, probably representing the Golgi complex. In conclusion, the Mr 95,000 gelatin- binding protein was specifically detected in macrophages and granulocytes and may thus serve as a differentiation marker for these phagocytic cells.     

Monitoring information processing efficiency after stroke or head injury: A comparison of four computerised tests for use in single case experiments

Abstract

Single case experiments on cognitive rehabilitation can only be valid if adequate methods of monitoring cognitive change are developed. The sensitivity and reliability of four computer-based tests of information processing efficiency (continuous choice reaction time, visual tracking, memory for pairs, and critical flicker fusion) were compared. Performance of 16 left hemisphere stroke patients and 17 patients with severe closed head injury was compared with age-matched controls. The reaction time task proved the most useful in detecting effects of brain damage in both groups and showing good test-retest reliability.     

Transforming growth factor-beta trans-modulates the expression of colony stimulating factor receptors on murine hematopoietic progenitor cell lines

Transforming growth factor beta (TGF-beta) is a potent and selective growth inhibitor of early hematopoietic progenitors and leukemic cells. The cellular mechanism(s) underlying this antiproliferative effect is, however, currently unknown. In the present study, we demonstrate that TGF-beta inhibits the expression of granulocyte-macrophage colony stimulating factor (GM-CSF), interleukin 3 (IL-3), and granulocyte-CSF (G-CSF) receptors on murine factor-dependent and independent hematopoietic progenitor cell lines without a significant change in receptor affinity. A maximum reduction in GM-CSF receptor numbers of 65% to 77% was observed by 96-hour incubation with TGF-beta. The TGF- beta induced trans-down-modulation of GM-CSF receptors was prolonged, noncytotoxic but reversible, and not due to endogenous production of GM- CSF. The TGF-beta induced reduction in CSF receptor numbers preceded TGF-beta's growth inhibitory action. In addition, the ED50 (1 to 10 pmol/L) for TGF-beta's CSF receptor modulatory and antiproliferative effect was similar. The effect of TGF-beta on cell surface CSF receptor expression was specific, because the expression of other cell surface proteins (Ly 5 and Ly 17) was not affected by TGF-beta treatment, and because other growth inhibitors (tumor necrosis factor and interferon) did not affect CSF receptor expression. These data suggest that the downregulation of the growth of hematopoietic progenitor cells by TGF- beta involves reducing the cell surface expression on growth factor receptors.