摘要:

Antigen-specific CD8-expressing T cells play a crucial role in the host's defense against viral disease and malignancy. Epitope-specific CD8+T cell responses to malignant and viral disease can be accurately measured using tetramers (tHLA) of HLA class I molecules loaded with antigenic peptides. In addition, tHLA have been used to evaluate immune responses to antigen-specific immunization. tHLA bind specifically to complementary T-cell receptor (TCR) structures on the surface of T cells expressing the CD8 coreceptor. Surprisingly, however, CD8−cells binding tHLA are often observed. This study uses four-color flow cytometry to show that HLA-A*0201-tHLA-stained CD8−cells can be divided into two subsets: 87% represent B-lymphocytes (CD19+, CD45RA+, HLA-DR+, and CD20+), and 13% represent T-helper cells (CD3+, CD4+, CD45RA+, and CD27+). This phenomenon is not HLA-restricted because it could be observed even in peripheral blood mononuclear cells (PBMC) from a non HLA-A*0201-expressing healthy donor. In addition, no T-cell receptor was detected on the B-lymphocytes. Retrospective enumeration of vaccine-induced CD8−tHLA+cells in 243 PBMC samples from 36 patients with melanoma undergoing peptide vaccination revealed that tHLA staining is not dependent on immunization status or the presence of CD8+tHLA+T cells. These findings, suggest that the nonspecific binding of tHLA to non-TCR-expressing T cells requires a careful interpretation of results and further steps in preparation of sample for tHLA-based sorting of epitope specific T cells.

ISSN:1524-9557    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

T lymphocytes used for adoptive immunotherapy are often cultured before transfer to generate sufficient amounts of effector cells with desired specificity. Modification of lymphocytes induced by in vitro activation and expansion may influence their potential effector capacity by altering the survival and trafficking patterns after transfer. In this report, the authors show that the culture period of T cells after ConA/IL-2 stimulation strongly influences the retention and tissue distribution of these cells after infusion into syngeneic C57BL/6 mice. Infused labeled cells that have been cultured for 3 days remained in the peripheral blood and organs in at least a ten-fold higher number than cells cultured for 8 days. In addition, cells cultured for 3 days preferentially migrate to lungs and liver shortly after infusion and subsequently to lymph nodes and spleen. Cells cultured for 8 days preferentially migrate to liver and can be hardly detected in lymph nodes. In contrast, labeled cells cultured for 3 days are predominantly present in lymph nodes starting from day 8 until day 28. We showed that accurate monitoring of transferred cells is feasible, which may contribute to understanding response to adoptive immunotherapy.

ISSN:1524-9557    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

A rare type of antibody that spontaneously binds to each self (homodimerizes) has been described. This self-binding (autophilic) antibody provides stronger protection against bacterial infection than a non self-binding antibody with identical specificity and affinity due to increase of polymeric avidity. A peptide derived from the self-binding domain of the autophilic antibody was crosslinked to the Fc carbohydrate of two monoclonal antibodies specific for the B-cell receptor (BCR) of a murine and a human B-cell tumor. Peptide-crosslinked antibodies bind to themselves on solid phase ELISA as homodimer and establish in solution a monomer-dimer equilibrium. Autophilic antibodies bind to their respective tumor target cells with increased efficiency as determined by FACS analysis. They also induce twice the amount of apoptosis of target tumor cells than the control antibodies. Furthermore, the modified antibodies inhibit tumor growth in culture more efficiently than the control antibodies. Criss-cross protocols in FACS, apoptosis, and growth inhibition indicate the specificity of targeting the BCR with autophilic antitumor antibodies. The chemical approach of increasing the binding of antibodies without creating chemically crosslinked dimers mimics naturally occurring autophilic antibodies and represents a simple and attractive alternative to chemical dimerizing and antibody engineering techniques for improving their antitumor effect. Furthermore, these results provide a guide to incorporate the self-binding peptide into the structure of antibodies using modeling and molecular crafting techniques.

ISSN:1524-9557    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The benefit of immunochemotherapy employing a streptococcal preparation, OK-432 (Picibanil), in patients with curatively resected gastric cancer was reassessed by meta-analysis of data from 1,522 patients enrolled in six clinical trials with central randomization. All six trials began between 1985 and 1993, and patients were followed-up for at least 3 years after surgery and enrollment of the last patient. In these trials, standard chemotherapy was compared with the same chemotherapy plus OK-432. The endpoint was overall survival and intent-to-treat analysis was done without patient exclusion. Data were analyzed using the Mantel-Haenszel method. The 3-year survival rate for all eligible patients in the six trials was 67.5% in the immunochemotherapy group versus 62.6% in the chemotherapy group. The 3-year overall survival odds ratio was 0.81 (95% confidence interval: 0.65–0.99). The treatment effect was shown to be statistically significant (p = 0.044). The results of this meta-analysis suggest that immunochemotherapy after surgery with OK-432 can improve the survival of patients with curatively resected gastric cancer.

