SIMULTANEOUS MEASUREMENT OF NUCLEATED CELL COUNTS AND CELLULAR DIFFERENTIALS IN RAT BONE MARROW EXAMINATION USING FLOW CYTOMETER

Kinetic properties of E-NTPDase activity in lymphocytes isolated from bone marrow, thymus and mesenteric lymph nodes of Wistar rats

Plasma membrane anchored nucleotidases (E-ATPDases), as the E-NTPDase family, could hydrolyze and regulate the pericellular levels of nucleotides in lymphocytes. Each immune organ has a different microenvironment and display lymphocytes with different functions and phenotypes. Considering the different functions of each resident subpopulations of lymphocytes, the E-ATPDases activities in bone marrow (BML), thymus (TL) and mesenteric lymph node (MLL) lymphocytes of Wistar rats were characterized. The hydrolysis of extracellular nucleotides (eATP and eADP) showed linearity in time of reaction between 0 and 120 min, and concentration of lymphocytes expressed in proteins between 1 and 6 μg protein in the reaction medium. The optimal activity was attained at 37 °C in a pH value of 8.0. The necessity of the cofactors Ca2+ and Mg2+ for the enzymatic activity was confirmed through a curve of concentration of 0-1000 µM in the reaction medium, with both cofactors showing similar effects in the enzymatic activity. The Chevillard plot revealed that the hydrolysis of eATP and eADP occurred at the same active site of the enzyme. The analyses of E-ATPDases inhibitor and enzyme specificity showed possible involvement of E-NTPDase isoforms - 1 and - 2 in the isolated cells. Furthermore, different kinetic behavior of the nucleotide hydrolysis in each resident subpopulation lymphocyte was observed in this study, as MLL showed the higher Vmax with the lowest km values, while TL had the lowest Vmax and high km values. The kinetic values for E-NTPDase activity of each immune tissue lymphocytes can be an important therapeutic target for numeral immune-related diseases.

Best practices for evaluation of bone marrow in nonclinical toxicity studies

This manuscript is intended to provide a best practice approach to accurately and consistently assess toxicant-induced bone marrow effects of test articles. In nonclinical toxicity studies, complete blood count data in conjunction with the histological examination of the bone marrow are recommended as the foundation for assessing the effect of test articles on the hematopoietic system. This approach alone can be used successfully in many studies. However, in some situations it may be necessary to further characterize effects on the different hematopoietic lineages, either by cytological or flow cytometric evaluation of the bone marrow. Both modalities can be used successfully, and which one is selected will depend on the expertise, preference of the facility, and the nature of the change in the bone marrow. Other specialized techniques such as clonogenic assays or electron microscopy are used rarely to further characterize hematotoxicity. The indications and techniques to successfully employ histological, cytological, or flow cytometric evaluation as well as clonogenic assays and electron microscopy are reviewed.

The role of intestinal bifidobacteria on immune system development in young rats

AIM

The effects of intestinal bifidobacteria on the development of immunity in early life were explored.

METHODS

Neonatal SD rats born and housed under strict barrier systems were fed from birth with sufficient antibiotics (bifidobacteria minimisation group) or supplemented daily with 1x10(10) colony-forming units of live Bifidobacterium longum (bifidobacteria supplementation group). Relevant indices of immune development were determined at one, three and six weeks old.

RESULTS

Compared to the control group, minimisation of the intestinal bifidobacteria delayed maturation of dendritic cells in Peyer's Patches and the development of T cells in the thymus, increased IL-4 secretion in the plasma, down-regulated IL-12, IL-10 mRNA and the interferon-gamma/IL-4 mRNA ratio in intestinal mucosa, decreased interferon-gamma mRNA in cultured peripheral blood mononuclear cells (PBMCs), and reduced immunoglobulin-M production in cultured PBMCs. Conversely, supplementation with bifidobacteria promoted dendritic cell maturation in Peyer's Patches, up-regulated IL-12, IL-10, interferon-gamma mRNA and the interferon-gamma/IL-4 ratio in intestinal mucosa, increased interferon-gamma gene expression in cultured PBMCs, and raised immunoglobulin-M secretion in cultured PBMCs.

CONCLUSIONS

Intestinal bifidobacteria could promote the maturation of dendritic cells and its expression of IL-12 locally in the gut, influence the development of T cells in the thymus, favour the development of T-helper cell type 1 response by increasing the local and systemic expression of interferon-gamma and ensure the intestinal regulatory T cell response by promoting the local expression of IL-10. In addition, they enhance antibody synthesis by PBMCs, thereby affecting the development of both the gut and systemic immunity in early life.