Mammalian teeth develop during embryogenesis as epithelio-mesenchymal organs. The primary enamel knot is considered as a signaling center in tooth morphogenesis. After tooth bell formation, this epithelial structure undergoes apoptosis. Activation of caspase 3 represents a crucial step in the intracellular death machinery. Procaspase 3 and caspase 3 molecules were localized in the primary enamel knot of the field vole using immunohistochemistry. Different fixation procedures in cryopreserved and paraffin-embedded tissues and detection systems based on peroxidase and alkaline phosphatase mediated color reactions were applied. Apoptosis was detected using morphological criteria and the TUNEL assay. Procaspase 3 was found in both the epithelial and mesenchymal part of the tooth germ. Active caspase 3 was localized particularly in the primary enamel knot, its distribution correlated with dental apoptosis and showed a similar pattern in the field vole as in the mouse.
The aim was to study the role of major histocompatibility complex (MHC), in mice named H-2, during early allogeneic reactions (AR) of brain cortex cells or lymphocytes. We used neuronal and glial enriched perikarya, spleen and thymus lymphocytes or their subpopulations. Rat AR was also assayed between C-6 astrocytoma cells and spleen lymphocytes. We demonstrated that: 1) H-2 dependent stimulation of Na+,K+-ATPase and ouabain- sensitive K+-dependent p-nitrophenylphosphatase (K+-pNPPase) activities represented specific response in both AR of unseparated brain cells or lymphocytes. On the other hand, non-specific AR-induced stimulation of Ca2 + - ATPase activity was observed. 2) Allogeneic enriched glial fractions reacted similarly by the same enzyme activation in contrast to no change in AR between enriched neuronal fractions. Allorecognition ability of glial cells was confirmed by AR between C-6 astrocytoma cells and lymphocytes. 3) Mature thymus lymphocytes exerted alloreactivity by specific activation of Na+,K+-ATPase or K+-pNPPase, in contrast to no change in AR between immature lymphocyte subpopulations. 4) MHC Class II monoclonal antibody inhibited Na+,K+-ATPase and K+-pNPPase activities in brain cells as well as in thymus and spleen lymphocytes in a dose-dependent manner. Results support former studies about alloantigen-induced uncoupling in brain oxidative cortex metabolism (Kovářů Med. Biol. 58: 273, 1980) via Na+,K+-ATPase and K+-pNPPase inhibition by mechanism which can mimic MHC restriction.
This study describes the effects of cytokine peptides released into the supernatant during an early allogeneic reaction (AR) of mouse spleen lymphocytes or brain cortex cells which differ in their major histocompatibility complex (MHC). The peptides were isolated by ultrafiltration, liquid chromatography and HPLC. We found that both peptides stimulated the cell surface Na+,K+-ATPase and Ca2+-ATPase activities of quiescent spleen lymphocytes in vitro and mimicked early allogeneic cell interactions. Both brain and spleen AR peptides inhibited Concanavalin A-stimulated spleen lymphocyte proliferation, whereas 3H-TdR incorporation into DNA of the E7 neuroblastoma cell Une was stimulated by these peptides. The peptide isolated from the supernatant of the allogeneic brain ceU reaction inhibited phagocytosis in phorbol myristate-stimulated LA5-9/8 mouse macrophage cell line. Immunosuppressive activity of spleen AR peptide is supported by inhibition of spontaneous E rosette formation by lymphocytes. The immunosuppressive effect of isolated peptide cytokines on lectin-activated lymphocytes was comparable with the serum thymic factor (FTS, Lenfant et al. 1983). These changes demonstrate the pleiotropic cytokine actions mediated by plasma membrane of immune system and brain cells.