Enhancement of mononuclear cell oxidative burst by early post-transfer sera from human patients after unsuccessful embryo transfer

Early pregnancy sera were earlier shown to modulate T lymphocyte rosetting with sheep erythrocytes. We set out to investigate whether early pregnancysera also modulate the state of activation of another immunologically relevant cell type, the monocyte. As an index of monocyte activation, we measured phorbol ester-triggered oxidative burst activity by a highly sensitive chemiluminescence method. Contrary to our expectations, incubation of mononuclearcells with sera taken early after embryo transfer from patients with a successfully developing pregnancy had no effect. Unexpectedly, such sera from patients from a control group of patients in whom no pregnancy developed after embryo transfer caused enhancement of mononuclear cell chemiluminescence. Stimulatory activity of these sera appeared between days 4 and 6 and was maximal between days 7 and 9 post embryo transfer. Whether this phenomenon is causally related to, or represents a consequence of the failure of embryo transfer, can currently not be decide

Protein Kinase C θ Affects Ca2+ Mobilization and NFAT Activation in Primary Mouse T Cells

Protein kinase C (PKC)θ is an established component of the immunological synapse and has been implicated in the control of AP-1 and NF-κB. To study the physiological function of PKCθ, we used gene targeting to generate a PKCθ null allele in mice. Consistently, interleukin 2 production and T cell proliferative responses were strongly reduced in PKCθ-deficient T cells. Surprisingly, however, we demonstrate that after CD3/CD28 engagement, deficiency of PKCθ primarily abrogates NFAT transactivation. In contrast, NF-κB activation was only partially reduced. This NFAT transactivation defect appears to be secondary to reduced inositol 1,4,5-trisphosphate generation and intracellular Ca2+ mobilization. Our finding suggests that PKCθ plays a critical and nonredundant role in T cell receptor–induced NFAT activation

Fusion pore expansion is a slow, discontinuous, and Ca2+-dependent process regulating secretion from alveolar type II cells

In alveolar type II cells, the release of surfactant is considerably delayed after the formation of exocytotic fusion pores, suggesting that content dispersal may be limited by fusion pore diameter and subject to regulation at a postfusion level. To address this issue, we used confocal FRAP and N-(3-triethylammoniumpropyl)-4-(4-[dibutylamino]styryl) pyridinium dibromide (FM 1-43), a dye yielding intense localized fluorescence of surfactant when entering the vesicle lumen through the fusion pore (Haller, T., J. Ortmayr, F. Friedrich, H. Volkl, and P. Dietl. 1998. Proc. Natl. Acad. Sci. USA. 95:1579–1584). Thus, we have been able to monitor the dynamics of individual fusion pores up to hours in intact cells, and to calculate pore diameters using a diffusion model derived from Fick's law. After formation, fusion pores were arrested in a state impeding the release of vesicle contents, and expanded at irregular times thereafter. The expansion rate of initial pores and the probability of late expansions were increased by elevation of the cytoplasmic Ca2+ concentration. Consistently, content release correlated with the occurrence of Ca2+ oscillations in ATP-treated cells, and expanded fusion pores were detectable by EM. This study supports a new concept in exocytosis, implicating fusion pores in the regulation of content release for extended periods after initial formation

Acer Bosniacum mihi

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