High-affinity T cell receptors redirect cytokine-activated T cells (CAT) to kill cancer cells / 医学前沿

Cytokine-activated T cells (CATs) can be easily expanded and are widely applied to cancer immunotherapy. However, the good efficacy of CATs is rarely reported in clinical applications because CATs have no or very low antigen specificity. The low-efficacy problem can be resolved using T cell antigen receptor-engineered CAT (TCR-CAT). Herein, we demonstrate that NY-ESO-1 HLA-A*02:01-specific high-affinity TCR (HAT)-transduced CATs can specifically kill cancer cells with good efficacy. With low micromolar range dissociation equilibrium constants, HAT-transduced CATs showed good specificity with no off-target killing. Furthermore, the high-affinity TCR-CATs delivered significantly better activation and cytotoxicity than the equivalent TCR-engineered T cells (TCR-Ts) in terms of interferon-γ and granzyme B production and in vitro cancer cell killing ability. TCR-CAT may be a very good alternative to the expensive TCR-T, which is considered an effective personalized cyto-immunotherapy.

Prediction and Identification of HLA-A*0201 Restricted CTL Epitopes from Eps8 / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To find and identify HLA-A*0201 restricted cytotoxic T lymphocyte (CTL) epitopes from epidermal growth factor pathway substrate number 8 (Eps8) for specific immunotherapy based on Eps8-derived epitopes in clinic.</p><p><b>METHODS</b>Online biological softwares involved C-proteasomal cleavage, MHC class I binding affinity and TAP transport efficiency were used for prediction of HLA-A*0201 restricted epitopes from Eps8. Then, T2-binding assays and peptide/MHC complex stability tests were used to further verify the predicted epitopes. Specific secretion of IFN-γ from human CTL was assayed using the IFN-γ ELISPOT kit, and cytolytic activity was measured by a 4-h lactate dehydrogenase (LDH) release assay. Finally, the functional effects in vivo were measured in HLA-A*0201/Kb transgenic (Tg) mice.</p><p><b>RESULTS</b>Four natural epitopes were designed through online biological softwares. Of the four epitopes selected, p360-368 was found to have the high binding affinity to HLA-A*0201, while p101-109 and p276-284 showed moderate affinities. DC50 of peptide/MHC complexes of the natural epitopes mentioned were all longer than 8 h. In functional assays with human PBMNC in vitro and in HLA-A*0201/Kb transgenic mice in vivo, CTLs primed by each epitope (p101-109, p276-284 and p360-368) secreted IFN-γ and were toxic to cancer cells from a variety of tissue types in an HLA-A*0201-restricted and Eps8-specific manner.</p><p><b>CONCLUSION</b>Natural epitopes (p101-109, p276-284 and p360-368) may be the HLA-A*0201 restricted epitope derived from Eps8.</p>

A new unconventional HLA-A2-restricted epitope from HBV core protein elicits antiviral cytotoxic T lymphocytes

Cytotoxic T cells (CTLs) play a key role in the control of Hepatitis B virus (HBV) infection and viral clearance. However, most of identified CTL epitopes are derived from HBV of genotypes A and D, and few have been defined in virus of genotypes B and C which are more prevalent in Asia. As HBV core protein (HBc) is the most conservative and immunogenic component, in this study we used an overlapping 9-mer peptide pool covering HBc to screen and identify specific CTL epitopes. An unconventional HLA-A2-restricted epitope HBc141-149 was discovered and structurally characterized by crystallization analysis. The immunogenicity and anti-HBV activity were further determined in HBV and HLA-A2 transgenic mice. Finally, we show that mutations in HBc141-149 epitope are associated with viral parameters and disease progression in HBV infected patients. Our data therefore provide insights into the structure characteristics of this unconventional epitope binding to MHC-I molecules, as well as epitope specific CTL activity that orchestrate T cell response and immune evasion in HBV infected patients.

