Synergistic induction of interferon-γ by interleukin-2, interleukin-12 and poly(I:C) in a human natural killer cell line.

Natural killer (NK) cells express various Toll-like receptors (TLRs). Little is known about the role of TLRs in direct NK cell activation. To clarify possible synergistic roles of cytokine and TLR signaling, human NK cell line KHYG-1 was stimulated with agonists for TLR1-9. IFN-γ production was not significantly induced following stimulation with single TLR agonists. Of the nine TLR agonists tested, only poly(I:C) strongly upregulated IFN-γ production by synergistic interleukin-2 (IL-2) and IL-12 stimulation. The role of TLR3 signaling was also examined. An inhibitor of Toll-IL-1 receptor domain-containing adaptor inducing IFN-ß (TRIF) blocked this synergistic action. However, TLR3 expression was unchanged in the presence of IL-2 and IL-12. Our findings suggest a possible role for type 1 cytokines in NK cell IFN-γ production against viral infections.

Expression of inducible microsomal prostaglandin E synthase in local lesions of endometriosis patients.

PROBLEM: Recently, an inducible microsomal human prostaglandin E synthase (mPGES) was identified. This enzyme converts the cyclooxygenase (COX) product, prostaglandin (PG) H(2), to PGE(2), an eicosanoid linked to carcinogenesis. Although elevated levels of PGE(2) have been observed in many tumor types including colorectal adenomas and cancers, its role in the pathophysiology of endometriosis is unknown. We previously reported increased expression of COX-2 messenger RNA (mRNA) in local lesions of endometriosis. To further elucidate the mechanism responsible for the elevated levels of PGE(2) in endometriosis, we examined the expression levels of mPGES. METHOD OF STUDY: Samples were obtained from 28 patients, fixed in formalin, and embedded in paraffin for immunohistochemical analysis. We examined the expression of mPGES mRNA in seven cases by reverse transcriptase-polymerase chain reaction using total RNA extracted from frozen samples. RESULTS: Immunohistochemistry revealed increased mPGES immunoreactivity in endometriosis samples compared with eutopic endometria. Microsomal PGES immunoreactivity was observed in both epithelial cells and stromal or inflammatory cells of endometriosis. Increased expression of mPGES-1 mRNA was detected in most of the endometriosis samples. CONCLUSION: Our results suggest that expression of mPGES in addition to COX-2 plays a role in increasing PGE(2) production in endometriosis.

Granulocyte colony-stimulating factor suppresses autologous tumor killing activity of the peripheral blood lymphocytes in the patients with ovarian carcinoma.

PROBLEM: Granulocyte colony-stimulating factor (G-CSF) is often administered to patients with chemotherapy-induced leukocytopenia. However, adequate attention has not been paid to its effects on cancer immunology. Reported by us and others, G-CSF often induces immunosuppression and down-regulation of response T helper (Th)2 directed immune reaction both in vivo and in vitro. In this study, we analyzed the effects of G-CSF on interferon (IFN)-gamma production and autologous tumor killing (ATK) activities of peripheral blood mononuclear cells (PBMCs). METHODS OF STUDY: In order to evaluate the cytokine-induced activation of peripheral T and natural killer (NK) cells, we analyzed IFN-gamma production by interleukin (IL)-2- and IL-12-stimulated PBMCs, using the ELISPOT assay. Specific killing of autologous tumor cells was evaluated by lactate dehydrogenase (LDH) release assay. RESULTS: The PBMC collected from both cancer-bearing patients and healthy subjects showed IL-2- and/or IL-12-induced IFN-gamma production. The frequency of IFN-gamma producing cells was significantly higher in the normal subjects compared with the patients with advanced ovarian carcinoma. The ATK activity was also enhanced in IL-2- and/or IL-12-stimulated PBMCs of patients with ovarian carcinoma. G-CSF almost completely abolished IFN-gamma production and ATK activity of PBMC stimulated with IL-2 and/or IL-12. CONCLUSIONS: The G-CSF appears to be a suppressor of antitumor immunity. Routine administration of G-CSF to cancer patients may not be recommended, except for febrile neutropenia.

Granulocyte colony stimulation factor (G-CSF) suppresses interleukin (IL)-12 and/or IL-2 induced interferon (IFN)-gamma production and cytotoxicity of decidual mononuclear cells.

PROBLEM: The placenta is one of the few non-hematopoietic tissues to express granulocyte colony stimulation factor (G-CSF). Placental G-CSF production is considered to be one of the major causes of granulocytosis during pregnancy although its physiological role in pregnancy has not yet been examined. METHOD OF STUDY: The effects of G-CSF on interleukin (IL)-2 and/or IL-12 induced interferon (IFN)-gamma production of magnetic cell sorting (MACS) sorted decidual lymphocytes was examined by enzyme-linked immunosorbent spot-forming cell assay (ELISPOT). The effect of G-CSF on cytotoxicity of decidual lymphocytes against the choriocarcinoma cell line JEG-3 was examined by lactate dehydrogenase (LDH) release assay. RESULTS: As previously reported by us, IL-2 and/or IL-12 activated decidual mononuclear cells were capable of killing choriocarcinoma cells. We observed that G-CSF abolished IFN-gamma production and cytotoxicity of decidual mononuclear cells and MACS sorted CD56+ cells. CONCLUSIONS: In addition to its well-known trophic effects on hematopoiesis, our results suggest about new roles of G-CSF in reproductive immunology.