Monoclonal antibody detects embryonic epitope specific for nerve-derived transferrin

Effects of ovotransferrin on chicken macrophages and heterophil-granulocytes

Ovotransferrin (OTF) is an acute phase protein in chickens, serum levels of which increase in inflammation and infections. To understand the significance of OTF in inflammation, we studied its in vitro effects on HD11 cells, a macrophage cell line, and heterophils isolated from blood using a panel of variables indicative of cellular activation. These included the production of interleukin-6 (IL-6), nitrite, matrix metalloproteinase (MMP), oxidation of dichlorofluorescein diacetate for respiratory burst and the degranulation of heterophils by the loss of fluorescein isothiocyanate positive cytoplasmic granules. The results show that ovotransferrin stimulates the production of IL-6, nitrite and MMP by HD11 cells and augments phorbol ester-induced respiratory burst. Ovotransferrin stimulated heterophils to produce IL-6, and MMP, but failed to produce nitrite, enhanced respiratory burst activity and degranulation. These results suggest that ovotransferrin can modulate macrophage and heterophil functions in chickens.

Changes in serum ovotransferrin levels in chickens with experimentally induced inflammation and diseases

A competitive enzyme immunoassay was developed to measure the changes in serum levels of ovotransferrin (OTF) during inflammation and infectious diseases in chickens. The assay is based on the competition of serum OTF with a fixed concentration of biotin-labeled OTF to bind to a rabbit anti-chicken transferrin antibody immobilized on microtiter wells. After several washing steps, the antibody-bound biotinylated OTF is probed with streptavidin-horseradish peroxidase conjugate (HRP) followed by a colorimetric detection of the HRP activity. The relative changes in the optical density of color are plotted against the competing concentrations of OTF with logarithmic regression to generate a standard curve that is used to determine the concentrations of OTF in unknown samples. Serum had no effect on the measurement of OTE By this method, the time course changes of serum OTF levels in 4-wk-old male broiler chickens that were subjected to inflammation by croton oil injection were measured. The results showed croton oil-induced inflammation elevated serum OTF levels at 16 hr postinjection. OTF levels reached a peak by 72 hr, remained high through 120 hr, and returned to a basal level of olive oil-injected controls by 240 hr. There were no changes in serum OTF levels at any of the above time points in olive oil-injected control chickens. For studies with poultry diseases, specific-pathogen-free (SPF) male chickens were challenged with known bacterial and viral pathogens, and serum was collected at the height of the infection, i.e., 7 days after the challenge. Compared with uninjected controls, the SPF chickens challenged with Escherichia coli, fowl poxvirus, respiratory enteric orphan virus, infectious bursal disease virus, infectious bronchitis virus, or infectious laryngotracheitis virus had higher levels of OTF in serum. Inflammation-induced changes in serum OTF levels were also evident in the changes in the density of a 65-kD band protein corresponding to OTF. These results demonstrate that serum OTF may be a nonspecific clinical marker of inflammation associated with traumatic or infectious avian diseases.

Improving medical approaches to primary CNS malignancies--retinoid therapy and more

Successfully inducing differentiation in ectodermal diseases, retinoids harbour considerable therapeutic potential in the treatment of neuroectodermal-neuroepithelial malignancies. The principal tissue retinoid, retinoic acid, can be potently upregulated in vivo by a relatively specific catabolic inhibitor, R75251 (liarozole). Both substances have been given orally over 2 years in addition to standard treatment, and have been well tolerated. Corresponding closely to plasma retinoid levels, cutaneous side effects facilitate individual dosing. We evaluate this adjuvant retinoid approach and additional efforts to improve therapy of primary CNS malignancies, including the topical administration of retinoids in gamma linolenic acid.

Clear cell carcinoma of the human ovary synthesizes and secretes a transferrin with microheterogeneity of lectin affinity

Human ovarian clear cell carcinoma cell line (transferrin (Tf)-non-producer), HAC 2, cells were adapted to grow in chemically defined synthetic medium when the cells were cultured with medium containing 10 micrograms/ml of insulin at least for 6 months. They synthesized and secreted constantly the 80 kDa protein immunologically similar to human serum Tf (15 +/- 12 ng/ml/10(7) cells/3 days). By sensitive lectin-affinity electrophoresis followed by antibody-affinity blotting technique, a concanavalin A weakly bound or unbound, lentil lectin, a strongly reactive abnormal band, which was rarely found in human serum Tf, was detectable in the Tf synthesized by HAC 2 cells (HACTf). These findings suggest that the HACTf may act as one of the autocrine growth factors and that this heterogeneity of HACTf for lectin affinity is ascribed to differences in the carbohydrate moiety of the Tf.

The biology of transferrin

The chemistry and molecular biology of transferrin is discussed. The discussion covers the genetic control of transferrin synthesis, its intracellular synthesis, intra- and extracellular transport, and its interaction with transferrin receptors. The role of transferrin in iron metabolism is evaluated, both with regard to iron uptake by transferrin as to iron uptake from transferrin by different cells. The knowledge on the biochemical mechanisms involved in iron uptake is presented, with special reference to the triple role of the acidification of endocytotic vesicles. Apart from its traditional role in iron metabolism, transferrin acts as a growth factor. A distinction of two groups of growth-stimulating properties of transferrin has been made. As an early effect, membranous and intracellular changes are initiated, possibly based on electrochemical effects on the cell. The late effects seem to relate to its role in iron transport. Interestingly, the early growth stimulating effects can be segregated from the former function of transferrin and strictly speaking neither depend on iron nor on the transferrin molecule itself. Also the trophic effect of transferrin on several cell types has been described. Hypotheses concerning the biochemical basis of this effect are presented and within this context a new hypothesis on the differential occupation of iron binding sites of serum transferrin is forwarded. Examples of the applicability of present understanding of the biology of transferrin in clinical settings are presented.