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

Adolescent ; Adult ; Aged ; CD28 Antigens ; biosynthesis ; genetics ; Female ; Genetic Predisposition to Disease ; Hepatitis B, Chronic ; genetics ; Humans ; Male ; Middle Aged ; Polymorphism, Single Nucleotide ; genetics ; Promoter Regions, Genetic ; genetics

OBJECTIVETo explore the silencing effect of short hairpin RNA (shRNA) on the CD28 of mice T lymphocytes by CD28-shRNA expressing plasmid evaluate the interfering effects (chronology and stability) mediated by shRNA and select out the most efficient CD28 shRNA sequence.

METHODSThree CD28 specific and one non-specific shRNA expressing plasmids were constructed and then transfected separately into mice spleen T lymphocytes. Non-transfected cells and non-specific shRNA were taken as controls. Inhibitory effect of CD28 shRNA was demonstrated by real-time quantitative PCR and Western blots. The sequence of the highest RNA interference (RNAi) efficacy was screened.

RESULTS(1) CD28 shRNA expressing plasmids were successfully constructed; (2) Three CD28 specific shRNAs effectively inhibited the expression of CD28 at the mRNA and protein levels, and there was a statistically significant difference comparing with the controls (P < 0.01): The copies of CD28 in mice spleen cells at the mRNA levels were persistently decreased by 99.62%, 99.89% and 99.80% respectively after 20 days, and so did at the protein level [(84.90 +/- 0.65)%, (96.49 +/- 0.03)%, (91.76 +/- 0.32)% respectively]. The highest inhibitory rate was in CD28 shRNA-2 group.

CONCLUSIONS(1) Specific shRNA can mediate long-term and stable silencing effects on CD28 gene; (2) shRNAs matching different sites of CD28 gene exert differential inhibitory effects.

Animals ; CD28 Antigens ; genetics ; Cells, Cultured ; Gene Expression Regulation ; Mice ; Mice, Inbred C57BL ; Plasmids ; genetics ; RNA Interference ; T-Lymphocytes ; metabolism ; Transfection