Local reactions during allergen immunotherapy do not require dose adjustment

BACKGROUND: The recent World Health Organization position paper on allergen immunotherapy states that local reactions to immunotherapy are not predictive of subsequent systemic reactions. Nevertheless, in clinical practice dose adjustment after local reactions continues to be recommended, presumably in an effort to prevent future systemic reactions. OBJECTIVE: We sought to determine whether dose adjustment versus no adjustment for local reactions during allergen immunotherapy influences the occurrence of subsequent systemic reactions. METHODS: In a single-site allergy clinic before October 1, 1997, local reactions after allergen vaccine injection resulted in adjustment of the subsequent dose. After October 1, 1997, no dose adjustments were made for immediate and late local reactions. For the same 9-month period before and after the change in local reaction dose-adjustment policy, systemic reaction rates were compared retrospectively. For individuals experiencing a systemic reaction, local reaction rates and local reactions immediately preceding a systemic reaction were also compared before and after the policy change. RESULTS: Comparing the 9-month period (October 1996-June 1997) preceding the policy change and the 9 months (October 1997-June 1998) after the change in policy, the systemic reaction rates (0.80% and 1.01%, respectively) were not statistically different (P =.24). Among those experiencing a systemic reaction, the rate of local reactions was unchanged (7.3% and 4.7%, respectively; P =.07), and the rate of local reactions immediately preceding a systemic reaction did not increase (18.8% and 10.5%, respectively; P =.37). The sensitivity of a local reaction predicting a systemic reaction at the next immunotherapy dose was 15%. CONCLUSIONS: A local reaction is a very insensitive predictor for a subsequent systemic reaction at the next allergen vaccine dose. Dose adjustment for most local reactions is unnecessary and may delay therapy, increase costs, and put the patient at increased risk of dose administration errors.     

Harnessing dendritic cells for immunotherapy

Dendritic cells (DC) are the antigen presenting cells that initiate and direct adaptive immune responses, capable of inducing protective adaptive immune responses and tolerance. They sample their surroundings, internalizing, processing and presenting antigens to T cells. They distinguish between self and foreign antigens with a wide array of microbial sensors, and induce immunity when antigen is captured in the presence of microbial products or inflammatory stimuli, but tolerance in the absence of these signals. However, not all DCs are identical. There are distinct DC subsets spread throughout the body, and although they share common features, they also have specialized functions. As a consequence, the outcome of the immune response is determined by the context in which the antigen is acquired, and also by the DC subset(s) involved. Here we discuss the features of the DC subsets, their handling of antigens for MHCI- and MHCII-restricted presentation, how their functions are regulated by foreign and endogenous signals, the consequences on the type of immune response induced, and how they provide insights on the design of immunotherapy.     

Loading of dendritic cells for immunotherapy

Dendritic cell therapy has been optimized a lot aiming to induce a strong and broad immune response in terms of the recognized epitopes by both CD8⁺ and CD4⁺ T cells and the use of the patients' complete unique set of HLA molecules. We here give an overview of our approach for antigen loading and maturation of dendritic cells and describe the consequences to evaluate the immune response after treatment as well as the Brussels experience in clinical trials.     

Genetically modified dendritic cells for cancer immunotherapy

The ability to grow and differentiate dendritic cells (DC) ex vivo has allowed their genetic manipulation to enhance immune activation against tumor antigens. Gene engineering of DC can be achieved with a variety of physical methods and using different viral vectors. RNA or DNA transfection, either alone (naked), coated with liposomes or using electroporation or gene guns leads to T cell activation while transgene expression is frequently undetectable. Adenoviral and retroviral vectors have proven to be highly efficient in DC genetic modification, and have been widely used in preclinical models. Other vectors like lentivirus, poxvirus, herpes virus and adeno-associated virus (AAV) can also lead to foreign transgene expression in DC leading to immune cell activation. DC have been genetically engineered to provide constitutive and high level of tumor antigen expression or to introduce genes that further enhance their immune stimulatory ability. The promising results from preclinical animal models and from in vitro human immune cell culture systems have provided a strong rationale to initiate pilot clinical trials. Recently published or communicated clinical experiences and ongoing trials have used defined tumor antigen RNA transfection for prostate carcinoma and melanoma, liposome-encoated DNA transfection for breast or pancreatic cancer, adenoviral vector tumor antigen gene modification for melanoma and small cell lung cancer, and poxvirus-mediated expression of costimulatory molecules for colon carcinoma. These preliminary experiences suggest that genetically modified DC can safely induce T cell responses but few clinical responses.     

