The immune system uses secreted molecules that regulate immune responses or allow immune cell communication to combat infections, and which play key roles in coordinating both the innate and adaptive immune responses. Cytokines are secreted by immune cells and modulate various immune responses. They act as signalling molecules with interleukins (IL), interferons (IFN), tumour necrosis factors (TNF), and transforming growth factor-beta (TGF-β) examples of key cytokines. Cytokines and cytokine signalling can have diverse effects, including promoting inflammation, activating immune cells, regulating immune cell growth, and influencing immune cell differentiation and maturation. Chemokines consist of a subgroup of cytokines that function specifically in cell migration. Their function is to attract immune cells towards specific locations in response to infection, injury, or inflammation in particular regions of the body. Chemokines thereby help guide immune cells to sites of infection, ensuring spatially appropriate immune responses. Examples include CXCL8 (IL-8) involved in neutrophil recruitment and CCL21 involved in the process of T cell homing to high endothelial venules (HEVs), specialized blood vessels found in secondary lymphoid organs. Interferons (such as IFN-α and IFN-β) are specialized types of cytokines produced in response to viral infections. Interferons have antiviral properties and help limit viral spread. They also enhance the expression of MHC class I molecules, thereby promoting the presentation of viral antigens to T cells. The complement system consists of a group of secreted proteins and proteolytic cleavage reactions that contribute to innate immunity by opsonizing pathogens, promoting inflammation, and by directly lysing target cells through the formation of membrane attack complexes (MACs) which create pores in the target cell's membrane. Complement activation occurs through either the classical (antibody-dependent), lectin (mannose-binding lectin (MBL) and MBL-associated serine proteases (MASPs)), and alternative (spontaneously C3 hydrolysis) pathways. Antibodies are the Y-shaped proteins secreted by plasma (B cells) in response to foreign antigens. Antibodies play a central role in the processes of adaptive immunity by recognizing and neutralizing foreign pathogens. Antibodies can opsonize pathogens for phagocytosis, activate the complement system, and facilitate the process of antibody-dependent cell-mediated cytotoxicity (ADCC), in which specific cells of the immune system, primarily natural killer (NK) cells and macrophages, are activated to recognize and kill target cells that are coated with antibodies. Autoimmune diseases arise when the immune system cannot distinguish between self and non-self-antigens, leading to the production of autoantibodies. Autoantibodies can also activate the complement system or recruite other immune cells through Fc receptors leading to inflammation, tissue destruction, and organ dysfunction. Growth factors are secreted proteins that stimulate cell growth, proliferation, and differentiation of many cell types. In the immune system they are important for immune cell development and maintenance. For example, Granulocyte colony-stimulating factor (G-CSF) and macrophage colony-stimulating factor (M-CSF) regulate the growth and differentiation of granulocytes and macrophages, respectively. Finally, the CCN family of secreted proteins, CCN1 (Cyr61), CCN2 (CTGF), and CCN3 (NOV) mediate interactions and play roles in recruitment of immune cells to sites of inflammation or injury, contributing to the immune cell composition in tissues. We offer a wide product catalogue of research tools for investigating secreted molecules, including Lck antibodies, LAMP2 antibodies, CTGF antibodies, CTGF ELISA Kits, and Granulin ELISA Kits. Explore our full secreted molecules product range below and discover more, for less. Alternatively, you can explore our Other Secreted Molecules and CCN Family product ranges.