Bioluminescent assay for human lymphocyte blast transformation.

One of the basic tests of in vitro evaluation of immune cell functional activity is a proliferative response of lymphocytes on the action of external stimuli such as mitogenic lectines, antigens, etc. We compared two methods used to assess the lymphocyte functional status. (1) [3H]thymidine incorporation and (2) bioluminescence for determination of intracellular ATP in blast cells. Comparison has been done for healthy donors and patients with proven low immunological status. The proposed bioluminescent method for evaluation of the proliferative response was shown to be sensitive enough for diagnostic purposes. This method allows one to process a large number of samples at the same time and correlates highly with the radionuclide test use hazardous radioactive materials.

The resistance of activated T-cells from SLE patients to apoptosis induced by human thymic stromal cells.

In this paper we show the differential sensitivity of phytohemagglutinine (PHA) activated T-cells from healthy donors or patients with systemic lupus erythematosus (SLE) to apoptosis induced by human thymic stromal cell line of epithelial origin. T-cells from SLE patients were mainly resistant to the apoptotic action of the stromal cells, while normal T-lymphocytes readily died via apoptosis. Gel electrophoresis revealed a DNA fragmentation pattern characteristic of apoptosis after 18 h of coculture. The simultaneous measurement of [3H]-thymidine uptake showed that the proliferative response of T-cells from SLE patients was significantly decreased compared to their normal counterparts. Such difference may account for the distinct result of interactions between the stromal and lymphoid cells, leading to the subsequent survival of T-lymphocytes from SLE patients. Nevertheless pretreatment of normal activated T-lymphocytes with anti-Fas mAbs, which have the capacity to substantially inhibit signaling through this receptor resulted in abolition of this form of programmed cell death. Thus, the precise role of Fas receptor and its ligand in this in vitro test system needs further investigation.

[Protein phosphatases: structure and function]. / Proteinfosfatazy: struktura i funktsii.

The process of protein and enzyme systems phosphorylation is necessary for cell growth, differentiation and preparation for division and mitosis. The conformation changes of protein as a result of phosphorylation lead to increased enzyme activity and enhanced affinity to substrates. A large group of enzymes--protein kinases--is responsible for phosphorylation process in cell, which are divided into tyrosine- and serine-threonine-kinases depending on their ability to phosphorylate appropriate amino acid residues. In this review has been considered the functional importance and structure of protein phosphatases--enzymes, which are functional antagonists of protein kinases.

[Tyrosine protein kinase: role in the process of activating lymphocytes]. / Tirozinovye proteinkinazy: rol' v protsesse aktivatsii limfotsitov.

Some types of receptor and intracellular protein-tyrosine kinases are reviewed. These enzyme systems play an important role in activation of T- and B-lymphocytes and their precursors. The relationship is shown between the two main ways of lymphocyte activation: the phosphatidylinositol metabolic pathway, induced by protein kinase C, and the protein-tyrosine kinase pathway of intracellular protein and enzyme phosphorylation.

[Apoptosis and thymocyte development (epithelial cells as inducers of thymocyte apoptosis)]. / Apoptoz i razvitie timotsitov (épitelial'nye kletki kak induktory apoptoza timotsitov).

Apoptosis, together with proliferation, is a main factor of selection of the clones of developing T-lymphocytes: the clones not supported by positive selection are subject to apoptosis and apoptosis accounts for discarding of potentially autoaggressive clones, i.e., for negative selection in the thymus and peripheral lymphoid tissue. Realization of apoptosis at different stages of the development of T-lymphocytes depends to a varying extent on Fas, Bcl-2, p53, and other regulators. The dendritic cells are the main cell type, the contact with determines apoptosis of T-lymphocytes. A possible role of the epithelial cells was shown in few models (on murine cells) and was not practically studied. We obtained a line of epithelial cells of the human thymus cells HTSC, cocultivation with which induces apoptosis of immature thymocytes and blood T-cells activated by mitogens. Development of apoptosis is suppressed by inhibitors of protein and RNA synthesis, chelators Ca2+, ions Zn2+, and factors destroying the cytoskeleton components. In this model, interaction of pairs of molecules CD4-HLA class II and LFA-1-ICAM-1. When in contact with the HTSC cells, the thymocytes of mice mutant for Fas-receptor (line MRL.lpr) are subject to apoptosis, but when this receptor is present, it affects the development of apoptosis.

Expression of protooncogenes during lymphocyte activation by growth factors.

Effects of growth factors of non-immune origin including somatotropin (ST) and platelet-derived growth factor (PDGF) on the expression of the proteins encoded by c-fos, c-myc, c-fun, and c-ets family protooncogenes were studied for the first time. The dynamics of the oncoprotein expression in activated CD(3+)-lymphocytes was investigated by immunoblotting. The accumulation of the Fos and Myc proteins was enhanced in T-lymphocytes treated with ST, PDGF, or phytohemagglutinin; the accumulation was maximum at 30-60 min and decreased in 2 h; the data indicate that the oncoproteins participate in the early lymphocyte activation by various growth factors. The Jun protein appears only in 3 h after the onset of lymphocyte activation; this suggests independent participation of Fos in the early stages of lymphocyte activation prior to the appearance of Jun, preceding the joint action of Fos and Jun within the AP-1 transcription complex. The products of the c-ets family are differentially activated by the studied growth factors. Resting lymphocytes actively accumulate the Ets-1 protein; ST and PDGF activation decreases Ets-1 expression in 2 h. The Ets-2 protein is not detected in resting cells and PDGF-activated lymphocytes, whereas lymphocyte activation by ST is associated with accumulation of Ets-2. The data suggest that the product of the c-ets-1 gene is more important in the regulation of resting cells and the product of the c-ets-2 gene is important during activation of lymphocytes by ST. The results indicate that activation of lymphocytes with growth factors of non-immune origin is mediated by several signal transduction pathways.