ISSN:1524-9557    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Echinacea extracts are widely used in European countries and in the United States as “immune-stimulating” agents. Even though the evidence to stimulate certain components of the nonspecific immune system (phagocytosis, macrophages, and production of cytokines) stems from in vitro experiments or studies after parenteral application, the commercially available Echinacea preparations used as drugs or supplements are for oral use. The aim of the study was to determine whether phagocytic activity and production of cytokines is stimulated by oral application of a commercially available Echinacea preparation. Forty healthy male volunteers (ages 20–40 years) participated in the study. They received either a freshly expressed juice of Echinacea purpurea herbs or placebo juice using a double-blind placebo-controlled crossover design with two treatment periods of 14 days and a wash-out period of 4 weeks in between. Endpoints for immune stimulation: phagocytic activity of polymorphonuclear leukocytes and monocytes measured by flowcytometry, production of tumor necrosis factor alpha (TNF)-&agr; and Interleukin (IL)-1&bgr; by LPS-stimulated blood monocytes. Echinacea purpurea herbs did neither enhance phagocytic activity of polymorphonuclear leukocytes nor that of monocytes when compared with placebo. Echinacea purpurea herbs did not influence the production TNF-&agr; and IL-1&bgr; by LPS-stimulated monocytes. Unexpectedly, Echinacea purpurea herbs decreased serum ferritin concentration (p = 0.0005). All other laboratory and safety data remained unchanged. The “immune stimulation” by Echinacea purpurea observed in vitro and after parenteral administration are not confirmed in healthy humans after oral intake. Other immunomodulatory effects may explain the benefits of Echinacea preparations in reducing duration and severity of upper-respiratory tract infections found in randomized, double-blind clinical trials.

ISSN:1524-9557    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Malignant melanoma has been shown to be susceptible to T cell-mediated immunity and, therefore, is a candidate for vaccination approaches. Clinical trials using dendritic cells (DC) loaded with peptides corresponding to tumor antigens are ongoing in several institutions, and some promising results have already been published. However, every single peptide-based vaccine can only be used in a patient with a given single HLA type, and this strategy is not appropriate for patients with rare HLA types or with tumors without defined antigens. A clinical pilot study in patients with disseminated melanoma refractory to standard therapy was initiated using a different approach. The authors generated autologous monocyte-derived DC and fused these DC with gamma-irradiated primary autologous tumor cells by incubation in polyethylene glycol. In previous experiments, the authors had shown that these fused cell products are potent inducers of a T-cell response in a mixed lymphocyte tumor cell culture. Seventeen patients were immunized with the cell product by s.c. injection in monthly intervals without any serious side effects. Of these patients, one had a partial response with decrease in size of all evaluable tumor manifestations. In one patient, some of the metastases were regressing despite an overall progressive disease, and one patient achieved disease stabilization for six months. In the responding patient, in parallel to tumor regression, circumscript hair depigmentation occurred. These data show, that a hybrid vaccine of DC and tumor cells can be safely applied and can induce tumor regressions, however, the clinical efficacy of the approach in its present form is insufficient.

ISSN:1524-9557    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Dendritic cells (DC) are the professional antigen presenting cells of the immune system. Therefore, several clinical studies have been initiated in which tumor antigen-loaded DC are used as a vaccine to boost an immune response against malignant tumors in patients with cancer. A prerequisite for DC used in these vaccination studies is not only that they are grown under “Good Manufacturing Practice” but equally important that they retain their functional properties. In an extensive study, various conditions were tested to optimize the maturation and yield of DC grown for clinical use. DC grown in XVIVO-15 medium supplemented with 5% HS yielded the best results, morphologically and phenotypically. Mature DC expressed significant amounts of mature DC markers (CD83) and the costimulatory molecules CD80 and CD86. It was shown that mature and immature DC can be frozen and retain their phenotype and function after thawing. These clinical grade DC secreted high levels of the chemokines dendritic cell chemokine 1 (DC-CK1), interleukin-8 (IL-8), macrophage-derived chemokine (MDC), and thymus and activation-regulated chemokine (TARC). This implicates that these DC can attract naïve T and B cells as well as natural killer cells and memory T cells. Finally, to test their migratory capacity in vivo,111In-labeled DC were injected into tumor-free lymph nodes of patients with melanoma. Autoradiographic analysis of the dissected lymph nodes indicated that these DC could migrate into the T cell area of adjacent lymph nodes. In conclusion, a culture procedure was established to generate large numbers of monocyte-derived immature and mature DC that retain their morphologic, phenotypic, and functional characteristics in vitro and can be visualized in situ.

ISSN:1524-9557    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Cyclophilin B (CypB) possesses two antigenic epitopes (CypB84–92and CypB91–99) recognized by HLA-A24-restricted and tumor-specific cytotoxic T lymphocytes (CTLs). To determine the safety of CypB-derived peptides and its ability to generate antitumor immune responses, patients with advanced lung cancer received subcutaneous vaccinations of these peptides or their modified peptides. All 16 patients were vaccinated with CypB91–99or its modified peptide, whereas only two patients were vaccinated with the modified CypB84–92, as immediate-type hypersensitivity to CypB84–92or its modified peptide was observed in the remaining patients. No severe adverse events were associated with the vaccination. No significant increase in cellular responses to either peptides or tumor cells was observed in the postvaccination PBMCs by the conventional CTL assays in any patients tested. These results suggest that the vaccination of CypB91–99peptide was safe, but failed to induce objective immune responses at this regimen.

ISSN:1524-9557    

出版商:OVID    

年代:2002

数据来源: OVID