Monika Lindemann

CD4 + CD25 + FoxP3 + T lymphocytes fail to suppress myelin basic protein-induced proliferation in patients with multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disorder directed against self antigens of the central nervous system. CD4(+)CD25(+)FoxP3(+) regulatory T cell (T(reg)) mediated suppression is an essential mechanism of self-tolerance. We studied whether changes in the suppressive function of a mixture of CD25(high) and CD25(intemediate) expressing T(reg) cells in myelin basic protein (MBP)-induced proliferation occurred in untreated MS patients. Suppression of MBP-induced proliferation was observed in 13 out of 29 (45%) MS patients; this was significantly (p<0.05) less compared with 17 out of 19 (89%) healthy individuals. Relative T(reg) counts was significantly increased in MS patients (mean+/-S.D.; 20+/-8%) compared with healthy individuals (15+/-5%). These findings suggest that impaired T(reg) function may be involved in pathogenesis of MS.

The G protein β3 subunit 825T allele is a genetic marker for enhanced T cell response

The G protein β3 subunit (GNB3) 825T allele is predictive of enhanced Gi protein activation. Studying the influence of C825T allele status on cellular in vitro immune responses towards recall antigens and interleukin‐2 stimulation we observed a 2–4‐fold, significantly increased proliferation in homozygous 825T (TT) vs. C825 allele (CC) carriers. Furthermore, lymphocyte chemotaxis and CD4+ T cell counts of individuals with TT+TC genotypes were significantly enhanced compared to the CC genotype. In summary, it appears that C825T allele status is highly predictive of immunocompetence and could be a candidate gene in disorders associated with inadequate immune response.

Immune parameters in multiple myeloma patients: influence of treatment and correlation with opportunistic infections.

The present study evaluated cellular and humoral immune parameters in myeloma patients, focusing on the effect of treatment and the risk of opportunistic infections. Peripheral blood lymphocyte subsets and serum levels of nonmyeloma immunoglobulins (Ig) were analysed in 480 blood samples from 77 myeloma patients. Untreated myeloma patients exhibited significantly reduced CD4+/45RO+, CD19+, CD3+/HLA-DR+, and natural killer (NK) cells, as well as nonmyeloma IgA, IgG and IgM. Conventional-dose chemotherapy resulted in significantly reduced CD4+ and even further decline of CD4+/CD45RO+ and CD19+ cells, most notably in relapsed patients. Additional thalidomide treatment had no significant effects on these parameters. Following high-dose chemotherapy (HD-CTX), prolonged immunosuppression was observed. Although CD8+, NK, CD19+ and CD+/CD45RO+ cells recovered to normal values within 60, 90, 360 and 720 days, respectively, CD4+ counts remained reduced even thereafter. Nine opportunistic infections were observed, including five cytomegalovirus (CMV) diseases, one Pneumocystis carinii pneumonia (PCP) and three varicella zoster virus infections with CMV diseases and PCP occurring exclusively after HD-CTX. Opportunistic infections were correlated with severely reduced CD4+, as well as CD4+/CD45RO+ and CD19+ counts. Thus, myeloma patients display cellular and humoral immunodeficiencies, which increase following conventional as well as HD-CTX, and constitute an important predisposing factor for opportunistic infections.

Impact of localized radiotherapy on blood immune cells counts and function in humans.

Immune cells subsets were prospectively analyzed after localized radiotherapy (LRT). LRT reduced the levels of all lymphocyte subsets, with B-cells and naive T-cells being most sensitive. Lymphocyte function was suppressed, but still within the normal range. Rapid recovery of cytotoxic T-cells/natural killer cells after LRT and the functional suppression within normal levels explains the low incidence of infections after LRT.

Transfer of humoral and cellular hepatitis B immunity by allogeneic hematopoietic cell transplantation.