Relationship between Poor Immunogenicity of HLA-A2-Restricted Peptide Epitopes and Paucity of Naive CD8+ T-Cell Precursors in HLA-A2-Transgenic Mice

We examined the immunogenicity of H-2 class I-restricted and HLA-A2-restricted epitopes through peptide immunization of HLA-A2-transgenic mice that also express mouse H-2 class I molecules. All four of the tested epitopes restricted by H-2 class I robustly elicited T-cell responses, but four of seven epitopes restricted by HLA-A2 did not induce T-cell responses, showing that HLA-A2-restricted peptide epitopes tend to be poorly immunogenic in HLA-A2-transgenic mice. This finding was confirmed in HLA-A2-transgenic mice infected with a recombinant vaccinia virus expressing hepatitis C virus proteins. We examined the precursor frequency of epitope-specific naive CD8+ T cells in HLA-A2-transgenic and conventional C57BL/6 mice and found that the poor immunogenicity of HLA-A2-restricted peptide epitopes is related to the paucity of naive CD8+ T-cell precursors in HLA-A2-transgenic mice. These results provide direction for the improvement of mouse models to study epitope repertoires and the immunodominance of human T-cell responses.

Construction of three HLA-A*0201-peptide tetramers and their preliminary application in detection of vitiligo-specific cytotoxic T lymphocytes / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To construct vitiligo-specific HLA-A*0201-peptide tetramers and to apply the constructed tetramers in detection of vitiligo-specific cytotoxic T lymphocytes (CTL).</p><p><b>METHODS</b>Proteins HLA-A0201*-BSP and β2M were obtained by effective prokaryotic expression. The purified proteins were refolded with vitiligo antigen peptides MelanA 26-35, gp100 209-217, and tyrosinase 1-9, respectively to form HLA-A*0201-peptide complex. The complex was biotinylated by BirA enzyme and purified by gel-filtration chromatography. The tetramers were generated by mixing the complex with phycoerythrin (PE)-streptavidin at a ratio of 4∶1 and identified by Dot-blot assay. The capacity of tetramer to detect vitiligo-specific CTL was analyzed by flow cytometry.</p><p><b>RESULTS</b>The biotinylation of vitiligo-specific HLA-A*0201-peptide tetramers were successfully performed by Dot-blot. Flow cytometry analysis indicated that the tetramer effectively bound to specific CTL from peripheral blood of patients with vitiligo.</p><p><b>CONCLUSION</b>Three kinds of biotinylated vitiligo-specific HLA-A*0201-peptide tetramers have been constructed successfully. The tetramer can detect antigen specific CTL from patients with vitiligo.</p>

Relationship between serum HBV DNA level and follicular helper T lymphocyte in patients with chronic hepatitis B and its significance / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To explore relationship between HBV DNA level and peripheral blood follicular helper T lymphocyte (Tfh) in patients with chronic hepatitis B (CHB) and its significance.</p><p><b>METHODS</b>HBV DNA levels of 179 cases of CHB patients with positive HBV DNA, positive HBeAg and positive human leukocyte antigen(HLA)-A2 were tested with real time fluorescent quantitative PCR. Tfh and HBV specific CTL were tested with flow cytometry. IL-21 was also tested. 179 cases of CHB patients were divided into group A and group B based on HBV DNA levels, 86 cases in group A, HBV DNA levels were 10(4)-10(5) copies/ml, 93 cases in group B, HBV DNA levels were 10(6)-10(7) copies/ml. Above testing indexes of the two groups were compared.</p><p><b>RESULTS</b>HBV DNA levels of group A were (4.85 +/- 0.37) log10 copies/ml, HBV DNA levels of group B were (6.83 +/- 0.31 ) log10 copies/ml, t = 27.31, P < 0. 001; Tfh of group A was (5.96 +/- 1.59)%, higher than that of group B (3.71 +/- 2.15)%, t = 4.92, P < 0.01; IL-21 of group A was (42.61 +/- 15.11)ng/L, higher than that of group B (14.91 +/- 3.15) ng/L, t = 8.62, P < 0.01; HBV specific CTL of group A was (0.36 +/- 0.08)%, higher than that of group B (0.18 +/- 0.06)%, t = 19.99, P < 0.001.</p><p><b>CONCLUSION</b>Serum HBV DNA level of CHB patients is related to the level of peripheral blood Tfh level: patients with low HBV DNA level have high Tfh level, high IL-21 level and high HBV specific CTL level. Patients with high HBV DNA level have low Tfh level, low IL-21 level and low HBV specific CTL level. The mechanism of baseline HBV DNA level affecting anti-viral therapy may be related to Tfh level.</p>

