Mechanisms of action of regulatory T cells specific for paternal antigens during pregnancy

OBJECTIVE: To investigate whether pregnancy-induced regulatory T cells are generated specifically for paternal antigens or expanded by hormonal changes and to study regulatory T cell-related mechanisms during pregnancy. METHODS: We used murine models of normal, abortion-prone, and pseudopregnancy to characterize regulatory T cells and hormones by methods such as flow cytometry, molecular biology techniques, and chemiluminescence. Antigen specificity was studied in experiments in which animals were vaccinated with paternal antigens or adoptively transferred with regulatory T cells. To analyze regulatory T cell-mediated mechanisms, we used neutralizing antibodies against IL-10 or TGF-beta. RESULTS: Regulatory T cells are activated by male antigens, and minor antigens are protected by linked immunosuppression. Our data exclude the possibility that regulatory T cell expansion during pregnancy is exclusively driven by hormonal changes. An increase in systemic regulatory T cell levels in pseudopregnant females after mating with vasectomized males but not after pseudopregnancy induced mechanically confirms generation of regulatory T cells specific for paternal antigens. As for the mechanisms, neutralizing IL-10 abrogates the protective effect of regulatory T cells, whereas blockage of TGF-beta does not provide the same effect. CONCLUSION: Our data confirm that regulatory T cells act in an antigen-specific manner during pregnancy and strongly suggest that IL-10 is involved in regulatory T cell-mediated protection of the fetus. These data contribute to the knowledge of the basic mechanisms regulating immune tolerance during pregnancy, a major biologic question with important medical implications. LEVEL OF EVIDENCE: II.     

Salivary gland carcinomas Part II. Diagnosis and therapy

Salivary gland carcinomas comprise a rare group of malignant tumors which are difficult to diagnose and treat due to their histopathologic diversity, variable clinical course and anatomic location, particularly with respect to the facial nerve. The present paper summarizes important features of these tumors, including recent advances in their management, i.e., diagnosis, surgery of the primary tumor, neck dissection, radiation therapy, and updates risk factors, criteria of malignancy, and prognostic variables, taking into account the relevant literature. Additionally, the present paper highlights briefly the survival rates of patients suffering from salivary gland carcinomas. The present overview is divided into two parts: the first is focused on epidemiology, etiology, criteria of malignancy, prognostic factors, and tumor classification, while part II discusses the diagnosis and therapy of salivary gland carcinomas.     

Creation of immune 'stealth' genes for gene therapy through fusion with the Gly-Ala repeat of EBNA-1

A major obstacle in gene-therapy protocols is T-cell-mediated destruction of transgene-expressing cells. Therefore new approaches are needed to prevent rapid clearance of transduced cells. We exploited the Gly-Ala repeat (GAr) domain of the Epstein-Barr virus nuclear antigen-1, since the GAr prevents cytotoxic T-lymphocyte-epitope generation. Here we show that three different enzymes (viz. the E. coli LacZ gene encoded beta-galactosidase, firefly luciferase, and HSV1 thymidine kinase) fused with the GAr retained their function. Moreover, linking GAr with beta-galactosidase successfully prevented recognition of GAr-LacZ-expressing cells by beta-galactosidase-specific CTL. Nonetheless, vaccination with a GAr-LacZ adenovirus or with an allogeneic cell line expressing GAr-LacZ resulted in the induction of beta-gal-specific CTL. This demonstrates that the GAr domain does not inhibit cross presentation of antigens, but only affects breakdown of endogenously synthesized proteins. These data demonstrate how the GAr domain can be exploited to create immuno'stealth' genes by hiding transgene products from CTL-mediated immune attack.     

Secretion of tumor-promoting and immune suppressive cytokines by cell lines of head and neck squamous cell carcinoma

BACKGROUND: Cytokine profiles of permanent cell lines of head and neck squamous cell carcinoma (HNSCC) were analyzed to define the cytokine levels secreted in the absence of immune cells. MATERIALS AND METHODS: Cytokine profiles of IL-4, IL-6, IL-8 and IL-10 were analyzed in the supematants of 4 different permanent HNSCC cell lines using the Bio-Plex human cytokine assay system. RESULTS: In HNSCC, IL-6 and IL-8 are involved in oncogenic processes, while IL-4 and IL-10 suppress proper immune responses in the tumor microenvironment. Our data indicate that, in the absence of tumor-infiltrating immune cells, HNSCC secretes high levels of the proto-oncogenic cytokines IL-6 and IL-8, but no significant levels of the immune suppressors IL-4 and IL-10. CONCLUSION: The data strongly suggest that the intercellular crosstalk between cells of HNSCC and tumor-infiltrating immune cells in vivo is required to stimulate an increased production of immune suppressive mediators in head and neck cancer.     

