Journal Article•
Metal Cation Requirements for Phytohemagglutinin-Induced Transformation of Human Peripheral Blood Lymphocytes
01 Mar 1970-Journal of Immunology (American Association of Immunologists)-Vol. 104, Iss: 3, pp 698-703
TL;DR: Zinc and iron appear likely to be essential for PHA-induced lymphocyte transformation in vitro, and several other metal cations were effective in reversing EDTA inhibition of P HA-induced transformation.
Abstract: Citrate and disodium EDTA were effective inhibitors of PHA-induced lymphocyte transformation. A high concentration of citrate (24 mM) was required. Citrate inhibition was totally reversible by calcium and half as effectively by magnesium. In experiments in calcium-magnesium-free medium, calcium was determined to be five times as effective as magnesium in promoting transformation. EDTA was effective in low concentrations (1.6 mM) in blocking transformation. This effect was not entirely reversible by calcium, and was not detectably affected by magnesium. Several other metal cations were effective in reversing EDTA inhibition of PHA-induced transformation. Zinc and iron appear likely to be essential for PHA-induced lymphocyte transformation in vitro .
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TL;DR: These data provide the first demonstration in vivo thatactivation of a protein phosphatase can inactivate I kappa B, and suggest one possible explanation for mechanism‐based toxicities associated with FK‐506 and CsA by demonstrating that these drugs can inhibit the calcineurin‐dependent activation of a virtually ubiquitous transcription factor.
Abstract: The interleukin-2 (IL-2) promoter consists of several independent T cell receptor (TcR) responsive elements. The induction of promoters dependent on these elements is inhibitable by the immunosuppressants cyclosporin A (CsA) and tacrolimus (FK-506). Calcineurin, a Ca2+/calmodulin-dependent protein phosphatase, is the FK-506- and CsA-sensitive enzyme required for TcR mediated activation of the IL-2 promoter. We report that a constitutively active form of calcineurin partially substitutes for the Ca2+ co-stimulus required to activate the IL-2 promoter elements IL-2A (which binds the factors OAP and Oct-1) and IL-2E (which binds NF-AT), and completely substitutes for the Ca2+ co-stimulus required to stimulate an NF-kappa B-dependent element. Calcineurin stimulates the NF-kappa B element by enhancing inactivation of I kappa B/MAD3, an inhibitor of NF-kappa B, thereby increasing the amount of nuclear NF-kappa B DNA binding activity. These data provide the first demonstration in vivo that activation of a protein phosphatase can inactivate I kappa B, and suggest one possible explanation for mechanism-based toxicities associated with FK-506 and CsA by demonstrating that these drugs can inhibit the calcineurin-dependent activation of a virtually ubiquitous transcription factor.
329 citations
Cites background from "Metal Cation Requirements for Phyto..."
...The importance of Ca2+ in TcR signal transduction can be demonstrated by the fact that removal of extracellular Ca2+ can block T cell activation (Alford, 1970)....
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TL;DR: The binding of concanavalin A to T but not B mouse spleen lymphocytes increases Ca2+ uptake in these cells which is measurable by 45 s and complete by 1 min.
Abstract: The binding of concanavalin A to T but not B mouse spleen lymphocytes increases Ca2+ uptake in these cells which is measurable by 45 s and complete by 1 min. Dibutyryl cyclic AMP, but not sodium azide inhibits induced Ca2+ uptake, whereas dibutyryl cyclic GMP enhances it. B cell mitogens do not cause a similar Ca2+ uptake in mouse B lymphocytes. The induction of increased Ca2+ uptake by T cells is discussed in terms of gated membrane channels for Ca2+.
255 citations
TL;DR: There is evidence for a primary role for Ca2+.
Abstract: TRANSFORMATION of lymphocytes by antigens and by nonspecific mitogens (lectins and anti-immunoglobulin sera) is a consequence of the binding of the mitogen to specific receptors on the cell surface1–3 The receptors rapidly form clusters (‘patches’) which may aggregate into polar ‘caps’4 at higher mitogen concentration These events initiate a series of biochemical changes—enhanced uptake of ions and metabolites1, increased cyclic GMP5, and increased metabolism of phosphatidyl inositol and other phospholipids (ref 6 and V C M, M J Hayman and M J C, unpublished)—which culminate in DNA synthesis and mitosis 48–72 h later Although the sequence, relative importance and control of these events is not yet defined, there is evidence for a primary role for Ca2+ Phaseolus vulgaris phytohaemagglutinin (PHA) initiates a slow accumulation of Ca2+ by lymphocytes7,8 and its stimulation of DNA synthesis is inhibited by citrate9, EDTA (ref 9) or EGTA (ref 10) The inhibition is reversed by Ca2+ It has also been shown that inhibition by the low concentrations (14 mM) of EGTA used did not prevent binding of PHA (ref 11) Although these results showed Ca2+ to be an important factor in initiation of transformation it was not clear whether influx of Ca2+ was the only or even the main consequence of the binding of PHA
251 citations
TL;DR: A review of the present state of knowledge on cyclosporin A is warranted because the drug has already been admirably analyzed in these reviews, but much relevant information on it has accumulated since then.
Abstract: Very little new happened in the field of immunosuppression after the discovery of azathioprine in the early 'sixties (Schwarz et al. 1959). Admittedly, there has been the introduction of heterologous antilymphocyte serum (Starzl et al. 1967), which to some extent has become a part of the regular therapeutic regimen in organ transplantation. Other than that, very little that could stop an immune response has been brought forward by the immunologists during these two past decades. Nevertheless, the understanding of immune functions has advanced a great deal during that same period, although in terms of immunosuppression the transplant surgeons were left with the old, but not so effective combination of steroids, azathoprine and somewhat later anti-lymphocyte serum (that, indeed, they still use). But a new drug is rapidly invading the market. That is cyclosporin A (CyA), which is the scope of this review. Although it was detected nearly 10 years ago (Borel 1976), it is still new as it is presently being scrutinized in clinical trials in man and is thus not commonly in use yet. In most countries it has as yet only been used for very limited purposes. The attraction of this compound is multifold, but one feature is that, unlike all other immunosuppressants, tentative mechanisms of action for it have been brought forward based on interpretable experimental data. This is, we think, why a review of the present state of knowledge on cyclosporin A is warranted. The drug has already been admirably analyzed in these reviews (Calne 1979), but much relevant information on it has accumulated since then.
192 citations
TL;DR: This chapter focuses on demonstrating the overall resemblance of the release of mediators by immunologically induced noncytotoxic reactions to secretory processes, in general.
Abstract: Publisher Summary This chapter describes the noncytotoxic release of mediators from cells induced in vitro by immunological stimuli. It discusses the release of mediators from these same cells by nonimmunological means. It focuses on demonstrating the overall resemblance of the release of mediators by immunologically induced noncytotoxic reactions to secretory processes, in general. The chapter describes the chemotaxis and phagocytosis by polymorphonuclear leukocytes; release of lysosomal enzymes from the latter cells by staphylococcal toxin; leukocidin; aggregation of platelets; and the specifically and nonspecifically induced transformation of lymphocytes. In the context of this chapter, the term “mediators” is restricted to substances whose release is directly or indirectly initiated by an immunological reaction and are responsible for one or more of the manifestations of the subsequent allergic response.
174 citations