CD28 family consists of CD28, ICOS, CTLA-4 and PD-1 molecules. The former two are activation receptors and the later two are inhibition receptors. They produce co-stimulatory signals combining with the relevant molecules in B7 family, which plays important role in T cell activation and homeostasis among T subsets. Although the mechanism of signaling by CD28 and CTLA-4 has been well studied, many questions still remain to be answered. Further investigations are required for substantiating the dual-signaling model.
Animals ; Antigens, CD ; Antigens, Differentiation ; immunology ; CD28 Antigens ; immunology ; CTLA-4 Antigen ; Humans ; Immunoglobulin Fc Fragments ; immunology ; Signal Transduction

BACKGROUNDThe hygiene hypothesis has been proposed to explain the pathogenesis of asthma. Allergen exposure was shown to inhibit asthma in an animal model. But the optimal timing of allergen exposure remains unclear. This study aims to explore the time effcct of allergen exposure and the possible mechanisms.

METHODSNeonate Wistar rats were randomly divided into asthma group, control group and day 1, day 3, day 7, and day 14 groups. The day 1, day 3, day 7 and day 14 groups were injected with ovalbumin (OVA) subcutaneously on days 1, 3, 7 and 14 after birth, respectively. Six weeks later, all groups, except the control group, were sensitized and stimulated with OVA to make the asthma model. We observed the pulmonary pathologic changes, detected the regulatory T cells, and CD28 expression level in thymus and spleen by flow cytometry.

RESULTSThe asthmatic inflammation in the day 1, day 3 and day 7 groups, but not the day 14 group, was alleviated. The asthma group and day 14 group had lower proportions of regulatory T cells in the thymus compared with the control group, day 1, day 3, and day 7 groups. There was no significant difference in the CD28 expression levels on the regulatory and conventional T cells among groups. But the control group and the day 1, day 3, and day 7 groups had relatively higher proportions of CD28 positive regulatory T cells in the thymus than the day 14 group and the asthma group.

CONCLUSIONSThere is a "time-window" for early allergen exposure. The impairment of regulatory T cells may promote the development of asthma. Allergen exposure in the "time-window" can make the thymus produce normal quantity of regulatory cells. The CD28 signal on regulatory T cells may participate in the production of regulatory T cells.

Allergens ; immunology ; Animals ; Asthma ; etiology ; CD28 Antigens ; analysis ; physiology ; Disease Models, Animal ; Female ; Ovalbumin ; immunology ; Rats ; Rats, Wistar ; Signal Transduction

The aim of this study was to explore effect of CD8+CD28- T-lymphocyte in the inhibition of mesenchymal stem cells (MSC) on T-lymphocyte proliferation. T cells were harvested by using nylon column and CD8+ T cells were sorted by magnetic beads; the T-lymphocyte proliferation in the presence of PHA was evaluated by MTT; the proportion of CD8+CD28- T cells was assayed by fluorescence-activated cell sorter (FACS). The results showed that MSC inhibited T-lymphocyte proliferation and the inhibitory effect depended on the amount of MSC; the data of FACS indicated that in the CD8+ T cells co-cultured with MSC, CD8+CD28- T cells were up-regulated significantly, compared with the non-treated CD8+ T cells. In conclusion, MSC perform their immunosuppressive function by up-regulation of CD8+CD28- T cells.
Bone Marrow Cells ; physiology ; CD28 Antigens ; analysis ; CD8 Antigens ; analysis ; Humans ; Lymphocyte Activation ; Mesenchymal Stromal Cells ; physiology ; T-Lymphocyte Subsets ; immunology ; Up-Regulation

Adult ; Aged ; Antigens, CD ; biosynthesis ; genetics ; B7-H1 Antigen ; CD28 Antigens ; biosynthesis ; genetics ; Female ; Hepatitis B, Chronic ; immunology ; Humans ; Leukocytes, Mononuclear ; immunology ; Male ; Middle Aged

Animals ; Antigens, CD ; biosynthesis ; genetics ; immunology ; B7-H1 Antigen ; CD28 Antigens ; biosynthesis ; genetics ; Humans ; Immune Tolerance ; Liver ; immunology ; RNA, Messenger ; biosynthesis ; genetics ; T-Lymphocytes ; immunology