Background. Previous data indicate that a transfer of specific humoral and cellular immunity by way of allogeneic hematopoietic cell transplantation (HCT) should, in principle, be possible. Methods. In the HCT setting with a follow-up of up to 55 months, we studied the transfer of hepatitis B virus (HBV) specific immunity from electively immunized donors into HLA compatible recipients suffering from chronic myeloid leukemia (CML). After excluding preexisting HBV specific immunity in donor–recipient pairs, 27 prospective donors were vaccinated against HBV. In addition, on an average of 22 months postHCT, 8 of the 19 recipients were immunized once for HBV. Results. Donor vaccination resulted in detectable hepatitis B surface (HBs) antibodies in 85% of donors and specific cellular in vitro responses in 77%. Two weeks postHCT, 86 and 67% of the recipients displayed positive humoral and cellular HBV reactions, respectively, which then decreased. Afterwards, HBV immunity reappeared in 83% of the recipients without revaccination. Following a single vaccination in recipients, seven of eight displayed a typical memory response. An HBV specific response was already detectable 1 week after vaccination, approximately 1,300-fold (humoral) and 60-fold (cellular) higher than observed in the corresponding donors after a single immunization. Conclusions. The “spontaneous” recurrence of HBV immunity and the memory response in recipients give evidence for an elective immune transfer (e.g., for viral antigens) by way of allogeneic HCT.

Induction of a robust T- and B-cell immune response in non- and low-responders to conventional vaccination against hepatitis B by using a third generation PreS/S vaccine

Non-responsiveness to conventional hepatitis B vaccines in individuals at high risk of exposure to hepatitis B virus (HBV) is an important public health problem and of particular relevance in health care providers. Yeast-derived conventional HBsAg vaccines fail to induce protective antibody titers in up to 10% of immune competent vaccinees. Therefore, a third generation HBV vaccine, Sci-B-Vac™, was developed which contains in addition to the small S antigen the PreS1 and PreS2 antigens. This vaccine proved to induce a highly potent cellular and humoral immune response in healthy individuals as well as protective antibody levels in non- and low-responders to conventional HBV vaccines. The aim of the study was to examine whether Sci-B-Vac™ triggers cellular and humoral immunity in individuals who failed immunization with conventional vaccines. We immunized 21 volunteers (15 non- and 6 low-responders) according to the standard vaccination schedule (0, 4 and 24 weeks), determined the cellular immunity by proliferation assay and interferon (IFN)-γ ELISpot and measured the anti-HBs antibody titers prior to each vaccination and four weeks after the third vaccine dose. Following three vaccinations, PreS/S-specific T-cell proliferation was detected in 8 out of 15 non-responders and 5 out of 6 low-responders. Specific IFN-γ responses were measured in 2 out of 15 non-responders and 4 out of 6 low-responders. All but one (20/21) study participants developed anti-HBs titers ≥10IU/l after three vaccinations. Anti-HBs ≥100IU/L were detected in 12 out of 15 non-responders and in 6 out of 6 low-responders. Anti-HBs ≥10IU/l and <100IU/l were found in 2 non-responders. These results indicate that Sci-B-Vac™ induces cellular immunity as well as protective anti-HBs antibody titers in non- and low-responders. In conclusion, these results confirm that Sci-B-Vac™ should be administered to non-responders to conventional HBV vaccines and patients with impaired immune function.

Adoptive immune transfer of hepatitis B virus specific immunity from immunized living liver donors to liver recipients.

