Third-party Peripheral Blood Mononuclear Cells Research Articles

Imlifidase Inhibits HLA Antibody-mediated NK Cell Activation and Antibody-dependent Cell-mediated Cytotoxicity (ADCC) In Vitro.

Antibody-dependent cell-mediated cytotoxicity (ADCC) is an important pathway responsible for antibody-mediated rejection (AMR). Imlifidase (IdeS) cleaves human IgG into F(ab')2 and Fc fragments, potentially inhibiting ADCC. Here we examined the effect of IdeS on allo-antibody-mediated NK cell activation (Allo-CFC) and ADCC in vitro. For Allo-CFC, normal whole blood was incubated with third-party peripheral blood mononuclear cells (PBMCs) pretreated with anti-HLA antibody positive (HS) or negative (NC) sera to measure IFNγ+ NK cell%. For ADCC, normal PBMCs were incubated with Farage B (FB) cells with HS or NC sera to measure 7-AAD+ lysed FB cell%. To assess the effect of IdeS on these assays, serum-treated PBMCs (Allo-CFC-1) and serum used for PBMC pretreatment (Allo-CFC-2) in Allo-CFC, and serum used for ADCC were preincubated with IdeS. Sera from IdeS-treated patients were also tested for Allo-CFC (Allo-CFC-3). IFNγ+ NK cell% were significantly elevated in HS versus NC sera in Allo-CFC-1 (10 ± 3% versus 2 ± 1%, P = 0.001), Allo-CFC-2 (20 ± 10% versus 4 ± 2%, P = 0.01) and 7AAD+ FB cell% (11 ± 3% versus 4 ± 2%, P = 0.02) in ADCC. These were significantly reduced by IdeS treatment. Patient sera with significantly reduced anti-HLA antibody levels at 1 day postimlifidase lost the capacity to activate NK cells in Allo-CFC-3, but those at 1-3 months postimlifidase regained the capacity. IdeS inhibited NK cell activation and ADCC in vitro and in treated patients. These results and reported inhibition of complement activating anti-HLA antibodies by IdeS suggest its possible role in treatment of AMR.

Characterization, biology, and expansion of regulatory T cells in the Cynomolgus macaque for preclinical studies.

Reliable in vitro expansion protocols of regulatory T cells (Tregs) are needed for clinical use. We studied the biology of Mauritian Cynomolgus macaque (MCM) Tregs and developed four in vitro Treg expansion protocols for translational studies. Tregs expanded 3000-fold when artificial antigen presenting cells (aAPCs) expressing human CD80, CD58 and CD32 were used throughout the culture. When donor peripheral blood mononuclear cells (PBMCs) were used as the single source of APCs followed by aAPCs, Tregs expanded 2000-fold. Tregs from all protocols suppressed the proliferation of anti-CD2CD3CD28 bead-stimulated autologous PBMCs albeit with different potencies, varying from 1:2-1:4 Treg:PBMC ratios, up to >1:32. Reculture of cryopreserved Tregs permitted reexpansion with improved suppressive activity. Occasionally, CD8 contamination was observed and resolved by resorting. Specificity studies showed greater suppression of stimulation by anti-CD2CD3CD28 beads of PBMCs from the same donor used for stimulation during the Treg cultures and of autologous cells than of third-party PBMC responders. Similar to humans, the Treg-specific demethylated region (TSDR) within the Foxp3 locus correlated with suppressive activity and expression of Foxp3. Contrary to humans, FoxP3 expression did not correlate with CD45RA or CD127 expression. In summary, we have characterized MCM Tregs and developed four Treg expansion protocols that can be used for preclinical applications.

Immunogenicity of decidual stromal cells in an epidermolysis bullosa patient and in allogeneic hematopoietic stem cell transplantation patients.

Allogeneic mesenchymal stromal cells (MSCs) are widely used in regenerative medicine, but little is known about their immunogenicity. In this study, we monitored the therapeutic and immunogenic effects of decidual stromal cells (DSCs) from term placentas when used as a therapy for generalized severe junctional epidermolysis bullosa (JEB) (previously termed Herlitz JEB), a lethal condition caused by the lack of functional laminin-332. An 11-month-old JEB patient was treated with five infusions of allogeneic DSCs within a 3-month period. Amniotic membranes (AMs) were applied to severe wounds. After the treatment, wounds started to heal in the middle of the blisters, but the improvements were transient. After two infusions of DSCs, the JEB patient had developed multispecific anti-HLA class-I antibodies. No antibodies to laminin-332 were detected, but the patient had high levels of anti-bovine serum albumin antibodies, which could bind to DSCs. Peripheral blood mononuclear cells (PBMCs) from the patient had a higher proliferative response to DSCs than to third-party PBMCs, which contrasts with the pattern observed in healthy donors. Human DSCs and MSCs induced similar xenoreactivity in mice. Two of 16 allogeneic stem cell-transplanted patients, treated with DSCs for graft-versus-host disease or hemorrhagic cystitis, showed a positive flow cytometric crossmatch test. One patient had anti-HLA antibodies before DSC infusion, whereas the other had no anti-HLA antibodies at any time. AM and DSC infusions may have improved the healing process in the JEB patient, but DSCs appeared to induce anti-HLA antibodies. The risk of alloimmunization by DSCs seems to be low in immunocompromised patients.

