The most important progress in immunology in the last decade is the description of regulatory lymphocytes, among which Treg cells and regulatory NKT cells are much attractive to not only immunologists but also almost all biomedical researchers. Meanwhile, it is noted that NK cells are not only ＂Killers＂ but also regulate innate and adaptive immunity, especially in early stage, by secreting cytokines and cell-cell contact. In this review, we are going to briefly summarize the progresses in regulatory lymphocytes including T cells （Treg, Tr1, Th3）, NKT cells and NK cells, and then extensively introduce the positive regulatory function of NK cells in both normal immune response and in disease condition （tumor, infection and autoimmunity）, and finally, to focus on the most latest progression in the negative regulatory effects of NK cells on normal and pathogenic immune response. In conclusion, we speculate that a ＂regulatory NK （NK-reg）＂ cell subset exist and need to explore.
We have previously shown a critical role of prolactin (PRL) during maturation and anti-tumor effects of murine natural killer (NK) cells in vitro and in vivo. We extended that study by exploring the ability of human NK cell lines (NK-92 and YT cell) to express PRL receptor (PRL-R) and to respond to PRL stimulation in vitro. Both human NK cell lines constitutively expressed PRL-R on membrane and mRNA transcripts,NK-92 cells contained higher level of PRL-R than YT cells,which correlated to the enhanced capacity of the cells to proliferate and to lyse target cells in response to PRL stimulation in the presence of trace amount of IL-2 or IL-15 in vitro. Two differences between IL-2 and IL-15 in functioning on human NK cells were for the first time observed. PRL synergized with IL-15 to improve proliferation of NK cells in a dose-dependent manner without double peak manifesting like IL-2. Although PRL enhanced the cytotoxicity of IL-2 or IL- 15 activated NK cells,it exerted the function through up-regulating gene expression of perforin without influence of FasL in IL-2-stimulated NK cells,while in IL-15-stimulated NK cells,PRL did the function through up-regulating gene expression of both perforin and FasL but not IFNγ. PRL increased expressions of IL-2Rα on membrane and of IL-2 mRNA in cells,indicating that PRL up-regulated NK cell function by improving positive feedback between IL-2 and IL-2R. The similar results were also observed in network between IL-15 and IL-15R. These data indicate a potential role of PRL in human NK cell modulation.
Partial hepatectomy （PHx） in mammals is a very common experimental model to investigate the process of liver regeneration. The surgery itself could give birth to a series of stresses, such as the temporary raise of body temperature and the ischaemia-reperfusion injury. Heat shock proteins （HSPs） were a family of stress-inducible proteins involved in maintaining cell homeostasis and regulating the immune system. In our study, we intended to investigate the expression and role of HSPs in liver regeneration. Using RT-PCR and Western blotting, we determined the expression in regenerating liver of HSP27, HSP60, HSP70 and HSP90 in mRNA level and protein level, respectively, with mice treated with sham operation as controls. We also used quercertin as an inhibitior of HSPs to explore their effects on liver regeneration. We found that hepatic expression of HSPs increased at the early phase of liver regeneration and declined to the constitutively low level later. Moreover, quercetin pretreatment delayed the progress of liver regeneration in mice via inhibition of HSPs. The results indicated that HSPs played an important role in liver regeneration. Cellular ＆ Molecular Immunology. 2007;4（1）：53-57.
Type 2 cytokines are usually predominant in tumor patients and associated with tumor progression.To explore whether reversing of type 2 predominance could be a promising strategy in tumor immunotherapy,PBMCs of 35 lung cancer patients and 19 healthy subjects were prepared and subjected to be examined for cytokine secretion and gene expression.Tetra-Methylpyrazine (TTMP),extracted from a traditional Chinese medicinal herb which has been used in clinic to reverse the Th2 status of cancer patients in China,was added to PBMC culture. Determined by RT-PCR,the positive percentages of mRNA expression of type 1 cytokines (8.6% for IFN-γ and 11.4% for IL-2) were lower than those of type 2 cytokines (71.4% for IL-4,60% for IL-6 and 80% for 1L-10) in patients' PBMCs.The potential of gene expressing (measured as relative intensity to the ratio of β-actin) in the patients for type 1 cytokines was also in a low level (0.111 for IFN-γ,0.119 for IL-2) in comparison with a relative high level for type 2 cytokines (0.319 for IL-4,0.303 for IL-6 and 0.377 for IL-10).Meanwhile,both positive percentage and relative intensity of gene expression were lower for a type 1 cytokine-related transcription factor T-bet (31.4% and 0.142,respectively) than those for type 2 cytokine-related GATA3 (85.7% and 0.378, respectively).The blood serum levels of IFN-γ and IL-2 in the patients were slightly lower but not significantly when compared with healthy control.In contrast,the levels IL-4 and IL-6 in patients were significantly higher than those in healthy subjects by ELISA analysis.TTMP could enhance supernatant concentration and gene expression levels of IFN-γ,IL-2 and T-bet,but reduced those of type 2 cytokines.These results demonstrate that the lung cancer patients had a predominant expression of type 2 cytokines and TTMP could reverse the type 2 dominant status,which might offer an alternative therapeutic regime for lung cancer patients.Cellular & Molecular Immunology.2004;1(1):63-70.
