Alum has been the most widely used adjuvant for over 80 years. Although there have been searches for alternative adjuvants, aluminium-containing adjuvants will continue to be used for many years due to their good track record of safety, low cost and adjuvanticity with a variety of antigens. For infections that can be prevented by induction of serum antibodies, aluminium-containing adjuvants formulated under optimal conditions are the adjuvants of choice. There are also some limitations of aluminium-containing adjuvants, which include local reactions, augmentation of IgE antibody responses, ineffectiveness for some antigens and inability to augment cell-mediated immune responses, especially cytotoxic T-cell responses. In this review, we describe the current knowledge regarding the mechanisms (both cellular and molecular) by which alum employs its adjuvant effect, although the final mechanism is not yet well-defined. Furthermore, we discuss how alum’s adjuvanticity could be improved.

Immune cell activation is a stringently regulated process, as exaggerated innate and adaptive immune responses can lead to autoinflammatory and autoimmune diseases. Autoinflammation and autoimmunity are mediated by aberrantly activated immune cells, either innate or adaptive immune cells. Perhaps the best-characterized molecular pathway in immune cell activation is the nuclear factor-κB (NF-κB) signalling pathway leading to transcription of numerous pro-inflammatory and cell-survival genes. NF-κB activation is tightly controlled by several mechanisms, including the key regulatory zinc-finger (de)ubiquitinating enzyme A20/TNFAIP3. Single nucleotide polymorphisms (SNPs) in the vicinity of the TNFAIP3 gene are associated with a spectrum of chronic systemic inflammatory diseases, indicating its clinical relevance. Mice harboring targeted cell-specific deletions of the Tnfaip3 gene in innate immune cells like macrophages spontaneously develop autoinflammatory disease. In contrast, when immune cells involved in the adaptive immune response, like dendritic cells or B-cells are targeted for A20/TNFAIP3 deletion, mice develop spontaneous inflammation that resemble human autoimmune disease. Therefore, more knowledge on A20/TNFAIP3 function in innate and adaptive immune cells is beneficial in our understanding of autoinflammation and autoimmunity. Using the above mentioned mouse models, novel A20/TNFAIP3 functions have recently been described such as control of necroptosis and inflammasome activity. In this review, we discuss the function of the A20/TNFAIP3 enzyme, and its critical role in various innate and adaptive immune cells. Lastly, we discuss the latest findings on A20/TNFAIP3 SNPs in human autoinflammatory and autoimmune diseases and address that genotyping of TNFAIP3 SNPs may guide treatment decisions.

Sarcoidosis is a granulomatous disorder of unknown cause, affecting multiple organs, but mainly the lungs. The exact order of immunological events remains obscure. Reviewing current literature, combined with careful clinical observations, we propose a model for granuloma formation in pulmonary sarcoidosis. A tight collaboration between macrophages, dendritic cells and lymphocyte subsets, initiates the first steps towards granuloma formation, orchestrated by cytokines and chemokines. In a substantial part of pulmonary sarcoidosis patients, granuloma formation becomes an on-going process, leading to debilitating disease and sometimes death. The immunological response, determining granuloma sustainment is not well understood. An impaired immunosuppressive function of regulatory T cells has been suggested to contribute to the exaggerated response. Interestingly, therapeutical agents commonly used in sarcoidosis, such as glucocorticosteroids and anti-TNF agents, interfere with granuloma integrity and restore the immune homeostasis in autoimmune disorders. Increasing insight into their mechanisms of action may contribute to the search for new therapeutical targets in pulmonary sarcoidosis.

The lung-draining mediastinal lymph nodes (MLNs) are currently widely used to diagnose sarcoidosis. We previously reported that T-helper (Th) 17.1 cells are responsible for the exaggerated interferon-γ production in sarcoidosis lungs. In this study, we aimed to investigate 1) whether Th17.1 cells are also increased in the MLNs of sarcoidosis patients and 2) whether frequencies of the Th17.1 cells at diagnosis may correlate with disease progression.MLN cells from treatment-naive pulmonary sarcoidosis patients (n=17) and healthy controls (n=22) and peripheral blood mononuclear cells (n=34) and bronchoalveolar lavage fluid (BALF) (n=36) from sarcoidosis patients were examined for CD4⁺T-cell subset proportions using flow cytometry.Higher proportions of Th17.1 cells were detected in sarcoidosis MLNs than in control MLNs. Higher Th17.1 cell proportions were found in sarcoidosis BALF compared with MLNs and peripheral blood. Furthermore, BALF Th17.1 cell proportions were significantly higher in patients developing chronic disease than in patients undergoing resolution within 2 years of clinical follow-up.These data suggest that Th17.1 cell proportions in pulmonary sarcoidosis can be evaluated as a diagnostic and/or prognostic marker in clinical practice and could serve as a new therapeutic target.

Asthma is a heterogeneous chronic inflammatory disease of the airways, with reversible airflow limitations and airway remodeling. The classification of asthma phenotypes was initially based on different combinations of clinical symptoms, but they are now unfolding to link biology to phenotype. As such, patients can suffer from a predominant eosinophilic, neutrophilic or even mixed eosinophilic/neutrophilic inflammatory response. In adult asthma patients, eosinophilic inflammation is usually seen in mild-to-moderate disease and neutrophilic inflammation in more severe disease. The underlying T cell response is predominated by T helper (Th) 2, Th17, or a mixed Th2/Th17 cell immune response. Dendritic cells (DCs) are "professional" antigen presenting cells (APCs), since their principal function is to present antigens and induce a primary immune response in resting naive T cells. DCs also drive the differentiation into distinctive Th subsets. The expression of co-stimulatory molecules and cytokines by DCs and surrounding cells determines the outcome of Th cell differentiation. The nature of DC activation will determine the expression of specific co-stimulatory molecules and cytokines, specifically needed for induction of the different Th cell programs. Thus DC activation is crucial for the subsequent effector Th immune responses. In this review, we will discuss underlying mechanisms that initiate DC activation in favor of Th2 differentiation versus Th1/Th17 and Th17 differentiation in the development of mild versus moderate to severe asthma.