Influence of Adoptive Immunotherapy Employing Allograft Liver-Resident Lymphocytes On Alloimmune Responses.

We have shown that an adoptive immunotherapy by using IL-2 activated lymphocytes extracted from allograft liver perfusate, which contains includes abundant IFN-γ producing CD56+ cells, mount an anti-HCC response in liver transplantation (LT) recipients. In this study, we investigated the immunological properties of liver-resident lymphocytes and the influence of immunotherapy with those cells on alloimmune-responses after LT. The liver mononuclear cells (LMCs) extracted from allograft liver perfusate included higher proportion of CD3-CD56+ NK and CD3+CD56+ NKT cells (43.5 ± 10.0 % and 14.7 ± 8.7 %, respectively, n = 5) than the peripheral blood mononuclear cells (PBMCs) from same donors (9.4 ± 2.9% and 2.7 ± 1.2 %, respectively, n = 5). One-way mixed lymphocyte reaction (MLR) assay revealed that the stimulation with the irradiated LMCs lead to the proliferation of allogeneic T cells as well as that with the PBMC from same donors, indicating that the LMCs contain the antigen presenting cells (n = 5 in each). We successfully performed immunotherapy with IL-2-activated LMCs 3 days after living donor LT in 27 recipients with HCC. In those patients and control 25 LT recipients without immunotherapy, MLR assay was performed at 1, 2, 4 and 12 weeks after LT to monitor immune status. In this assay, CFSE-labeled PBMCs from recipients were used as responders. Irradiated autologous, donor, and third-party PBMCs were used as stimulators. After coculture, the responder cells were stained with CD4 or CD8 mAbs, followed by FCM analyses. The proliferation of CD4+ and CD8+ T cell subsets in response to anti-donor and anti-third-party stimuli were analyzed using MLR. Both stimulation indexes of anti-donor CD4+ and CD8+ T cells did not differ between LT recipients treated with immunotherapy and those who did not received immunotherapy during observation period. Acute rejection episode occurred in 2 of the patients who received the immunotherapy (the incidence of rejection = 6.7%), whereas that occurred in 4 of the patients who did not receive the immunotherapy (14.8%). Thus, adoptive immunotherapy with allograft liver-resident lymphocytes did not inflict an acceleration of alloimmune responses/rejection reactions.

Optimization of methodology for production of CD25/CD71 allodepleted donor T cells for clinical use

Immunotherapy with allodepleted donor T cells improves immunity after T cell-depleted hematopoietic stem cell transplantation. We developed a methodology for selective depletion of alloreactive T cells after activation with host antigen-presenting cells by targeting T cells up-regulating CD25 and CD71. Combined depletion of these cells yields a pool of allodepleted donor T cells with antiviral properties with minimal capacity to cause graft-versus-host disease. Mature dendritic cells were irradiated and used to stimulate donor peripheral blood mononuclear cells for 4 days. The co-culture was stained with anti-CD71-biotin followed by CliniMACS CD25 and Anti-Biotin Reagents (Miltenyi Biotec GmbH; Bergisch Gladbach, Germany) before depletion on the CliniMACS Plus (Miltenyi Biotec GmbH). Residual alloreactivity was tested by flow cytometry, a secondary mixed lymphocyte reaction and limiting dilution analysis, and specific anti-viral immunity with pentamer staining. The large-scale protocol was tested under current good manufacturing practice conditions in five donor-recipient pairs of human leukocyte antigen-matched volunteer donors. We developed a closed-system methodology using cell differentiation bags for cell culture and the COBE2991 Cell Processor (CaridianBCT, Lakewood, CO, USA). We also validated an anti-CD71-biotin generated for ex vivo clinical use. In five large-scale runs, the depleted fraction demonstrated excellent viability (99.9%), minimal residual expression of CD3/CD25 and CD3/CD71 (<0.2%) and passed tests for Mycoplasma, endotoxin, bacterial and fungal sterility. In secondary mixed lymphocyte reaction assays, the median response to host after allodepletion was 0%, whereas responses to third-party peripheral blood mononuclear cells were preserved (median, 105%; range 37%-350%). Limiting dilution analysis assays also demonstrated a reduction in response to host (median,-1.11 log) with preservation of third-party responses, and testing with human leukocyte antigen-restricted pentamers showed that populations of Epstein-Barr virus-specific and cytomegalovirus-specific CD8(+) T cells were retained after depletion. We optimized a protocol for the combined immunomagnetic depletion of alloreactive CD25/CD71 T cells under current good manufacturing practice conditions and tested the efficacy in five donor-recipient pairs.