Targeting dendritic cells in allergen immunotherapy

Allergen immunotherapy is a well-established strategy for treating allergic diseases with the goal of inducing allergen-specific tolerance. Identified mechanisms contributing to the therapeutic effect of immunotherapy include a shift of T helper 2 (Th2)-type immune responses to a modified Th2 immune response, a change of the balance of IgE-producing B cells to the production of IgG subtypes, in addition to increased IL-10 and TGF-beta secretion and activation of the suppressive functions of regulatory T-cells. Dendritic cells (DCs), which as outposts of the immune system are capable of T-cell priming through efficient allergen uptake by IgE receptors expressed on their cell surface. Most of the hypotheses concerning the function of DCs as facilitators of allergen-specific tolerance in allergen immunotherapy remain speculative. Therefore, studies must focus on the functional changes of DCs under immunotherapy to close the gap of knowledge about their exact role. These experimental data should help confirm the hypothesis of DCs as efficient silencers and potential target cells and take advantage of the bivalent character and tolerogenic properties of DCs.     

Interferon-γ- and interleukin-4-producing T cells can be primed on dendritic cells in vivo and do not require the presence of B cells

The antigen-presenting cell (APC) requirements for the in vivo induction of Th1-and Th2-type responses were investigated using a severe combined immunodeficiency (SCID)mouse chimera model. SCID mice adoptively transferred with either T cells [SCID(T)] or T + B cells [SCID(T + B)] and immunized with antigen in adjuvant were able to generate antigen-specific T cells which could produce both interferon (IFN)-γ and interleukin (IL)-4 upon in vitro restimulation. This suggests that B cell APC are not necessary for the priming of either IFN-γ- or IL-4-producing T cells in vivo. The ability of different APC to activate Th2-dependent effector mechanisms was also investigated. SCID(T) and SCID(T + B) mice were infected with the nematode parasite Nippostrongylus brasiliensis and analyzed for the development of IL-5-dependent peripheral blood eosinophilia. Following infection both SCID(T) and SCID(T + B) mice generated similar numbers of peripheral blood eosilnophils, suggesting that similar amounts of IL-5 had been produced. Therefore, B cell APC are also not required for the in vivo activation of Th2 cells to lymphokine production. To establish more precisely which APC prime T cells to produce IFN-γ and IL-4, normal mice were immunized by injection of syngeneic splenic dendritic cells which had been pulsed with antigen in vitro. T cells from these immunized mice were able to produce good IFN-γ and IL-4 responses upon in vitro restimulation with specific antigen; therefore, dendritic cells appear to be sufficient APC for the in vivo priming of both IFN-γ- and IL-4-producing T cells.     

Targeting dendritic cells to advance cross-presentation and vaccination outcomes

Dendritic cells (DCs) are a complex network of specialised antigen-presenting cells that are critical initiators of adaptive immunity. Targeting antigen directly to DCs in situ is a vaccination strategy that selectively delivers antigen to receptors expressed by DC subtypes. This approach exploits specific DC subset functions of antigen uptake and presentation. Here, we review DC-targeted vaccination strategies that are designed to elicit effective cross-presentation for CD8⁺ T cell immunity. In particular, we focus on approaches that exploit receptors highly expressed by mouse and human cDCs equipped with superior cross-presentation capacity. These receptors include DEC205, Clec9A and XCR1. Targeting DC receptors Clec12A, Clec4A4 and mannose receptor is also reviewed. Outcomes of DC-targeted vaccination in mouse models through to human clinical trials is discussed. This is a promising new vaccination approach capable of directly targeting the cross-presentation pathway for prevention and treatment of tumours and infectious diseases.     

