• Animal cells and systems
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• v.1 no.1
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• pp.157-164
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• 1997

Ly-6E.1 antigen was proposed as a regulatory molecule of T lymphocyte activation, a hematopoietic stem cell marker, a memory cell marker, and an adhesion molecule. Though there were several reports suggesting the presence of Ly-6 ligand, the characterization of the ligand was not yet performed, As an attempt to screen the expression of Ly-6E.1 ligand, we prepared a probe for detecting Ly-6E.1 ligand by producing a fusion protein between Ly-6E.1 and $hlgC_{r1}$, A mammalian cell expression vector with Ly-6E.$1/hlgC_{r1}$ chimeric cDNA was transfected in SP2/0-Ag14 myeloma cells, and stable transfectants were selected. The fusion protein was produced as a dimer and maintained the epitopes for monoclonal antibodies specific for Ly-6E.1 and for anti-human lgG antibody. The purified fusion protein through Gammabind G column was used for FACS analyses for the expression of Ly-6E.1 ligand. The fusion protein interacted with several cell lines originating from B cells, T cells, or monocytes. The fusion Protein also strongly stained bone marrow, lymph node, and spleen cells, but thymic cells weakly, if any. The staining was more obvious in C57BL/6 $(Ly-6^b)$ than Balb/c $(Ly-6^a)$ mice. These results suggest that the interaction of Ly-6E.1 with Ly-6E.1 ligand may function both in the stem cell environment and in the activation of mature lymphocytes. The fusion protein may be a valuable tool in characterization of biochemical properties of the Ly-6E.1 ligand and, further, in isolating its cDNA.

• Molecules and Cells
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• v.41 no.7
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• pp.653-664
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• 2018

The RNA-binding protein tristetraprolin (TTP) binds to adenosine-uridine AU-rich elements in the 3'-untranslated region of messenger RNAs and facilitates rapid degradation of the target mRNAs. Therefore, it regulates the expression of multiple cancer and immunity-associated transcripts. Furthermore, a lack of TTP in cancer cells influences cancer progression and predicts poor survival. Although the functions of TTP on cancer cells have previously been researched, the mechanism of TTP on the interaction between cancer cells with their micro-environment remains undiscovered. In this study, we admed to determine the role of cancer cell TTP during the interaction between tumor and immune cells, specifically regulatory T cells (Tregs). We evaluate the capability of TTP to modulate the antitumor immunity of GC and explored the underlying mechanism. The overexpression of TTP in GC cells dramatically increased peripheral blood mononuclear lymphocyte (PBML) -mediated cytotoxicity against GC cells. Increased cytotoxicity against TTP-overexpressed GC cells by PBMLs was determined by Treg development and infiltration. Surprisingly, we found the stabilization of programmed death-ligand 1 (PD-L1) mRNA was declining while TTP was elevated. The PD-L1 protein level was reduced in TTP-abundant GC cells. PD-L1 gas been found to play a pivotal role in Treg development and functional maintenance in immune system. Taken together, our results suggest the overexpression of TTP in GC cells not only affects cell survival and apoptosis but also increases PBMLs -mediated cytotoxicity against GC cells to decelerate tumor progression. Moreover, we identified PD-L1 as a critical TTP-regulated factor that contributes to inhibiting antitumor immunity.

• The Journal of the Korean Society for Microbiology
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• v.21 no.3
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• pp.311-329
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• 1986

The experimental exposure of animals to sources of ultraviolet radiation (UVR) which emit their energy primarily in the UVB region (280-320nm) is known to result in a number of well-described changes in the recipient's immune competence. Two such changes include a depressed capacity to effectively respond immunologically to transplants of syngeneic UVR tumors and a markedly reduced responsiveness to known inducers of delayedtype (DTH) and contact hypersensitivity (CH) reactions. The results of experiments that were designed to elucidate the mechanisms responsible for UVR-induced immunomodulation have implicated: 1) an altered pattern of lymphocyte recirculation, 2) suppressor T cells(Ts), 3) deviations in systemic antigen presenting cell (APC) potential. 4) changes in the production of interleukin-1-like molecules, and 5) the functional inactivation of epidermal Langerhans cells in this process. The exposure of skin to UVR, therefore, causes a number of both local and systemic alterations to the normal host immune system. In spite of this seeming complexity and diversity of responses, our recent studies have established that each of the UVR-mediated changes is probably of equal importance to creating the UVR-induced immunocompromised state. Normal animals were exposed to low dose UVR radiation on their dorsal surfaces under conditions where a $3.0\;cm^2$ area of skin was physically protected from the light energy. Contact sensitization of these animals with DNFB, to either the irradiated or protected back skin, resulted in markedly reduced CH responses. This was observed in spite of a normal responsiveness following the skin sensitization to ventral surfaces of the UVR-exposed animals. Systemic treatment of the low dose UVR recipients with the drug indomethacin (1-3 micrograms/day) during the UVR exposures resulted in a complete reversal of the depressions observed following DNFB sensitization to "protected" dorsal skin while the altered responsiveness found in the group exposed to the skin reactive chemical through directly UVR-exposed sites was maintained. These studies implicate the importance of EC as effective APC in the skin and also suggest that some of the systemic influences caused by UVR exposure involve the production of prostaglandins. This concept was further supported by finding that indomethacin treatment was also capable of totally reversing the systemic depressions in CH responsiveness caused by high dose UVR exposure (30K joules/$m^2$) of mice. Attempts to analyze the cellular mechanisms responsible established that the spleens of all animals which demonstrated altered CH responses, regardless of whether sensitization was through a normal or an irradiated skin site, contained suppressor cells. Interestingly, we also found normal levels of T effector cells in the peripheral lymph nodes of the UVR-exposed mice that were contact sensitized through normal skin. No effector cells were found when skin sensitization took place through irradiated skin sites. In spite of such an apparent paradox, insight into the probable mechanisms responsible for these observations was provided by establishing that UVR exposure of skin results in a striking and dose-dependent blockade of the efferent lymphatic vessels in all peripheral lymph nodes. Therefore, the afferent phases of immune responses can apparently take place normally in UVR exposed animals when antigen is applied to normal skin. The final effector responses, however, appear to be inhibited in the UVR-exposed animals by an apparent block of effector cell mobility. This contrasts with findings in the normal animals. Following contact sensitization, normal animals were also found to simultaneously contain both antigen specific suppressor T cells and lymph node effector cells. However, these normal animals were fully capable of mobilizing their effector cells into the systemic circulation, thereby allowing a localization of these cells to peripheral sites of antigen challenge. Our results suggest that UVR is probably not a significant inducer of suppressor T-cell activity to topically applied antigens. Rather, UVR exposure appears to modify the normal relationship which exists between effector and regulatory immune responses in vivo. It does so by either causing a direct reduction in the skin's APC function, a situation which results in an absence of effector cell generation to antigens applied to UVR-exposed skin sites, inhibiting the capacity of effector cells to gain access to skin sites of antigen challenge or by sequestering the lymphocytes with effector cell potential into the draining peripheral lymph nodes. Each of these situations result in a similar effect on the UVR-exposed host, that being a reduced capacity to elicit a CH response. We hypothesize that altered DTH responses, altered alloresponses, and altered graft-versus-host responses, all of which have been observed in UVR exposed animals, may result from similar mechanisms.