PD-1 expression in HBcAg-specific CD8+ T cells of adolescents with chronic HBV infection / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the differential expression of programmed death-1 (PD-1) in the hepatitis B core antigen (HBcAg)17-28-specific CD8+ T cell subsets of adolescent patients with chronic hepatitis B virus (HBV) infection during the immune tolerant phase and the immune clearance phase.</p><p><b>METHODS</b>A total of 105 patients between the ages of 12-28 years old (mean age 17.20+/-6.35) with chronic HBV infection and 15 healthy age-matched individuals were enrolled in the study. The patients were divided into two groups according to their current status in immune clearance phase (n = 55) or immune tolerant phase (n = 50), as determined by hepatic biopsy pathology. Flow cytometry was used to detect HLA-A2 type and PD-1 expression on peripheral blood mononuclear cells (PBMC) and HBcAg17-28-specific CD8+ T cells. PD-1 mRNA levels in PBMCs were measured by reverse transcription-polymerase chain reaction (RT-PCR). Independent samples t-test was used to compare means between the two groups, and one-way ANOVA was used to compare means among multiple groups. Pearson's correlation coefficient was used to assess the significance of correlation.</p><p><b>RESULTS</b>The frequency of HBcAg18-27-specific CD8+ T cells was significantly higher in the immune clearance phase group than in the immune tolerant phase group (t = 18.08, P less than 0.01), but the expression of PD-1 on the HBcAg18-27 specific CD8+ T cells was significantly lower in the immune clearance phase group than in the immune tolerant phase group (t = 4.72, P less than 0.01). A negative correlation existed between the frequency of HBcAg18-27-specific CD8+ T cells and PD-1 expression (r = -0.463, P less than 0.01). A positive correlation existed between HBV viral load and PD-1 expression on the HBcAg18-27-specific CD8+ T cells in chronic HBV infection patients (r = 0.882, P less than 0.01), and there was a negative correlation between PD-1 expression levels on HBcAg18-27-specific CD8+ T cells and hepatic tissue inflammation score (r = -0.76, P less than 0.01). PD-1 mRNA in PBMCs was significantly higher in the immune tolerant phase group than in the immune clearance phase group (t = 30.89, P less than 0.01).</p><p><b>CONCLUSION</b>Up-regulated expression of PD-1 is associated with HBV-specific CD8+ T cells and may play a crucial role in inhibiting their function during the immune tolerance phase of chronic HBV infection in adolescents.</p>

Neonatal Alloimmune Thrombocytopenia Caused by Anti-HLA-A2 Alloantibodies Determined by Luminex Single Antigen Bead Assay

Neonatal alloimmune thrombocytopenia (NAIT) occurs when maternal alloantibodies react to antigens expressed on fetal platelets, which is mainly platelet-specific alloantigen or HLA, resulting in their immune destruction. Here, we described a patient who suffered from NAIT caused by anti-HLA-A2 antibody. Sera from the mother and the newborn were screened for human platelet antigen-specific antibodies and HLA antibodies by ELISA, and HLA antibodies were detected in both of them. The antibody specificity was identified as anti-HLA-A2 by Luminex single antigen bead assay. HLA typing results showed that patient's father descended HLA-A2 antigen on the patient and the mother was HLA-A2 negative. It is most conceivable that anti-HLA-A2 alloantibody in the mother's sera crossed the placenta and subsequently caused NAIT in the case presented. The patient received platelet concentrates, oral steroid and intravenous globulin and platelet count increased to 120x10(9)/L on the 90th day of life. The Luminex single antigen bead assay used in this case is highly sensitive and specific assay to determine antibody specificity and it is faster and more convenient for routine use in clinical laboratory so that this assay could be useful to diagnose NAIT caused by HLA antibodies and treat such NAIT patients with HLA matched platelet transfusion.