Transthoracic fine-needle aspiration cytology. Analysis of 82 patients with detailed verification criteria and evaluation of false-negative cases

The authors herein report a series of transthoracic fine-needle aspiration cytology studies performed over a ten-year period at a medical center. The verification criteria they utilized for "positive" and " nonpositive " results are unique to the TFNA literature, as is the authors' detailed analysis of false-negative cases. The authors' statistical findings included specificity, 100%; sensitivity, 79.0%; and overall accuracy, 83.0%. Eleven of 13 false-negative studies (84.6%) were consequent to sampling error; the remaining two cases (both "suspects") were the result of cytopathologist judgment error. In those patients with tissue corroboration of their lung disease, the authors obtained a 93.8% concordance rate between cytology and histology results. They conclude that uniform verification criteria, as well as careful analysis of "suspects" and false negatives, can lead to better patient care through improved quality control.     

Identification of CD11c+ myeloid dentritic cells in adenoids and in nasal mucosa of patients with and without allergies

BACKGROUND: Dendritic cells form a link between innate and acquired immunity. They are capable to detect pathogens based on the recognition of pathogen-associated microbial molecules and trigger the appropriate type of immune responses. In humans, three major subsets of dendritic cells can be distinguished, Langerhans cells of the skin, myeloid DC (MDC) and plasmacytoid DC (PDC). It was reported that PDC infiltrate nasal mucosa in allergen-induced rhinitis. Information about the role of MDC in nasal mucosa and the corresponding mucosa-associated lymphoid tissue, the nasopharyngeal adenoids, is limited. PATIENTS AND METHODS:: Here we examined the presence of MDC in adenoids and in nasal mucosa of healthy individuals (n = 9) and in patients with allergic rhinitis. MDC were detected by flow cytometry by positive staining for MHC II and CD11c and the lack of lineage markers. Dead cells were excluded from analysis. RESULTS: In adenoids, 0.4 % of all cells were MDC. Considerable numbers of MDC could also be detected in nasal mucosa. No difference was found between healthy individuals and patients with allergies (0.3 % vs. 0.45 % MDC; p = 0.12). Interestingly, MDC were absent in patients who received treatment with glucocorticoids, while very high numbers of MDC were found in patients who recently had upper respiratory tract infections. CONCLUSION: Our results demonstrate for the first time the presence of MDC in nasal mucosa. MDC numbers were similar in healthy individuals and in patients with allergy. This study forms the basis for examining the role of MDC in the pathogenesis of allergic rhinitis, and for the modulation of MDC functional activity with microbial molecules such as CpG oligonucleotides.     

TNFalpha contributes to the antitumor activity of a bispecific, trifunctional antibody

Immunological cancer therapies focus on the activation of immune effector cells yielding a specific antitumor activity. Disseminated tumor cells are regarded as the origin of metastases and consequently their elimination is the central objective of adjuvant immune therapies. The use of bispecific antibodies is an approach that is regarded as promising in order to fight those disseminated tumor cells. Unfortunately, the efficiency of these antibodies is limited by the fact that they usually activate a single class of effector cell, thus not yielding optimal immune response. In addition, tumor cells may down-regulate the antibody's target molecule and escape recognition. We have recently described results with an intact bispecific molecule, BiUII, that represents a new class of intact antibodies. These antibodies, termed "triomab", provide an excellent antitumor activity in vitro, a fact that most probably is attributable to the simultaneous activation of different classes of immune effector cells. We have now investigated this antitumor activity in more detail and demonstrate here that at least a dual mechanism accounts for triomab-mediated killing of tumor cells: besides direct cell-mediated killing, triomab induces the production of TNFalpha in PBMCs at concentrations that induce apoptosis in target cells. This bystander effect may be of special interest for the clinical application of triomab in terms of killing of target antigen-negative tumor cells.