AIRE is not essential for the induction of human tolerogenic dendritic cells

Loss-of-function mutations of the Autoimmune Regulator (AIRE) gene results in organ-specific autoimmunity and disease Autoimmune Polyendocrinopathy type 1 (APS1)/Autoimmune Polyendocrinopathy Candidiasis Ectodermal Dystrophy (APECED). The AIRE protein is crucial in the induction of central tolerance, promoting ectopic expression of tissue-specific antigens in medullary thymic epithelial cells and enabling removal of self-reactive T-cells. AIRE expression has recently been detected in myeloid dendritic cells (DC), suggesting AIRE may have a significant role in peripheral tolerance. DC stimulation of T-cells is critical in determining the initiation or lack of an immune response, depending on the pattern of costimulation and cytokine production by DCs, defining immunogenic/inflammatory (inflDC) and tolerogenic (tolDC) DC. In AIRE-deficient patients and healthy controls, we validated the role of AIRE in the generation and function of monocyte-derived inflDC and tolDCs by determining mRNA and protein expression of AIRE and comparing activation markers (HLA-DR/DP/DQ,CD83,CD86,CD274(PDL-1),TLR-2), cytokine production (IL-12p70,IL-10,IL-6,TNF-α,IFN-γ) and T-cell stimulatory capacity (mixed lymphocyte reaction) of AIRE+ and AIRE- DCs. We show for the first time that: (1) tolDCs from healthy individuals express AIRE; (2) AIRE expression is not significantly higher in tolDC compared to inflDC; (3) tolDC can be generated from APECED patient monocytes and (4) tolDCs lacking AIRE retain the same phenotype and reduced T-cell stimulatory function. Our findings suggest that AIRE does not have a role in the induction and function of monocyte-derived tolerogenic DC in humans, but these findings do not exclude a role for AIRE in peripheral tolerance mediated by other cell types.     

Renal dendritic cells adopt a pro-inflammatory phenotype in obstructive uropathy to activate T cells but do not directly contribute to fibrosis

Unilateral ureteral obstruction (UUO) is a well-characterized murine model of renal inflammation leading to fibrosis. Renal dendritic cells (DCs) constitute a significant portion of kidney leukocytes and may participate in local inflammation and have critical roles in antigen presentation. The heterogeneity in renal DC populations and surface marker overlap with monocytes/macrophages has made studying renal DCs difficult. These studies used CD11c-promoter driven reporter/depletion mice to study DCs in vivo. Studying early local inflammatory events (day 3 of UUO), in vivo multiphoton imaging of the intact kidney of CD11c reporter mice revealed more dendrite extensions and increased activity of renal DCs in real time. Phenotypic analysis suggested resident DC maturation in obstructed kidneys with increased CD11b and less F4/80 expressed. CD11b(hi) Gr-1(+) inflammatory DCs were also present in obstructed kidneys. T-cell receptor transgenic mice revealed enhanced antigen-presenting capacity of renal DCs after UUO, with increased antigen-specific T-cell proliferation in vivo and ex vivo. However, conditional DC ablation at days 0, 2, or 4 did not attenuate fibrosis or apoptosis 7 days after UUO, and depletion at 7 days did not alter outcomes at day 14. Therefore, after UUO, renal DCs exhibit inflammatory morphological and functional characteristics and are more effective antigen-presenting cells, but they do not directly contribute to tubulointerstitial damage and fibrosis.     