Dynamic changes and clinical significance of HBcAg18-27 specific cytotoxic T lymphocytes in acute hepatitis B patients / 中华肝脏病杂志

This report aims to investigate the dynamical changes of HBcAg18-27 epitope specific cytotoxic T lymphocytes(CTL), alanine aminotransferase (ALT), HBV DNA and HBsAg in peripheral blood of acute hepatitis B patients, and to explore the roles of HBcAg18-27-specific CTLs in virus clearance and liver injury. Acute hepatitis B (AHB) and chronic hepatitis B (CHB) patients were divided into two groups according to results of HLA-A0201. Patients with positive HLA-A0201 were classified into HBcAg-specific CTL group and those with negative HLA-A0201 were referred as control group. The specific CTLs were stained with HLA-A0201 limited HBcAg18-27 epitope MHC-Pentamer and the frequencies of CTLs, T, B, NK and NKT cells were detected by flow cytometry (FCM). The serum ALT, HBV DNA and HBsAg were examined using speed analysis, quantitative PCR and abbott chemiluminescent technology. The frequencies of HBcAg18-27-specific CTLs in AHB patients were higher in the early three weeks as compared to the late three weeks. The apex time of HBV-specific CTL frequencies lagged behind those of HBV DNA, HBsAg and ALT. The loss of HBsAg in patients with high frequencies of HBV-specific CTL was earlier than that in patients with low frequencies (t = 2.018, P value is less than 0.05). In the second week the peak frequencies of CD3+CD8+ cells overlapped with that of HBcAg18-27-specific CTLs and with a positive correlation between (r = 0.420, P value is less than 0.05). During the early stages of AHB, the frequencies of NK and NKT cells were found significantly lower than that of control group and CHB group and the levels were back to normal after recovery. Moreover, a negative correlation existed between the frequencies of NK cells and the dynamic changes of HBcAg18-27-specific CTLs (r = -0.435, P value is less than 0.01) in AHB group. The frequencies of HBcAg18-27-specific CTLs were significantly higher as compared to CHB group in the first three weeks (z = -3.258, -4.04, and -3.259, P value is less than 0.01). The early loss of HBsAg was closely related to the high frequencies of HBcAg18-27 specific CTLs in AHB patients. HBcAg-specific CTL frequencies in peripheral blood could be used to predict clinical outcome after HBV infection. The frequencies of CD8+ T cells can reflect the changes of frequencies of HBcAg-specific CTL during acute HBV infection.

Association of serum HBV DNA level with cytotoxic T lymphocytes in patients with HBV-induced hepatic cirrhosis / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To explore the association of serum HBV DNA level with HBV-specific and nonspecific cytotoxic T lymphocytes (CTL) in patients with HBV-induced hepatic cirrhosis.</p><p><b>METHODS</b>120 patients with HBV-induced hepatic cirrhosis who were positive for HBV DNA, HBeAg and human leucocyte antigen (HLA)-A2 were enrolled in this study. The level of HBV DNA was determined by real time fluorescence quantitative polymerase chain reaction (PCR). HBV-specific and nonspecific CTL were detected by flow cytometry. Liver function tests were done in the 120 patients. The 120 patients were divided into group A and B based on their HBV DNA levels. In group A, there were 68 patients with HBV DNA level of 3-4 log10 copy/ml, and in group B, 52 with 5-6 log10 copy/ml. HBV-specific and nonspecific CTL and liver function were compared between the two groups.</p><p><b>RESULTS</b>HBV DNA levels were (3.68 +/- 0.19) and (5.97 +/- 0.32) log10 copy/ml in Group A and B respectively with P < 0.001. HBV-specific CTL was higher in group A (0.33% +/- 0.04%) than in group B (0.11% +/- 0.01%) with P < 0.001. HBV-nonspecific CTL were (11.99% +/- 1.51% ) and (11.91% +/- 1.61%) in group A and B respectively with P > 0. 05.</p><p><b>CONCLUSION</b>The level of serum HBV DNA is related to the levels of HBV-specific CTL in patients with HBV-induced hepatic cirrhosis. Patients with higher HBV DNA had lower levels of HBV-specific CTL, and the damage to liver function was severe because of higher levels of HBV DNA. Patients with lower HBV DNA had higher levels of HBV-specific CTL which predict good anti-viral effect.</p>

