Elevated major histocompatibility complex class I expression protects T cells from antibody- and macrophage-mediated deletion

Downregulation of the H-2Kd gene by siRNA affects the cytotoxicity of murine LAK cells

To investigate the effect of the H-2K^d gene on the lymphocyte membrane, we constructed a small interfering RNA (siRNA) that targets the H-2K^d gene and compared the cytotoxicity of mouse lymphokine-activated killer (LAK) cells with different H-2K^d expression states. H-2K^d-targeting siRNA was transfected into spleen lymphocytes of BALB/C mice. Flow cytometry (FCM) was then performed to examine the expression of the H-2K^d gene in the transfected and control cells. Additionally, the cytotoxicity of the transfected cells toward the H22 and K562 cell lines was evaluated in vitro using the LDH release assay. H-2K^d-targeting siRNA significantly reduced the expression levels of the target protein, whereas pure transMessenger and non-silencing siRNA did not inhibit H-2K^d expression at the concentrations tested. The cytotoxicity of siRNA-treated LAK cells toward H22 and K562 cells was reduced significantly. The knockdown of H-2K^d gene expression by siRNA may be associated with LAK cell cytotoxicity toward neoplasm cell lines.

HLA Class I Expressions on Peripheral Blood Mononuclear Cells in Colorectal Cancer Patients

OBJECTIVE

To investigate the expression change of human leukocyte antigen (HLA) class I on human peripheral blood mononuclear cells (PBMCs) at both mRNA and protein levels, and to evaluate its roles in the development of colorectal cancer (CRC).

METHODS

In the present study, 50 patients with CRC, 35 patients with benign colorectal lesion and 42 healthy volunteers were enrolled. Expression levels of HLA class I mRNA and protein were determined using real-time quantitative reverse transcription PCR (RT-PCR) and flow cytometry analysis, respectively.

RESULTS

The expression levels of HLA class I mRNA and proteins were not influenced by age and gender. The relative ratios of HLA class I mRNA were 0.99±0.27 in healthy controls, 0.76±0.19 in benign patients, and 0.48±0.21 in CRC patients. Mean fluorescence intensities of HLA class I were 145.58±38.14 in healthy controls, 102.05±35.98 in benign patients and 87.44±34.01 in CRC patients. HLA class I on PBMCs was significantly down-regulated at both mRNA and protein levels in patients with stage III and IV CRC. CRC patients with lymph node metastasis also showed a decreased HLA class I expression at protein level.

CONCLUSION

HLA class I expressions on PBMCs are associated with staging of CRC and lymph node metastasis. Monitoring the expression of HLA class I on PBMCs may provide useful information for diagnosis and metastasis judgement of CRC.

Human leukocyte antigen class I on peripheral blood mononuclear cells as a non-invasive biomarker for esophageal cancer

Esophageal cancer (EC) is a common malignant cancer threatening people's health. There are no universally accepted parameters for its early diagnosis. The aim of this study was to observe the expression of human leukocyte antigen class I (HLA-I) on peripheral blood mononuclear cells (PBMCs) of EC patients and in individuals of high-incidence area of EC so as to evaluate the feasibility of using this parameter as a potential non-invasive biomarker for the early diagnosis of EC. The present study enrolled 58 pathological confirmed EC patients, 46 patients with benign esophageal disease, and 65 healthy volunteers. Expression levels of HLA-I protein and mRNA on PBMCs were determined by flow cytometry and quantitative reverse transcriptase polymerase chain reaction, respectively. Then, 181 volunteers from Lijiadian, a village with high morbidity of EC, and 153 age- and gender-matched health volunteers were involved in this study to observe HLA-I expressions in individuals of high-incidence area of EC. Compared with benign esophageal disease and health volunteers, the expressions of HLA-I protein and mRNA on PBMCs of EC patients are significantly decreased, especially in patients with stage III and IV EC, but was not influenced by patient's age and gender. Furthermore, individuals of high-incidence area of EC also show downregulated HLA-I protein, but not mRNA, expression on PBMCs. Altogether, HLA-I expression on PBMCs of EC patients and individuals from high-incidence area of EC is downregulated, and this parameter might be used as a potential predictor of EC.