Mutants of bacteriophage λ which do not require the cIII gene for efficient lysogenization

The λ cIII gene is ordinarily required for the high rate, establishment mode of repressor synthesis and efficient lysogenization by phage λ We have isolated phage mutants (called can) which no longer require cIII for efficient lysogenization by selecting turbid plaque-forming pseudorevertants of phages carrying a deletion of cIII. Three different kinds of can mutations have been characterized: can10, which is located in the cro gene; can15, which appears to be identical to cin1 and which is located in the left part of the y region; and can1, which is located in the right part of they region, among the clear cy mutations. Can10 and the previously identified cro^? mutation, cro27, both improve lysogenization frequency in the absence of cIII function, possibly because of overproduction of cII protein. In addition, lysogenization by λcIII⁺ phages carrying these mutations is more efficient than by λ⁺ at low multiplicity of infection. The cro27 mutation also improves lysogenization by cII^? phages, suggesting that Cro may prevent premature synthesis of repressor in the maintenance mode. Can1 is dominant to can⁺ and partially relieves the lysogenization defect of λcIII^? in a cap^?cya^? host. The ability of λcIII^?cI^?can1 to stimulate lysogenization by λcIII^?cI⁺ indicates that can1 does not require an adjacent functional cI gene for its action and that can1 affects the activity of a diffusible product, presumably cII protein. This proposal is supported by a cis-trans test showing that can1 requires an adjacent functional cII gene. Although can1 does not increase the frequency of lysogenization in the absence of cII function, it does increase lysogenization frequency when cII activity is present but limiting. These observations suggest that can1 increases the level or activity of cII protein. Based on the ability of can1 and can10, to bypass the need for cIII, we propose that the role of cIII protein in stimulating repressor synthesis is indirect; it acts by increasing activity of the cII protein.     

Mouse B cells do not proliferate in human interleukin 2

By pre-activation with a monoclonal anti-IgM antibody coupled to Sepharose, either in the absence or presence of low doses of lipopolysaccharide, mouse B cell populations were rendered responsive to recombinant DNA derived human interleukin 2 (IL2). However, if the B cell populations were subjected to separation based on their buoyant density before pre-activation, only low but not high buoyant density cells became responsive to IL2. Both cell populations subscquent to anti-IgM pre-activation were equally responsive to a Sephadex G-100 fraction of supernatants from rat spleen cells stimulated with concanavalin A. Furthermore, the differences in the IL2 titration curves on T and B cell populations indicate that only a subpopulation of cells are responding to IL2 in the B cell populations. In B cell populations that did respond to IL2, a population of Thy-1.2-positive cells appeared. The proportion of IL2-responsive T cells needed to give a significant signal when admixed with nonresponding B cell populations was quantitated to be less than 1 %.     

树突状细胞疫苗在肿瘤免疫治疗中的作用

树突状细胞是机体内专职的抗原提成细胞,能激活初始型T细胞,因此在免疫反应中具有独特的作用.近年来DC在肿瘤的免疫治疗中的作用受到重视,其发展迅速.本文就这方面的研究进行综述,包括DC与肿瘤发生发展的关系、DC在肿瘤治疗中的具体应用方式、DC疫苗的临床应用研究进展,并重点讲述了以DC为中心的基因治疗方面的进展.     

Gammadelta T cells do not require fully functional cytotoxic pathways or the ability to recognize recipient alloantigens to prevent graft rejection.

Gammadelta T cells are a unique and minor T-cell subset that differs from conventional alphabeta T cells by virtue of their tissue localization and antigen processing requirements. We have previously shown that ex vivo-activated gammadelta T cells are able to prevent graft rejection without causing clinically significant graft-versus-host disease (GVHD). In the present study, we examined how gammadelta T cells facilitate alloengraftment and to what extent mechanisms used by conventional alphabeta T cells are also used by gammadelta T cells. We observed that, unlike alphabeta T cells, for which CD8(+) T cells are primarily responsible for facilitating engraftment, purified CD8(+)gammadelta(+) T cells administered at the same fractional dose as for the unseparated activated gammadelta T-cell population were insufficient to prevent graft rejection. Furthermore, the ability to prevent graft rejection was not affected by the absence of fully functional fas ligand or perforin cytotoxic pathways, nor was it contingent on the ability of gammadelta T cells to recognize recipient major histocompatibility process alloantigens. Repetitive infusions of a suboptimal dose of gammadelta T cells however were able to rescue mice from graft rejection, suggesting that the persistence of these cells in vivo was critical in facilitating alloengraftment. These studies demonstrate that gammadelta T cells do not use mechanisms used by conventional nontolerant alphabeta T cells to prevent graft rejection. The ability of these cells to promote engraftment without causing GVHD further distinguishes these cells from alphabeta T cells and may be an attribute that can be exploited in the clinical transplantation setting.     