Auto-dendritic cell vaccines pulsed with PSA, PSMA and PAP peptides for hormone-refractory prostate cancer / 中华男科学杂志

<p><b>OBJECTIVE</b>To investigate the clinical safety and effects of auto-dendritic cells pulsed with HLA-A201-binding peptides prostate-specific antigen (PSA) , prostate-specific membrane antigen (PSMA) and prostatic acid phosphatase (PAP) in the treatment of hormone-refractory metastatic prostate cancer (HRPC).</p><p><b>METHODS</b>Sixteen HRPC patients with positive HLA-A201 were enrolled and their monocytes isolated and induced into dendritic cells with the combination of rhGM-CSF and rhIL4. The patients were inoculated subcutaneously near the inguinal region with auto-DCs pulsed with peptides PSA (KLQCVDLHV) , PSMA (ALDVYNGL L) and PAP (LLHETDSAV) every 2 weeks for 4 times, and the immunological and clinical responses were examined within 1 -2 weeks after the final vaccination.</p><p><b>RESULTS</b>Vaccination of dendritic cells was well tolerated and no toxicity was observed. The cytokine levels in the serum such as IL-2, IL-12 and IFN-gamma were significantly increased after the vaccination (P < 0.01). The delayed type hyper- sensitivity (DTH) test was positive in 4 of the patients (4/11), the percentage of antigen-special IFN-gamma+ CD8+ T increased in 5 (5/11), the level of the tumor marker PSA decreased in 6 (6/16) , hydrops abdominis reduced in 1 (1/16), and the size of the cervical lymph node lessened in 1 (1/16). Three patients showed partial remission (PR), 7 stability of the disease (SD), and the other 6 progression of the disease (PD).</p><p><b>CONCLUSION</b>Auto-DC vaccines loaded with PSA, PSMA and PAP peptides, capable of eliciting specific immune responses in HRPC patients, is a safe and effective option for the treatment of advanced HRPC.</p>

Application of HLA-A*0201/WT1 pentamer combined with intracellular IFNgamma+ staining in detecting circulating WT1 specific T cells in leukemia / 中国实验血液学杂志

This study was purposed to investigate the value of combination of pentamer and intracellular IFNgamma staining in the qualitative and quantitative detection of circulating antigen-specific T cells. WT1 expressions in 14 HLA-A*0201+ patients and their matched donors were detected by RT-PCR, and circulating WT1 specific T cells were assayed by HLA-A*0201/WT1 pentamer combined with intracellular IFNgamma+ staining. The results showed that the low level of WT1 expression was found only in 2 cases out of 14 donors, but different levels of WT1 expression could be observed in all leukemic patients. The WT1+CD8+ CTL and WT1+IFNgamma+ cells did not detected in all 14 donors, but WT1+CD8+ CTL cells in 2 patients and WT1+IFNgamma+ cells in 3 patients could be detected before transplantation respectively, there was no significant difference between them, while the WT1+CD8+ CTL cells and WT1+IFNgamma+ cells both could be detected in all 14 patients after transplantation, the positive detection rate after transplantation was obviously higher than that before transplantation. The WT1+CD8+ and WT1+ IFNgamma+ cells could be detected within 30 days after transplantation, but the positive detection rate of WT1+IFNgamma+ cells was higher than that of WT1+CD8+ CTL cells (p=0.014). The median peak value of WT1+CD8+ CTL cells was 0.18% in 14 patients, and the median peak value of WT1+IFNgamma+ cells was 0.83% in 14 patients, the later was significantly higher than former. The median peak time of WT1+CD8+ CTL cells was 75 days after transplantation, while the WT1+IFNgamma+ cells was 105 days after transplantation, there was no significant difference between them. It is concluded that pentamer and intracellular IFNgamma staining may effectively detect circulating WT1 specific T cells in leukemic patients, and the combination of these two methods profit to the exact qualitation and quantitation of circulating antigen-specific T cells.

