EPIC platform provides a way to analyze B cell activation and find treatments for autoimmune disease

The human immune system, comprised of the innate immune response and the adaptive immune response, is crucial to the maintenance of homeostasis. Innate immunity involves the initial combative actions by macrophages and neutrophils towards a foreign antigen soon after it has entered the body. Innate immunity fights pathogens in the same way each time, regardless of the specificity of the pathogen. Adaptive immunity is the body’s more specified and targeted response to an antigen based on what the antigen is and whether it has been encountered before. The adaptive immune response can take several days to become fully activated. B cells, also known as B lymphocytes, are involved in immunological memory and are part of the adaptive immune response (C.A. Janeway et al., 2012).

B cells are a form of immune cells, which regulate antibody secretion. They are produced in the bone marrow and are responsible for generating antibodies, which bind onto pathogens in order to tag them for destruction. B cells are activated by two separate signals, the first of which involves an antigen binding to the B cell receptor (BCR). The B cell, which is an antigen-presenting cell, will then present the bound antigen on its surface. The second signal occurs when a CD40 ligand, exhibited on the surface of a T cell, binds to the B cell’s CD40 receptor. B cells can then undergo proliferation, differentiation, and subsequent antibody secretion (E.B. Rex et al., 2015). B cell activation initiates a signaling cascade within the cell, which will eventually allow the B cell to express a version of lymphocyte function-associated antigen 1 (known as LFA-1) that can bind to target cells expressing intercellular adhesion molecule 1 (ICAM-1). These target cells can be leukocytes, dendritic cells or follicular dendritic cells. This LFA-1/ICAM-1 interaction helps the B cells to recognize their target.

Dr. Rex and colleagues from Janssen Research and Development (La Jolla, USA) used both Ramos and RL B cells in a label-free EPIC platform, which relies on ICAM-1-coated plates to mimic target cells and allow B cells to adhere. An optical biosensor then measures changes in refraction caused by mass redistribution within the cell. The principal objective of this EPIC platform is the evaluation of B cell activation and the identification of modulators of BCR and CD40R-based B cell activation. This phenotypic screening platform was evaluated through comparison to the FLIPR platform (J. Douhan et al., 2007). The difference between these two platforms is the point in the B cell activation pathway during which they recognize inhibition. The FLIPR platform uses a fluorescent, calcium-sensitive dye to detect intracellular calcium release. This calcium release is an intermediate step in the B cell activation pathway. The complementary EPIC platform detects the binding of LFA-1 (located on the B cell’s surface) to ICAM-1 (normally located on the target cell), which is downstream of the FLIPR detection point. Enzo’s human recombinant MEGACD40L® is a high-activity, high-purity CD40L construct for co-stimulatory activation of an immune response. It mimics in vivo membrane-assisted CD40L aggregation and stimulation without the need for enhancers and has lower endotoxin levels than comparable products. Using Enzo’s MEGACD40L®, the authors of this study were able to observe the direct interaction between LFA-1 and ICAM-1.

Unnecessary activation of B cells is an implication in many human diseases, especially autoimmune diseases including lupus and rheumatoid arthritis. Studying B cell activation has recently led to the development and identification of small molecules which impede B cell activation. These molecules can likely be used to treat autoimmune diseases. However, their current use in clinical trials focuses on other diseases such as cancer. For example, the AVL-292 class of inhibitors is currently in use in clinical trials for B cell non-Hodgkin’s lymphoma. These molecules have shown promise in a model of rheumatoid arthritis by inhibiting B cell signaling via an intracellular kinase (Bruton’s tyrosine kinase - BTK) involved in the B cell activation pathway. Thus far, these small-molecule BTK inhibitors have not been used in published clinical trials for autoimmune or inflammatory diseases. Because B cell activation has well defined signaling pathways and a large impact on human health, it is an important area of research with pharmacologically relevant applications and using the EPIC platform could go a long way in helping with the discovery of new modulators of these pathways.

Enzo Life Sciences offers a comprehensive product portfolio for advancing your discoveries in immunology research with a whole portfolio of research reagents and kits, including our MEGACD40L® (soluble) (human), (recombinant). In addition, Enzo offers immunology-related antibodies, immunoassays, live cell analysis kits, and proteins, some of which are listed below.

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