OBJECTIVE: To explore the role of DNAM-1 in the activation, proliferation and function of type Ⅰ regulatory T cells (Tr1 cells). METHODS: Anti-CD3/CD28 antibodies were used to stimulate mouse T cells derived from the spleen of wild-type (WT) mice, and the expression level of DNAM-1 in resting and activated Tr1 cells was evaluated with flow cytometry. Na?ve CD4⁺ T cells isolated by magnetic cell sorting from the spleens of WT mice and DNAM-1 knockout (KO) mice were cultured in Tr1 polarizing conditions for 3 days, after which CD25 and CD69 expressions were measured using flow cytometry. The induced Tr1 cells were labelled with CFSE and cultured in the presence of anti-CD/CD28 antibodies for 3 days, and their proliferative activity was analyzed. The expressions of IL-10 and p-STAT5 in DNAM-1-deficient Tr1 cells were detected before and after IL-2 stimulation. RESULTS: The expression level of DNAM-1 was significantly upregulated in CD4⁺ T cells and Tr1 cells after stimulation with anti-CD3/CD28 antibodies (P < 0.05). DNAM-1 knockout did not cause significant changes in the number or proportion of Tr1 cells, but but significantly increased the expression levels of the activation markers CD69 and CD25 (P < 0.05). Compared with WT Tr1 cells, DNAM-1-deficient Tr1 cells exhibited reduced proliferative activity in vitro (P < 0.05) with downregulated IL-10 production (P < 0.05) and decreased expressions of Il-10 and Gzmb mRNA (P < 0.05). In DNAM-1-deficient Tr1 cells, IL-2 stimulation significantly reduced IL-10 secretion level and the expression of p-STAT5 as compared with WT Tr1 cells. CONCLUSION DNAM-1 participate in the activation and proliferation of Tr1 cells and affect the biological functions of Tr1 cells through the IL-2/STAT5 pathway.
Animals ; Antigens, Differentiation, T-Lymphocyte ; CD28 Antigens/metabolism* ; Cell Proliferation ; Cells, Cultured ; Interleukin-10 ; Interleukin-2/metabolism* ; Mice ; RNA, Messenger ; STAT5 Transcription Factor/metabolism* ; T-Lymphocytes, Regulatory

Objective To identify and verify the distribution of Telocytes derived from heterogeneous interstitial cells in the vital organs of ApoE mice.Methods Heart,kidney,and liver tissues were harvested from ApoE adult mice. Immunohistochemical assays were performed by using different immunobiological markers.Results Telocytes were found in these vital organs. The expressions of immunobiological markers differed among different organs. CD34,CD117,and CD28 were positively expressed in Telocytes in cardiac tissue;CD117 and plateled-derived growth factor-Α were negatively expressed in Telocytes in renal tissue;and CD117 and plateled-derived growth factor receptor-Α had negative expression in Telocytes in hepatic tissue. Furthermore,the distribution of Telocytes also differed in the same organ.Conclusions Telocytes exist in the vital organs of ApoE mice,as demonstrated by immunohistochemisty assay. The expressions of immunobiological markers differ among Telocytes in different organs.
Animals ; Antigens, CD34 ; metabolism ; CD28 Antigens ; metabolism ; Kidney ; cytology ; Liver ; cytology ; Mice ; Mice, Knockout, ApoE ; Myocardium ; cytology ; Proto-Oncogene Proteins c-kit ; metabolism ; Telocytes ; cytology

It is known that CD28, a positive costimulatory receptor, plays a very important role in inducing the optimal stimulation of T lymphocytes. CTLA-4 (CD152), however, acts as a negative regulator in T lymphocyte activation. The effect of an feline immunodeficiency virus (FIV) infection on the expression of feline CD28 and CTLA-4 was studied with FIV-infected and uninfected peripheral blood mononuclear cells (PBMC) using a competitive PCR assay. The nature of CD28 and CTLA-4 expression was also examined with fresh and antigen-stimulated PBMC. FIV infection induced a lower expression of CD28, but a higher expression of CTLA-4 in the infected PBMC than in the uninfected PBMC. Relatively high levels of CD28 expression were demonstrated in both the fresh and the antigen-stimulated PBMC. The expression level of CTLA-4 in the freshly isolated PBMC was rather low, however, FIV antigen stimulation induced a relatively high expression of CTLA-4 in feline PBMC.
Animals ; Antigens, CD ; Antigens, CD28/*biosynthesis ; Antigens, Differentiation/*biosynthesis ; Antigens, Viral/*immunology ; Cats ; Cell Survival ; Cells, Cultured ; Gene Expression ; Immunodeficiency Virus, Feline/immunology/*physiology ; Leukocytes, Mononuclear/immunology/*virology ; Polymerase Chain Reaction/veterinary