Pentamer guided HLA-restricted epitope identification for mucoprotein 4 antigen of pancreatic ductal adenocarcinoma / 中华外科杂志

<p><b>OBJECTIVES</b>To identify HLA-restricted epitope of mucoprotein 4 (MUC4) antigen as a tumor associated antigen of pancreatic ductal adenocarcinoma (PDAC), and to validate its natural presentation in PDAC patient peripheral blood.</p><p><b>METHODS</b>Two epitope prediction databases (SYFPEITHI and ProPred-I) were used to predict HLA-A*0201 restricted MUC4 epitope, T2 cell assay was used to determine the peptide binding affinity with HLA-A*0201 molecule. Dendritic cells (DCs) were induced from the HLA-A* 0201-positive healthy individuals' peripheral blood mononuclear cells (PBMC). Mature DCs were pulsed with synthesized peptides. Autologous CD8(+) T cells from the HLA-A* 0201 healthy donor were stimulated with the peptide-pulsed DCs as CTL. CTL activity was assessed by lactate dehydrogenase release assay and IFN-γ released by enzyme-linked immunospot assay. Pentamer was synthesized for HLA-A* 0201 restricted epitope P1126, then was used to detect specific CTL in PBMC of PDAC patients.</p><p><b>RESULTS</b>Five candidate HLA-A*0201 epitopes were predicted, LLLGVGTFV (P1125) and LLGVGTFVV (P1126) were determined as the two with more HLA-A*0201 affinity. Mature DCs could be induced from PBMCs. CTL induced by peptide P1126 could lyses T2 cells pulsed with peptide P1126 and HCT-116 cells [MUC4(+), HLA-A2(+)]. The number of CTL induced by peptide P1126 which could secret IFN-γ (130.3 ± 6.6) was obviously higher than that in the negative group. By Pentamer assay, P1126-pentamer and CD8 double positive CTL could be detected in PBMC of PDAC patients with MUC4(+) than patients with MUC4(-), but no significant difference of CTL frequency between patients with HLA-A2(+) and with HLA-A2(-) in MUC4(+) PDAC patients.</p><p><b>CONCLUSIONS</b>Tumor associated antigen MUC4-derived HLA-A* 0201-restrictive cytotoxic T lymphocyte (CTL) epitope P1126 can induce CTL reaction. The CTL can secret immunologic active material to induce the specific target cells lysis. P1126 epitope can be naturally presented in PBMC of PDAC patients, but its HLA-restriction may not be perfect.</p>

Determination of circulating HBV specific CD8+ T cells in hepatitis B patients by flow cytometry and its clinical significance / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To explore the levels of circulating HBV specific CD8+ T cells in hepatitis B patients and analysis its clinical significance.</p><p><b>METHODS</b>HBV specific CD8+ T cells in whole blood samples of twenty-five acute hepatitis B patients, thirty-five chronic hepatitis B patients and ten healthy control were stained with pentamers complex of HLA-A2 and HBV core 18-27 peptide and counted by flow cytometry.</p><p><b>RESULTS</b>The medians of HBV core 18-27 specific CD8+ T cells quantities among total CD8+ cells were 2.93% (1.12% -0.63%) in 12 HLA-A2+ acute hepatitis B patients and 0.75% (< 0.01% - 1.76%) in 16 HLA-A2+ chronic hepatitis B patients respectively. There was showed a marked significant between the two groups (P < 0.01). The medians of HBV core 18-27 specific CD8+ T cells of 10 HLA-A2+ healthy control, 13 HLA-A2- acute hepatitis B patients and 19 HLA-A2- chronic hepatitis B patients were all lower than 0.02% separately.</p><p><b>CONCLUSION</b>HLA-peptides pentamers staining flow cytometry is a direct ex vivo method to detect the levels of circulating HBV specific CD8+ T cells which may be play a crucial role in complete clearance of HBV and relates to clinical consequence in hepatitis B patients.</p>

Activation of anti-tumor cytotoxic T lymphocytes by fusion of human dendritic cells and melanoma cells / 中南大学学报(医学版)

