Effect of avitaminosis B6 in mice on T-lymphocyte function in vitro

The effect of different degrees of avitaminosis B₆ in mice on the cytolytic activity of T lymphocytes, measured as the quantity of Na₂Cr⁵¹O₄ released from lysed target cells, was studied on a model of the primary immune response in a mixed lymphocyte culture in vitro. Keeping animals for 3 weeks on a diet without pyridoxine did not affect the ability of the lymphocytes to proliferate in vitro or their cytolytic activity. In animals receiving a diet without pyridoxine for 45 days the content of pyridoxal-5-phosphate in the spleen was 55% lower than in the control. Lymphocytes taken from these animals, when cultured in vitro, showed sharply weakened ability to incorporate [³H]thymidine into DNA in response to the alloantigen. The cytolytic activity of these lymphocytes also was reduced. The ability of different forms of pyridoxine to restore the functions of T lymphocytes, when disturbed by avitaminosis B₆, was studied.Laboratory of Systemic Blood Diseases, Oncologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Kraevskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 8, pp. 185–188, August, 1977.     

Fas (CD95/Apo-1) ligand regulation in T cell homeostasis, cell-mediated cytotoxicity and immune pathology

Members of the tumor necrosis factor (TNF) superfamily are crucially involved in the regulation of T cell activation, homeostasis and cytotoxicity. In particular, Fas ligand (FasL), expressed by activated T lymphocytes, induces cell-mediated cytotoxicity and may also be responsible for apoptotic suicide. Tight regulation of this death-inducing ligand is a prerequisite for proper immune defense and homeostasis. In this review, we will discuss various aspects of FasL regulation in cell-mediated cytotoxicity, immune homeostasis and the immunopathology of diseases.     

Nociceptive muscle reflex responses in human forearms

In healthy volunteers, 5-min noxious stimulation with rectangular electrical pulses applied transcutaneously to the phalanges enhanced tonic activity in the palmar and finger flexor muscles resulting in a specific electromyographic pattern consisting of two successive bursts of activity which appeared after a period of inhibition. In patients with chronic pain in the arm, significantly lower thresholds for the first and the second waves of reflex activity have been found. This electromyographic pattern of the forearm muscle reflex responses is supposed to be similar to the nociceptive flexor reflex in the leg. It can be useful for objective assessment of the effectiveness of analgesia and pain syndrome therapy in patients with cervical spinal cord injury. Translated fromByulleten' Eksperimental'noi Biologii I Meditsiny, Vol. 126, No. 9, pp. 278–282, September, 1998     

Investigation of the morphology of cell clones, derived from the mammalian EBTr cell line and their susceptibility to vaccine avian poxvirus strains FK and Dessau

The ability for replication of vaccine avian pox viral strains FK and Dessau in cell clones, derived from the EBTr cell line, derived from embryonic bovine trachea, was studied. The derived seven cell clones showed different morphological characteristics and diverse sensitivity to both vaccine avian pox viral strains. Hence, the EBTr-derived cell clones could be used for cultivation, as well as for differentiation of vaccine avian pox viral strains. In addition, studies have been undertaken to elucidate the possible use of cultivated strains in these heterologous cell culture system's vaccine avian pox viral strains for biotechnology, as well as for solving problems, related to infection of people with avian viruses.     

Trypanosoma cruzi histone H1 is phosphorylated in a typical cyclin dependent kinase site accordingly to the cell cycle

Histone H1 of most eukaryotes is phosphorylated during the cell cycle progression and seems to play a role in the regulation of chromatin structure, affecting replication and chromosome condensation. In trypanosomatids, histone H1 lacks the globular domain and is shorter when compared with the histone of other eukaryotes. We have previously shown that in Trypanosoma cruzi, the agent of Chagas' disease, histone H1 is phosphorylated and this increases its dissociation from chromatin. Here, we demonstrate using mass spectrometry analysis that T. cruzi histone H1 is only phosphorylated at the serine 12 in the sequence SPKK, a typical cyclin-dependent kinase site. We also found a correlation between the phosphorylation state of histone H1 and the cell cycle. Hydroxyurea and lactacystin, which, respectively, arrest parasites at the G1/S and G2/M stages of the cell cycle, increased the level of histone H1 phosphorylation. Cyclin-dependent kinase-related enzymes TzCRK3, and less intensely the TzCRK1 were able to phosphorylate histone H1 in vitro. Histone H1 dephosphorylation was prevented by treating the parasites with okadaic acid but not with calyculin A. These findings suggest that T. cruzi histone H1 phosphorylation is promoted by cyclin dependent kinases, present during S through G2 phase of the cell cycle, and its dephosphorylation is promoted by specific phosphatases.     

Natural killer cell differentiation: insights from knockout and transgenic mouse models and in vitro systems

Summary: In the last few years, the routine development of knockout and transgenic mice and the ease with which rare progenitor populations can be isolated from hematopoietic organs and cultured in vitro has facilitated significant advances in understanding the lineage and development of natural killer (NK) cells. Fluorescence-activated cell sorter analyses have identified a common lymphoid progenitor capable of giving rise to NK, T, and B cells, confirming the lymphoid origin of NK cells. Knockout and transgenic mouse models have pointed to an absolutely critical role for signals sent through the interleukin (IL)-2/lS receptor β (CD 122) chain and common γ (γc) chain for NK development. Such signals are likely relayed inside the cell by the tyrosine kinase Jak3, which associates with γc. Recently developed IL-15 and IL-15 receptor a knockout mice have pinpointed IL-15 as the mediator of this signal. Other mouse models have indicated an unexpected role for flt3 ligand in early NK-cell development as well as minor roles for stem cell factor and IL-7 in expanding NK-cell progenitor numbers. Finally, in vitro culture systems have proven useful in identifying the point in NK development at which each of these signals is critical.