Mixed Chimerism, Lymphocyte Recovery, and Evidence for Early Donor-Specific Unresponsiveness in Patients Receiving Combined Kidney and Bone Marrow Transplantation to Induce Tolerance

We have previously reported operational tolerance in patients receiving human leukocyte antigen-mismatched combined kidney and bone marrow transplantation (CKBMT). We now report on transient multilineage hematopoietic chimerism and lymphocyte recovery in five patients receiving a modified CKBMT protocol and evidence for early donor-specific unresponsiveness in one of these patients. Five patients with end-stage renal disease received CKBMT from human leukocyte antigen-mismatched, haploidentical living-related donors after modified nonmyeloablative conditioning. Polychromatic flow cytometry was used to assess multilineage chimerism and lymphocyte recovery posttransplant. Limiting dilution analysis was used to assess helper T-lymphocyte reactivity to donor antigens. Transient multilineage mixed chimerism was observed in all patients, but chimerism became undetectable by 2 weeks post-CKBMT. A marked decrease in T- and B-lymphocyte counts immediately after transplant was followed by gradual recovery. Initially, recovering T cells were depleted of CD45RA+/CD45RO(-) "naïve-like" cells, which have shown strong recovery in two patients, and CD4:CD8 ratios increased immediately after transplant but then declined markedly. Natural killer cells were enriched in the peripheral blood of all patients after transplant.For subject 2, a pretransplant limiting dilution assay revealed T helper cells recognizing both donor and third-party peripheral blood mononuclear cells. However, the antidonor response was undetectable by day 24, whereas third-party reactivity persisted. These results characterize the transient multilineage mixed hematopoietic chimerism and recovery of lymphocyte subsets in patients receiving a modified CKBMT protocol. The observations are relevant to the mechanisms of donor-specific tolerance in this patient group.

Increased Interleukin-10 Production Without Expansion of CD4+CD25+ T-Regulatory Cells in Early Stable Renal Transplant Patients on Calcineurin Inhibitors

Increasing long-term allograft survival is the main challenge in organ transplantation, and allograft loss due to chronic rejection has been found to correlate with episodes of early acute rejection. It is important to understand the mechanisms that maintain the donor-specific hyporesponsive state. This study prospectively evaluates immune events related to donor-specific hyporesponsiveness in the stable transplant patients on calcineurin inhibitors (CNIs). Peripheral blood mononuclear cells of transplant recipients on CNI (n=19) were tested in mixed lymphocyte reaction (MLR) against donor and third-party peripheral blood mononuclear cells pretransplant and at 6 to 8 weeks, 14 to 18 weeks, and 6 to 8 months posttransplant. Interleukin (IL)-10 and transforming growth factor-beta were quantitated in cultures supernatants by enzyme-linked immunosorbent assay. CD4CD25 T-regulatory cells (Tregs) were enumerated using flow cytometry. All patients showed sharp decline in anti-donor and third-party MLR response at 6 to 8 weeks posttransplant with progressive decline up to 6 to 8 months. This was accompanied by increased IL-10 levels in the supernatant at all the follow-ups. Transforming growth factor-beta level in the supernatant was significantly lower at 14 to 18 weeks. Frequency of CD4CD25 Tregs showed a significant decrease at 6 to 8 weeks posttransplant, which was sustained up to 6 to 8 months. The study shows that the maintenance of good graft function in early posttransplant period in recipients on CNI is associated with a decrease in donor-specific and third-party MLRs. There is a decline in Treg numbers along with increased IL-10 levels. High IL-10, probably from a non-Tregs source, may have an important role in maintaining hyporesponsiveness and good graft function.

Identification and Expansion of Myeloma-Specific Cytotoxic T Cells In Vitro.