The use of dendritic cells in cancer immunotherapy

A novel approach to vaccination against cancer is to exploit dendritic cells (DCs) as "nature's adjuvants" and actively immunize cancer patients with a sample of their own DCs primed with tumor antigens. DC vaccination is, however, still at an early stage, slowed in part by the need to carry out research in humans. Nevertheless, valuable proofs of concept have been obtained with respect to the capacity of DCs to expand cancer-directed immune responses. The methods for preparing DCs are being improved continuously, and there are many opportunities to improve efficacy at the level of DC biology. An increased number of Phase I, II and III studies will drive this new area of human research.     

The role of dendritic cells in neuroblastoma: Implications for immunotherapy

Neuroblastoma is a solid tumor, which is originated from some neural tissues. The immune system including the innate and adaptive immune system fights against this tumor. Dendritic cells (DCs) play an important role in this way by recognizing tumor antigens and activating specific types of T cells. These cells are derived from monocytes that are induced by inflammatory factors secreted by different cells in the tumor microenvironment (TME). There are different types of DCs, including monocyte-derived DCs (moDC), plasmacytoid DCs (pDC), conventional DCs type 1 and 2 (cDC1 and cDC2), and Langerhans cells. DCs connect the innate and the adaptive part of the immune system and have an important role in anti-tumor immunity. There are some vaccines that involve specific types of DCs, which can be used to prevent neuroblastoma. Also, we can use the combination of inflammatory factors and DCs as a substitute for chemotherapy.     

Cancer immunotherapy using virally transduced dendritic cells: animal studies and human clinical trials

The immune system uses a process known as 'immunosurveillance' to help prevent the outgrowth of tumors. In cancer immunotherapy, a major goal is for immunity against tumor-associated antigens to be generated or strengthened in patients. To achieve this goal, several approaches have been tested, including the use of highly potent antigen-presenting cells called dendritic cells (DCs), which can activate T cells efficiently. Presentation of peptides derived from tumor antigens on the surface of DCs can stimulate strong antitumor immunity. Using recombinant viral vectors encoding tumor-associated antigens, DCs can be engineered efficiently to express sustained levels of tumor-antigen peptides. This review discusses the effectiveness of virally transduced DCs in treating tumors and generating antigen-specific T-cell responses. It covers mouse and nonhuman primate studies, preclinical in vitro human cell experiments and clinical trials.     

A simple and convenient method for producing anti-activated lymphocyte alloantisera which does not require prior absorption

A BALB/c B cell lymphoma, 2PK-3, was found to be activation lymphocyte alloantigen (Ala-1)-positive by virtue of its ability to absorb out the cytotoxic anti-Ala-1.1-like antibody activity of an antiserum against activated BALB/c (Ala-1.1) lymphocytes. Injection of 2PK-3 cells from the spleens or ascites of lymphomatous BALB/c mice into H-2d compatible DBA/2 mice led to the rapid development of an antiserum with properties identical to anti-Ala-1.1 alloantisera. Thus, it did not significantly kill normal spleen cells from any one of 7 different strains tested, but killed over 85% of Con A- or LPS-stimulated spleen cells of 4 Ala-1.1 positive strains; activated lymphocytes of Ala-1.2 were not affected. Furthermore, these properties were seen with unabsorbed antisera. The results indicate that the Ala-1 phenotype may, in some cases, be retained on neoplastic lymphocytes and that such cells, being rapidly and easily obtained in vivo in large quantities, can serve as a convenient source of immunogen for the development of anti-Ala-1 alloantisera in certain donor-recipient combinations.