BACKGROUNDThe expression of the co-stimulatory molecule CD28 and death receptor CD95 on T cells, which change with age, are considered as important immunological parameters of immunosenescence. It is well established that CD28 and CD95 are associated with tumorgenesis and tumor progression, but the relationship between the age-related changes of these two immunological markers and cancer in the elderly is largely unknown.

METHODSThe levels of CD28 and CD95 mRNA in peripheral blood mononuclear cells (PBMCs) from sixty-three elderly patients (aged > or = 60 years) with primary non-small cell lung cancer (NSCLC) were analyzed by real-time fluorescence-based quantitative polymerase chain reaction (FQ-PCR). In addition, twenty young patients (aged < 60 years) with NSCLC, thirty elderly healthy donors and thirty young healthy donors were enrolled as controls.

RESULTSCD28 mRNA levels were significantly lower and CD95 mRNA levels were significantly higher in elderly patients with NSCLC than in the other groups. Similar results were found in elderly healthy donors comparing with young healthy donors. By Logistic regression analysis an increased risk of NSCLC was markedly associated with aging, down-regulation of CD28 mRNA and up-regulation of CD95 mRNA, and CD28 mRNA had an obvious negative correlation with the CD95 mRNA. In addition, the mRNA levels of CD28 and CD95 in the peripheral blood of the elderly patients was closely associated with the tumor node metastasis (TNM) stages, grade of cell differentiation and lymph node metastasis status, but not related to pathological types.

CONCLUSIONSThe results suggest a close relationship between T cell senescence and NSCLC tumour progress in the elderly, and that up-regulation of CD28 mRNA or down-regulation of CD95 mRNA in peripheral blood T cells may play an important role in inhibiting oncogenesis and development of primary NSCLC in the elderly.

Aged ; CD28 Antigens ; genetics ; Carcinoma, Non-Small-Cell Lung ; genetics ; Humans ; Leukocytes, Mononuclear ; metabolism ; Logistic Models ; Lung Neoplasms ; genetics ; Polymerase Chain Reaction ; fas Receptor ; genetics

This study was aimed to establish downstream purification procedure by which the protein of interest can be purified to higher purity rapidly and efficiently. The different combinations of various purification strategies, methods and conditions were compared, including reversed phase chromatography, metal chelating chromatography, anion exchange chromatography, blue dye affinity chromatography, filtration chromatography and so on. The results showed that in reversed phase chromatography, isolated protein of interest was denatured and precipitated immediately after chromatography because methanol or acetonitrile were adopted as the organic phase. In blue dye affinity chromatography expecting to purify the protein of interest in one step, protein of interest was difficultly differentiated from mixed protein as much proteins bound to the chromatography media by non-specific affinity. While there is a translation-enhancing sequence T7-g10 in the PRSETA-B7-2-PE40KDEL expression vector, so it adds 6 histidines to the N terminus of the protein of interest, this allows to purify the protein of interest by metal chelating chromatography. Based on this characteristic, a three-step chromatography line including metal chelating chromatography, anion exchange chromatography and filtration chromatography was finally established after repeated experiments. By this way the purity of protein of interest reached 95% and the total recovery rate was 8%. The result of Western blot indicated that the expressed and purified recombinant B7-2-PE40KDEL could specifically bind with mAb against human B7-2 and multiple antibody against PEA. The cytotoxicity of the recombinant toxin tested by MTT method showed that the B7-2-PE40KDEL could selectively kill Jurkat cell line expressing CD28 receptor well and had no killing effect on the Raji cell line unexpressing CD28 receptor. It is concluded that a high efficient and speedy three-step purification procedure for the purifying recombinant protein B7-2-PE40KDEL was established, and this procedure possess selective killing activity on CD28 positive T lymphocytes.
B7-2 Antigen ; biosynthesis ; genetics ; Bacterial Proteins ; biosynthesis ; genetics ; CD28 Antigens ; immunology ; Cloning, Molecular ; Escherichia coli ; genetics ; Gene Expression ; Humans ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; isolation & purification