Rajiv Saxena

By Sreoshi Chatterjee and Rajiv K. Saxena

We have developed a new double in vivo biotinylation (DIB) technique that may be used for assessing turnover patterns of erythrocytes in circulation. This technique involves two successive in vivo biotinylation steps, interspersed by a period of 5–30 days, which would enable us to tag with biotin a population of erythrocytes entering blood circulation over a defined period of time, between the two biotinylation steps. As such we can track the age-related changes in a lifetime of the circulating erythrocytes, or we can simultaneously study two defined age cohorts of aged as well as young erythrocytes in circulation. We have extensively used this technique to look at erythrocyte loss in mouse models of anemia induced by (a) heavy metal cadmium (Cd), (b) herbicide Paraquat (PQ), (c) carbon nanotubes (CNTs), and (d) autoantibody in autoimmune hemolytic anemia (AIHA). We have found that the pattern of erythrocyte removal is distinctly different in different models of murine anemia. In certain types of anemia (CNT and AIHA), younger erythrocytes in blood circulation are preferentially removed, whereas in other cases (Cd and PQ), old erythrocytes are specifically eliminated.

Part of the book: Transfusion Medicine and Scientific Developments

By Anwar Alam and Rajiv K Saxena

The increased use of nanomaterials for biomedical purposes has warranted the need to introspect their toxicological properties and assess their utility to human health, particularly the immune system. Natural killer (NK) cells hold a pivotal position in innate immunity and serve as first line of defense against foreign bodies. Acid functionalized Carbon nanotubes (CNTs) that easily polydisperse in aqueous solution and could be coupled with fluorescent molecules were used to study the effect of carbon nanoparticles on NK cells in vitro and in vivo. Flow cytometry-based assays were used to study the effect of CNTs on various physiological parameters of NK cells, such as cell recovery, apoptosis, cell cycle, and generation of reactive oxygen species. A downregulation of the cytotoxicity of IL-2-activated murine NK cells was observed in the presence of acid-functionalized CNTs. The mechanistic basis of this downregulation was studied by assessing markers of NK cell activation (CD69), generation (NLK1.1), degranulation (CD107a) and apoptosis (annexin V assay). This chapter provides a blueprint for assessing the effect of carbon nanoparticles on NK cells. The assays mentioned in this chapter can be extrapolated to study the effect of other nanoparticles on different cell types as well.

Part of the book: Natural Killer Cells