Chrono- and Immunocorrection of Inflammatory Disorders of Internal Reproductive Organs in Women of Reproductive Age.

We compared the effectiveness of immunomodulators used in the treatment of patients with chronic salpingitis and oophoritis with or without changes in succinate dehydrogenase (SDH) activity in blood lymphocytes at incubation with the drug. Diurnal variations in individual reaction of SDH in blood lymphocytes to thymalin or ridostin were revealed. In the groups of women receiving ridostin or thymalin during the reaction of lymphocyte SDH to it, improvement of clinical laboratory and immunological parameters was observed in the majority of the patients and no effect was found in a lesser group of patients than in the groups treated with drugs during the absence of lymphocyte SDH reaction thereto. The timing of the presence of SDH reaction to drugs in the immunocompetent cells makes it possible to set the optimal daily regime of their application and to select a drug that would be most effective in each particular case.

Enhancement of natural killer cell activity in vitro against human tumor cells by some plants from Jordan.

The effect of different concentrations (0, 0.01, 0.1, and 0.5 mg/ml) of plant aqueous extracts on the anti-tumor activity of natural killer (NK) cells isolated from human blood was examined. Plant extracts induced significant enhancement of (26.6-67.7%) of NK cell activity against K562 tumor cells. This increase in NK cell cytotoxicity was found to be due to the enhancement of NK cell production of interferon-gamma (87-337%), and on tumor necrosis factor-alpha (60-200%). Furthermore, the release of both granzyme A and N-acetyl-beta-D-glucosaminidase was increased significantly when compared with controls. Activation of granzyme A and N-acetyl-beta-D-glucosaminidase was clearly observed ranging from 24.2-106.4% to 26.8-110.7%, respectively. Lastly, in the absence of IL-2, plant extracts caused a significant increase in NK-cell-induced cytotoxicity (256%) against K562 tumor cells, and in the presence of IL-2 stimulated cells plant extracts caused an increase in NK cell-cytotoxicity (112%).

Natural killer cell-dendritic cell crosstalk in the initiation of immune responses.

Dendritic cells (DCs) and natural killer (NK) cells play a critical role in early defences against cancer and infections. They specialise in complementary functions, including IL-12 or IFN-alpha/beta secretion and antigen presentation for the former, and IFN-gamma secretion and killing of infected or tumour cells for the latter. Both DCs and NK cells are also sensors of the immune system that have developed different, but partially overlapping, systems to identify pathology associated danger signals. Evidence of NK-DC interaction has accumulated recently. This interaction may lead to NK cell activation, DC activation, or apoptosis depending on the activation status of both cell types. Thus, the outcome of NK-DC crosstalk is likely to influence both innate and adaptive immune responses. This review addresses the molecular mechanisms under-lying the different NK-DC interactions, and their in vivo significance in anti-tumour or antimicrobial immunity. Finally, we discuss the potential clinical implications of this new field.

Interleukin-2-induced survival of natural killer (NK) cells involving phosphatidylinositol-3 kinase-dependent reduction of ceramide through acid sphingomyelinase, sphingomyelin synthase, and glucosylceramide synthase.

Interleukin 2 (IL-2) rescued human natural killer (NK) KHYG-1 cells from apoptosis along with a reduction of ceramide. Conversely, an increase of ceramide inhibited IL-2-rescued survival. IL-2 deprivation-induced activation of acid sphingomyelinase (SMase) and inhibition of glucosylceramide synthase (GCS) and sphingomyelin synthase (SMS) were normalized by IL-2 supplementation. A phosphatidyl inositol-3 (PI-3) kinase inhibitor, LY294002, inhibited IL-2-rescued survival, but a mitogen-activated protein kinase inhibitor, PD98059, and an inhibitor of Janus tyrosine kinase/signal transducer and activator of transcription pathway, AG490, did not. LY294002 inhibited IL-2-induced reduction of ceramide through activation of acid SMase and inhibition of GCS and SMS, suggesting the positive involvement of PI-3 kinase in ceramide reduction through enzymatic regulation. Indeed, a constitutively active PI-3 kinase enhanced growth rate and ceramide reduction through inhibition of acid SMase and activation of GCS and SMS. Further, LY294002 inhibited IL-2-induced changes of transcriptional level as well as mRNA and protein levels in acid SMase and GCS but did not affect the stability of the mRNAs. These results suggest that PI-3 kinase-dependent reduction of ceramide through regulation of acid SMase, GCS, and SMS plays a role in IL-2-rescued survival of NK cells.

Activating and inhibitory Ly49 receptors modulate NK cell chemotaxis to CXC chemokine ligand (CXCL) 10 and CXCL12.