Background. Liver transplantation is often the ultimate option of therapy for chronically hepatitis B virus (HBV) infected patients. Prevention of reinfection is therapy intensive and cost-effective. Adoptive transfer of HBV-specific immunity with the liver from an immune living liver donor (LLD) could be a new approach to prevent reinfection. Methods. Forty-six potential LLDs were vaccinated against HBV. Humoral (antibodies to hepatitis B virus surface antigen [anti-HBs]-titer) and cellular (IFN-γ-ELISpot and proliferation-assay) immune responses were examined in donors after immunization and in recipients before and after transplantation. Results. Anti-HBs-titers of up to 50,000 IU/L were detected in LLDs. Fourteen recipients received livers from these donors. We detected humoral immunity in one HBV-naïve recipient and in one chronically HBV-infected recipient after transplantation. A transfer of cellular immunity (SI>3) was seen in three recipients. These patients received livers from donors with high anti-HBs-titers of more than 9000 IU/L. Cellular immunity was also detected in the corresponding donors (SI >3 and spots >22). Conclusions. Our study demonstrates that HBV-specific humoral and cellular immunity can be transferred by liver transplantation after vaccination of the donors. The transfer of B-cell and T-cell immunity correlates with the magnitude of immune responses in the donor.

Genetic, immunological and clinical risk factors for biliary strictures following liver transplantation

Biliary strictures after liver transplantation (LT) are a major cause of morbidity and reduced graft survival.

Donor-Specific Anti-HLA Antibodies and Endothelial C4d Deposition-Association With Chronic Liver Allograft Failure.

Background The significance of humoral immune response for allograft survival after liver transplantation (LT) is still a matter of debate. The aim of this cross-sectional study was to assess immunological and clinical factors associated with advanced fibrosis (F3-F4) and chronic graft failure in LT recipients. Methods Serum samples from 174 patients prospectively enrolled and followed up for 12 months were tested for anti-HLA antibodies and compared against donor HLA types. Immunohistochemical C4d staining was performed on formalin-fixed, paraffin-embedded liver tissue. Results Mean time period from LT to enrollment was 66.9 ± 51.9 months. Independent predictive factors for graft failure included donor-positive cytomegalovirus serostatus (P = 0.02), donor-specific antibodies (DSA) against HLA class II (P = 0.03), donor age (P = 0.01), hepatitis C virus allograft reinfection (P = 0.0008), and biliary complications (P = 0.003). HLA class II DSA and HLA class I antibody positivity, hepatitis C virus reinfection, and mycophenolate mofetil-free regimens were significant risk factors for advanced fibrosis after LT. There was a significant association between C4d deposition on allograft endothelial cells and presence of class II DSA (P < 0.0001). Patients with C4d deposits had a 4.3 times higher risk of graft failure than those with negative staining and a significantly lower median time to graft failure (94.6 months [range, 3.6-158.9 months] vs 176.4 months [range, 9.4-217.8 months], P < 0.0001). Conclusions Screening for HLA DSA might be useful for early identification of LT recipients at increased risk of graft failure who could benefit from closer surveillance and tailored immunosuppressive regimens.

Mycophenolic Acid Impedes the Antigen Presenting and Lymph Node Homing Capacities of Human Blood Myeloid Dendritic Cells

Background. Mycophenolic acid (MPA) is the pharmacologically active compound of the immunosuppressive drug mycophenolate mofetil. Dendritic cells (DC) are the key to initiating and priming the adaptive immune response leading to allograft rejection. We investigated the effects of MPA on human blood myeloid DC (MDC) homeostasis with a particular emphasis on their trafficking properties. Methods. Isolated peripheral blood mononuclear cells from healthy donors were cultured with MPA for 48 hr without the addition of exogenous growth factors. Flow cytometry was used for phenotypic and functional analysis of MDC within the cultured peripheral blood mononuclear cells population. Freshly isolated MDC were used for assessment of endocytotic and allostimulatory properties. Results. Exposure to MPA decreased the expression of CC chemokine receptor (CCR)7 and increased the expression of CCR1 in MDC. In line with their CCR expression profile, MPA-treated MDC showed an enhanced migration toward inflammatory chemokines, whereas their migratory response toward lymph node chemokines decreased. MDC cultured with MPA exhibited an immature phenotype with higher endocytotic capacity, an impaired activation in response to toll-like receptor 3 ligation and loss of capacity to stimulate allogenic T cells in mixed lymphocyte reactions. Conclusion. MPA interferes with the initiation of acquired immunity and thus may promote allograft tolerance.