Multiple myeloma (MM) has been considered as low immunogenic incurable disease. The attempts has been made to invert the immune status to recognize myeloma cells by T cells or other cells of the immune system. Here we studied biology of myeloma-specific T cells in vitro.Irradiated myeloma cell line ARH 77 has been used as tumor antigen to stimulate peripheral blood mononuclear cells (PBMC) of 8 healthy volunteers. Dendritic Cells loaded by irradiated autologous MM cells has been used to stimulate PBMC of 10 MM patients. Activated responder T cells have been immunomagnetically separated based on surface expression of interferon gamma (Miltenyi Biotech) and expanded in 5 cases by phytohemaglutinin and repeated high-doses of interleukin 2. Cytotoxicity against the original myeloma cells has been tested after the expansion using propidium iodide or 7-amino actinomycin D. Responder T cells were labeled by CFSE to distinguish them from myeloma cells. Third-party PBMC and interferon gamma negative fraction of T cells served as controls.The percentage of interferon gamma positive cells in healthy donors has been enriched from 2.8±0.9 and 2.6±0.8 to 48.6±23.4 and 73.2±25.9 of CD3+CD4+ and CD3+CD8+ T cells, respectively, by immunomagnetic separation. Interferon gamma positive T cells have been further expanded in vitro from 0.54x106 ± 0.05x106 to 214.00x106 ± 103.46x106 within 4 weeks. A specific cytotoxicity has been tested after expansion. The killing of myeloma cells by expanded IFN g+ T cells reached 68.1±14.2%, while interferon gamma negative fraction killed only 0.8±0.3% of myeloma cells. As another control, killing of third-party PBMC by expanded interferon gamma positive T cells was 6.9±2.5%. Similar observations were made in MM patients and will be presented at the meeting.These data demonstrate a specific cytotoxic effect of expanded interferon gamma positive T cells against myeloma cell line ARH 77 and open the possibility for clinical use of tumor-specific T cells in MM.

Low Incidence of Acute Rejection after Living-Donor Liver Transplantation: Immunologic Analyses by Mixed Lymphocyte Reaction using a Carboxyfluorescein Diacetate Succinimidyl Ester Labeling Technique

To monitor antidonor alloreactivity for accurate diagnosis of acute rejection after living-donor liver transplantation (LDLT), we used a mixed lymphocyte reaction (MLR) assay using an intracellular fluorescent dye carboxyfluorescein diacetate succimidyl ester (CFSE)-labeling technique (CFSE-MLR) in 29 consecutive patients who underwent adult-to-adult LDLT. For patients who developed moderate or severe disorders in liver function, CFSE-MLR was performed together with needle biopsy of the liver allografts immediately after liver dysfunction had occurred. CFSE-labeled peripheral blood mononuclear cells (PBMC) from recipients and irradiated autologous, donor, or third-party PBMC were cultured, and then proliferation and CD25 expression in each of the CD4+ and CD8+ T cell subsets were analyzed by flow cytometry. Twelve (41.4%) of the 29 patients developed moderate or severe disorders in liver function within 6 months after LDLT. Eight of the 12 patients (overall incidence of 27.6%) suffering from liver function disorder were diagnosed on the basis of liver biopsy results as having mild or moderate acute rejection. However, only 4 of the 12 patients (overall incidence of 13.8%) showed remarkable proliferation of CD8+ T cells in association with CD25 expression on antidonor CFSE-MLR. The other eight patients were eventually diagnosed as having recurrence of original hepatitis, drug-induced hepatotoxicity, or congestion of the anterior segment of the liver allograft by further extensive examinations or in retrospect. The results of CFSE-MLR assays, which could be used for rigorously monitoring rejection, provided evidence of low incidence of acute rejection after LDLT.

Granzyme B ELISPOT Assay Determines the Cytotoxic T Lymphocyte Precursor Frequency After HLA-Identical Living-Related Kidney Transplantation

A major goal in organ transplantation is to define the optimal immunosuppressive dose. Recently, we demonstrated that the frequency of cytotoxic T lymphocytes (CTLpf) identifies patients in whom the immunosuppressive load can be safely reduced. However, in peripheral blood mononuclear cells (PBMC) from HLA-identical living-related kidney transplant patients, no donor-specific CTLpf can be measured. The determination of the functional activity of cytotoxic T lymphocytes (CTLs) could be an alternative method for the CTLpf. Granzyme B (GrB) is present in the granules of CTLs and is involved in the direct lethal hit of donor target cells. Therefore, we wondered whether the GrB ELISPOT assay is an alternative method to determine the activity of CTLs after HLA-identical living-related kidney transplantation. We measured the number of GrB producing cells (pc) against donor PBMC and third-party PBMC in PBMC from HLA-identical patients who were reduced in their immunosuppression from 100% to 50% azathioprine with 5 to 10 mg/day prednisone. We found low numbers of GrB pc before reduction of immunosuppression, as only 20% of the patients' PBMC responded to donor cells, whereas 57% of the patients' PBMC responded to donor cells after reduction of immunosuppression. After third-party stimulation, the number of GrB pc increased after tapering the immunosuppressive load ( P = .03). Our results demonstrate that the GrB ELISPOT assay might be used as an alternative for the CTLpf after HLA-identical living-related kidney transplantation.