NK cells can migrate into sites of inflammatory responses or malignancies in response to chemokines. Target killing by rodent NK cells is restricted by opposing signals from inhibitory and activating Ly49 receptors. The rat NK leukemic cell line RNK16 constitutively expresses functional receptors for the inflammatory chemokine CXC chemokine ligand (CXCL)10 (CXCR3) and the homeostatic chemokine CXCL12 (CXCR4). RNK-16 cells transfected with either the activating Ly49D receptor or the inhibitory Ly49A receptor were used to examine the effects of NK receptor ligation on CXCL10- and CXCL12-mediated chemotaxis. Ligation of Ly49A, either with Abs or its MHC class I ligand H2-D(d), led to a decrease in chemotactic responses to either CXCL10 or CXCL12. In contrast, Ly49D ligation with Abs or H2-D(d) led to an increase in migration toward CXCL10, but a decrease in chemotaxis toward CXCL12. Ly49-dependent effects on RNK-16 chemotaxis were not the result of surface modulation of CXCR3 or CXCR4 as demonstrated by flow cytometry. A mutation of the Src homology phosphatase-1 binding motif in Ly49A completely abrogated Ly49-dependent effects on both CXCL10 and CXCL12 chemotaxis, suggesting a role for Src homology phosphatase-1 in Ly49A/chemokine receptor cross-talk. Ly49D-transfected cells were pretreated with the Syk kinase inhibitor Piceatannol before ligation, which abrogated the previously observed changes in migration toward CXCL10 and CXCL12. Piceatannol also abrogated Ly49A-dependent inhibition of chemotaxis toward CXCL10, but not CXCL12. Collectively, these data suggest that Ly49 receptors can influence NK cell chemotaxis within sites of inflammation or tumor growth upon interaction with target cells.

Src homology region 2-containing protein tyrosine phosphatase-2 (SHP-2) can play a direct role in the inhibitory function of killer cell Ig-like receptors in human NK cells.

The inhibitory forms of killer cell Ig-like receptors (KIR) are MHC class I-binding receptors that are expressed by human NK cells and prevent their attack of normal cells. Substantial evidence indicates that the mechanism of KIR-mediated inhibition involves recruitment of the protein tyrosine phosphatase, Src homology region 2-containing protein tyrosine phosphatase (SHP)-1, to phosphorylated immunoreceptor tyrosine-based inhibitory motifs (ITIMs). However, the functional significance of parallel recruitment of a SHP-1-related phosphatase, SHP-2, to KIR ITIMs has not been addressed. In the present study, our results with mutant forms of a classical KIR, KIR3DL1, show a direct correlation between SHP-2 recruitment and functional inhibition of target cell conjugation and cytotoxicity. In addition, KIR3DL1 inhibition of target cell cytotoxicity is blocked by overexpression of a dominant-negative form of SHP-2. Finally, KIR3DL1 fused directly with the catalytic domain of SHP-2 inhibits both target cell conjugation and cytotoxicity responses. These results strongly indicate that SHP-2 catalytic activity plays a direct role in inhibitory KIR functions, and SHP-2 inhibits NK cell activation in concert with SHP-1.

Human NK cells express endothelial nitric oxide synthase, and nitric oxide protects them from activation-induced cell death by regulating expression of TNF-alpha.

Although NO appears important in rodent immune responses, its involvement in the human immune system is unclear. We report that human NK cells express constitutive endothelial NO synthase mRNA and protein, but not detectable levels of inducible NO synthase. They produce NO following activation by coculture with target cells or cross-linking with anti-CD16 mAb, and production is increased in the presence of IL-2. N-monomethyl-L-arginine (L-NMA), a NOS inhibitor, partially inhibited NK cell lysis of four different target cells (<40% inhibition at 500 microM L-NMA), but not granule release following coculture with target cells, or Fas ligand induction following cross-linking with anti-CD16 mAb. However, L-NMA augmented apoptosis of NK cells induced by activation through CD16 ligation or coculture with K562. An NO donor, S-nitroso-N-acetylpenicillamine (SNAP), suppressed apoptosis of NK cells induced by CD16 cross-linking or coculture with target cells, suggesting that endogenous NO production is involved in protection of NK cells from activation-induced apoptosis, thereby maintaining NK activity. SNAP also suppressed, and L-NMA enhanced, expression of TNF-alpha, reported to be involved in activation-induced NK cell death, in response to CD16 cross-linking. Suppression of anti-CD16-induced apoptosis by SNAP was reversed by the addition of rTNF-alpha. DNA-binding activity of the transcription factor, NF-AT, which is involved in TNF-alpha induction upon ligation of CD16, was inhibited by SNAP and enhanced by L-NMA. Our results suggest that down-regulation of TNF-alpha expression, possibly due to suppression of NF-AT activation, is a mechanism by which endogenous NO protects NK cells from activation-induced apoptosis, and maintains lytic capacity.

Enhancement of natural killer cell activity and T and B cell function by buffered vitamin C in patients exposed to toxic chemicals: the role of protein kinase-C.

After exposure to many toxic chemicals, NK function can be decreased significantly. Weeks or months later, natural killer (NK) function can rebound to normal levels in some and can be suppressed for prolonged periods of time in other patients. In view of this, we decided to study the effect of buffered vitamin C on NK, T and B cell function in patients who had been exposed to toxic chemicals. After the first blood draw, 55 patients immediately ingested granulated buffered vitamin C in water at a dosage of 60 mg/Kg body weight. Exactly 24 hours later, blood was again drawn for a follow-up study of NK, T and B cell function. Vitamin C in high oral dose was capable of enhancing NK activity up to ten-fold in 78% of patients. Lymphocyte blastogenic responses to T and B cell mitogens were restored to the normal level after vitamin C usage. Signal transduction enzyme protein kinase C (PKC) appeared to be involved in the mechanism of induction of NK activity by vitamin C. We conclude that immune functional abnormalities can be restored after toxic chemical exposure by oral usage of vitamin C.