OBJECTIVE@#To determine the effect of activation of specific anti-tumor cytotoxic T lymphocytes (CTL) and the ability of cross-presentation in vitro by fusion of HLA-A2+ human dendritic cells (DCs) with HLA-A2- melanoma cells.@*METHODS@#The HLA-A2+ human dendritic cells and HLA-A2- melanoma cells were fused by PEG and were cultivated in complete RPMI1640 media containing FCS (10%) and GM-CSF for 24-48 h, and then co-cultured fusion cells with Melan-A specific T cells. HLA-A2- melanoma cells were negative control,While T2 cells and DC+Pts were positive control. The activation of anti-tumor CTL elicited by the fusion cells was detected by intracellular cytokine staining.@*RESULTS@#The immature DC could express CD80, CD83, CD86, HLA-DR, and HLA-ABC,but the mature DC induced by TNF-alpha, PGE-2, and CD40L further highly expressed above molecules. The rate of specific CTL cells primed by the fusion cells was 16.72%+/-4.26%, negative control was 0.21%+/-1.84%,and positive control was 28.60%+/-5.67%. The CTL from vaccine by fusing DC and LAR6 induced lysis of HLA-A2+ LAR1 cells.@*CONCLUSION@#The HLA-A2 restricted specific anti-tumor CTL can be induced in vitro by fusion of HLA-A2+ human dendritic cells with HLA-A2- melanoma cells.

Activation of specific T lymphocyte induced by artificial antigen presenting cell complex in vitro / 中国实验血液学杂志

This study was aimed to investigate the effect of artificial antigen-presenting cells (aAPCs) on inducing activation and proliferation of specific T-lymphocytes through stimulating biological function of dendritic cells with aAPCs in vitro. The specific antigen of chronic myeloid leukemia CML-28 was screened as objective antigen peptide by using magnetic microbeads as vector; the CML-28 epitope sequence (Vltfaldsv) was obtained by antigen epitope prediction software; this epitope was coupled with MHC molecule and used as first signal molecule, the B7-1 molecule was used as second signal molecule; these 2 molecules simultaneously were loaded onto surface of magnetic microbeads so as to contract aAPC complex. The bone marrow mononuclear cells were derived from HLA-A2(+) healthy bone marrow donors, CD8(+) T lymphocytes were screened and co-cultured with aAPC complex. During culture the 5, 6-carboxyfluorescein diacetate succinimidyl ester (CFSE) was added and proliferation of T-lymphocytes was detected by CPSE and proliferation level of specific T lymphocytes was detected by flow cytometry. The results showed that the proliferation level of CML-28 specific T lymphocytes obviously increased in experimental group, average level was 17.34 +/- 0.65%, while average level in control was 2.25 +/- 0.43%, there was significant difference between them (p < 0.01). It is concluded that the aAPC complex can mimic human APCs in vitro, and stimulate activation and proliferation of CD8(+) specific T lymphocytes.

Comparison of two transmemembrane proteins as fusion partner for protein expression on the surface of cell / 生物工程学报

The expression of a soluble protein on cell surface is often desirable for study of a functional protein, wide application of a protein or investigation of protein-protein interaction. The expression of a soluble protein on the surface of a cell is often achieved by genetically linking a protein to the extra-cellular fragment of a transmembrane partner. In this study, the myc epitope was linked with N terminal of transmembrane proteins either A2TM or deltaLNGFR amplified by overlapping PCR. The plasmids expressing fusion protein were transfected into 293FT cells and the expression of target proteins was evaluated by fluorescent microscope, flow cytometry and Western blotting. The results of flow cytometry revealed that both A2TM and deltaLNGFR were expressed on the cell surface, but A2TM could only be detected with high copy number. Western blotting showed that the expression level of deltaLNGFR was very high and protein was heavily glycosylated, by contrast the expression of A2TM was hardly detected. The results indicate that glycosylated deltaLNGFR is a good candidate partner for the expression of a soluble protein on the cell surface.

Factors affecting the presentation of exogenous hepatitis B virus core antigen.

