Transferrin receptor expression in reactive and neoplastic lesions of lymphnodes.

Transferrin, the major iron binding protein in human plasma transports iron to various tissues. The first step in cellular iron uptake is binding of transferrin complex to the cell surface membrane by specific molecule known as transferrin receptors. Transferrin receptors are found in limited sites in normal tissues, in contrast, the receptors are widely distributed in majority of carcinomas and sarcomas. Presence of increased transferrin receptors implies a stage of moderate or less differentiation corresponding to elevated proliferative activity and therefore, has a prognostic value. Demonstration of transferrin receptors and its distribution pattern within a tumour as well as its quantitative determination can provide data helpful for, both, an additional understanding of tumour biology and as an approach for planning therapy. In present study, we analysed 60 cases, 30 each of reactive lymphadenitis and lymphomas for transferrin receptors using immunohistochemical technique (DAKO, Code-K0673). Grade II and Grade III intensity was recorded in the germinal centers and the histiocytes in sinus histocytosis indicating the proliferating cells and activated histocytes. Most of the low grade non-Hodgkin lymphomas (83.66%) showed weak (Grade I) positivity for transferrin receptors. Intermediate grade lymphomas showed moderate (Grade II) to high intensity (Grade III) for transferrin receptors (57.14% and 42.85%) respectively. Seventy five percent of high grade lymphomas showed strong (Grade III) positivity. All the 9 cases of Hodgkin lymphoma (100%) showed grade III positivity. Proportion of the cells within a tumour expressing transferrin receptors in high density are therefore likely to represent the growth fraction of the tumour.

Isolation of fetal nucleated red blood cell from maternal blood using immunomagnetic beads for prenatal diagnosis.

The immunomagnetic beads method for isolation of fetal nucleated red blood cells (FNRBCs) from peripheral blood of 78 pregnant women for prenatal diagnosis was developed. The study subjects were classified into 8-10 and 11-14 weeks of gestation (n = 39 each). Peripheral blood cells were divided into two for the FNRBCs isolation using two protocols, one with anti-CD45 depletion followed by anti-CD71 and anti-GPA monoclonal antibodies and another without CD45 depletion. The use of CD45 depletion gave a slightly higher number of sorted cells but not significantly different (p > 0.05). The percentage of CD71+ and GPA+ cells obtained from 8-10 weeks and 11-14 weeks of gestation was not different (p > 0.05). The sensitivity in determining the sorted FNRBCs for male fetal sex by PCR using 8-10 and 11-14 weeks of gestation was generally 50 and 69%, respectively. The method so developed is simple and cost effective and may thus be applied for prenatal diagnosis.

The cellular mechanisms of body iron homeostasis

Cells tightly regulate iron levels through the activity of iron regulatory proteins (IRPs) that bind to RNA motifs called iron responsive elements (IREs). When cells become iron-depleted, IRPs bind to IREs present in the mRNAs of ferritin and the transferrin receptor, resulting in diminished translation of the ferritin mRNA and increased translation of the transferrin receptor mRNA. Similarly, body iron homeostasis is maintained through the control of intestinal iron absorption. Intestinal epithelia cells sense body iron through the basolateral endocytosis of plasma transferrin. Transferrin endocytosis results in enterocytes whose iron content will depend on the iron saturation of plasma transferrin. Cell iron levels, in turn, inversely correlate with intestinal iron absorption. In this study, we examined the relationship between the regulation of intestinal iron absorption and the regulation of intracellular iron levels by Caco-2 cells. We asserted that IRP activity closely correlates with apical iron uptake and transepithelial iron transport. Moreover, overexpression of IRE resulted in a very low labile or reactive iron pool and increased apical to basolateral iron flux. These results show that iron absorption is primarily regulated by the size of the labile iron pool, which in turn is regulated by the IRE/IRP system.

Effects of the chronic malnutrition on the transferrin receptors in patients with nutritional anemia

Se ha postulado que el aporte de hierro a las células usuarias se halla bajo un control dependiente del tamaño de la fracción intracelular libre del metal, cuyos cambios se reflejarían en mensajes a la expresión de los receptores séricos o de membrana para ajustar la oferta a la demanda. La posibilidad de que los receptores de membrana pudieran estar afectados por la malnutrición calórico-proteica se exploró en estudios a través de los cambios de la capacidad de los reticulocitos circulantes de ratón normal para incorporar hierro in vitor, observando el diferente comportamiento ocasionado por la incubación de las células con suero humano de dadores normales y de pacientes de anemia nutricional. Los resultados muestran una significativa caída de dicha capacidad cuando se utilizó suero de pacientes afectados de anemia nutricional. Se discute el probable mecanismo responsable de dicha diferencia.