Acute rejection correlates with expression of major histocompatibility complex class I antigens on peripheral blood CD3(+)CD8(+) T-lymphocytes following skin transplantation in mice

This study investigated major histocompatibility complex class I (MHC-I) antigen expression on peripheral blood T-cells after transplantation to assess its potential as an early marker of acute graft rejection (AGR). Using a mouse model with or without immunosuppressive treatment, the expression of MHC-I antigens on CD3(+)CD8(+) T-lymphocytes was assessed by flow cytometry following syngeneic graft (n = 138) or allograft (n = 138) skin transplantation. The occurrence of AGR was assessed by examining the degree of lymphocyte and monocyte infiltration in transplant biopsies. During AGR, expression of MHC-I antigens increased significantly compared with pre-transplant levels in the allograft group, even with immunosuppressive treatment. The highest expression of MHC-I antigens occurred 5 - 6 days before macroscopic rejection. These results suggest that expression of MHC-I antigens on peripheral blood CD3(+)CD8(+) T-lymphocytes could be used as an early marker for predicting AGR.

The amount of surface HLA-I on T lymphocytes decreases in breast infiltrating ductal carcinoma patients

Human leucocyte antigen class I (HLA-I), which includes HLA-A, -B and -C, is an essential immune factor participating in the antitumour immune response. The changes in HLA-I expression in peripheral blood T lymphocytes in cancer patients have yet to be defined. This study examined the expression of HLA-I on CD4(+) and CD8(+) T lymphocytes in female patients with stage I - IV breast infiltrating ductal carcinoma, benign breast tumour diseases (mammary intraductal papilloma or breast fibroadenoma), and in healthy controls. HLA-I was down-regulated on CD4(+) T lymphocytes from patients with stage III and IV cancer, and on CD8(+) T lymphocytes in patients with stage I - IV cancer compared with healthy controls. HLA-I expression in T lymphocytes may contribute towards immune-balance disorders in tumour patients.

MHC-I recognition by receptors on myelomonocytic cells: New tricks for old dogs?

Receptors on cytotoxic T lymphocytes and natural killer cells play well-established roles in the immunological response and share a common ligand in the form of MHC-I. We discuss how a variety of MHC-I receptors are also expressed on myelomonocytic cells such as macrophages and dendritic cells. Since myelomonocytic MHC-I receptors recognise a broad range of alleles and MHC-I structures, we propose that their task is to discern expression levels and folding forms of MHC. We describe a model in which these recognition events would regulate bidirectional cross talk between cells of innate and adaptive immune systems to organise an ongoing combined immune response. We discuss how such a model is supported by recent literature and might function in a variety of contexts, including immunoregulation during pregnancy. Our model also offers an alternative explanation of immune dysregulation rather than autoimmunity during HLA-B27-associated spondyloarthropathies and addresses a number of conundrums in this field.

Expression and regulation of B7 family molecules on macrophages (MPhi) in preterm and term neonatal cord blood and peripheral blood of adults

BACKGROUND

Macrophage (MPhi) receptors of the B7 family (CD80, CD86) play a crucial role in T cell activation: the lack of costimulation leads to anergy or apoptosis of reactive T cells. MPhi may differentiate into different subsets, the balance of which defines MPhi-dependent T cell reactions. The aim of this study was to examine neonatal and adult T cell response with respect to the costimulatory MPhi-potential in order to identify molecular predictors for the neonatal immune defense.

METHODS

MPhi from peripheral blood (PBMPhi) or cord blood (CBMPhi) were stimulated with interferon-gamma (IFN-gamma), cyclic adenosine monophosphate (cAMP), CD40 ligand (CD40L), or alphaCD3.

RESULTS

As compared to PBMPhi, CBMPhi showed a significantly decreased upregulation of CD80 and/or CD86 after stimulation with IFN-gamma, cAMP, CD40L, and alphaCD3. Accordingly, the proliferative T cell response was impaired in the presence of CBMPhi. The fraction of T cells that underwent cell death was higher, and blast formation was significantly lower than that observed in the presence of PBMPhi.

CONCLUSIONS

CBMPhi, as compared to PBMPhi, delivered fewer costimulatory but more cytotoxic signals to T cells. These observations suggest that MPhi are one factor explaining the suboptimal immune defense of neonates and their increased susceptibility to infection. Using the costimulatory MPhi-potential as a predictor for immune responses requires a separate reference value system in neonatology.