Hepatitis B virus core antigen (HBcAg) plays a critical role in terminating acute Hepatitis B virus infection and may be used as a potential vaccine candidate. The cell surface major histocompatibility complex (MHC) class 1 molecules are thought to be involved in the presentation of HBcAg. Surface MHC class 1 HLA A2 heavy chain (HC) and trimeric molecules were characterized on transfected Hela cells used as antigen presenting cells (APC) for the presentation of HBcAg. The results show that antibodies against HC HLA A2 and trimeric HLA-A2 molecules resulted in increased activation of HBcAg 18-27 minimal peptide specific cytotoxic T lymphocytes (CTLs), while the addition of exogenous beta2-microglobulin decreased the activation of HBcAg specific CTLs. Further, specific CD8+ T cells were activated only when Hela cells as APCs were primed with HBcAg (peptide, soluble or embedded on virosomes) at pH 6.5.

Identification of a naturally presented MAGE-A3 epitope on the surface of HLE cell line by mass spectrometry / 中华外科杂志

<p><b>OBJECTIVE</b>To identify a naturally presented HLA-A2-restricted epitope of MAGE-A3 antigen, FLWGPRALV (MAGE-A3(271 - 279)), on the surface of a human hepatocellular carcinoma (HCC) cell line HLE.</p><p><b>METHODS</b>Synthetic peptide FLWGPRALV, served as positive control target, was analyzed by HPLC and HPLC-ESI-TOF-MSMS, in order to determine its HPLC elution time, mass-spectrometric characteristics and the lowest detection limitation by the two approaches. 3 x 10(9) HLE cells were collected, peptides naturally presented by major histocompatibility complex (MHC) molecules on the cell surface were isolated by mild acid elution, and concentrated by lyophilization, then the mixtures of peptides were fractioned by HPLC. The ingredient ranged from 2 min before the elution time determined by the synthetic peptide to 2 min after that was collected, concentrated by lyophilization, and analyzed by HPLC-ESI-TOF-MSMS, to identify the existence of the MAGE-A3(271 - 279) peptide.</p><p><b>RESULTS</b>The HPLC-ESI-TOF-MSMS detection provided an evidence for the existence of a doubly charged ion of (m/z)(2) 529.9, which was further analyzed by collision induced dissociation. The doubly charged ion was ultimately identified as the MAGE-A3(271 - 279) peptide, its amino sequence was FLWGPRALV and its molecular weight was 1058.4 Da.</p><p><b>CONCLUSIONS</b>MAGE-A3(271 - 279) epitope could be naturally presented by HLA-A2 molecules to the surface of HCC cell line and MAGE-A3(271 - 279) peptide may have potential immunotherapeutic value in HCC patients.</p>

Construction and characterization of soluble HLA-A*0201-PR1 complex / 中国实验血液学杂志

This study was aimed to construct the soluble HLA-A*0201-PR1 complex for preparation of HLA-A*0201-PR1 tetramer. The recombinant HLA-A*0201-BSP (BirA substrate peptide) fusion protein as heavy chain and beta(2)-microglobulin (beta(2) m) as light chain were expressed highly as insoluble aggregates in Escherichia coli and then purified with gel filtration, and the final purity reached above 90%. The two subunits were refolded to form an HLA-A*0201-peptide complex by dilution method in the presence of an antigenic peptide PR1, a HLA-A2-restricted peptide from proteinase 3 (aa 169 - 177, VLQELNVTV). Refolded HLA-A*0201-PR1 complex was biotinylated using a BirA enzyme and purified by anion exchange chromatography on a Q-Sepharose (fast flow) column. The extent of reconstitution of the HLA-A*0201-PR1 complex was analyzed by HPLC gel filtration. The refolded and biotinylated products were detected by Western blot and ELISA with monoclonal antibody BB7.2 that recognized the natural conformations of HLA-A2 and streptavidin. The results showed that the refolded complex was composed of HLA-A*0201-BSP aggregate, HLA-A*0201-PR1 complex and beta(2) m, and reconstitution yields of 18% with PR1 was obtained. Refolded HLA-A*0201-PR1 complex could be confirmed by practical immunological method and biotinylated efficiently. It is concluded that the refolding and biotinylation of HLA-A*0201-PR1 complex is successfully obtained. This work provides the basis for the preparation of HLA-A*0201-PR1 tetramer.