Immunoproteins

Immunoproteins are a broad group of proteins that participate in the immune response. They include antibodies (immunoglobulins), components of the complement system, cytokines and chemokines, and several acute-phase and other regulatory proteins. Immunoproteins can be produced by immune cells such as B and T lymphocytes and macrophages, and by the liver and other tissues in response to inflammatory signals. They function together to recognize, attack, and regulate pathogens and damaged cells.

Antibodies are Y-shaped immunoglobulins produced by B cells. They bind specifically to antigens via the antigen-binding fragments (Fab) and recruit effector mechanisms through the constant region (Fc). Antibodies exist in several classes (IgG, IgA, IgM, IgD, IgE) with distinct roles in extracellular defense, mucosal immunity, and allergic responses.

The complement system comprises a set of plasma proteins that become activated in cascades. Activation leads to opsonization of pathogens, recruitment of inflammatory cells, and, in some cases, direct lysis of foreign cells via the membrane attack complex.

Cytokines and chemokines are small secreted proteins that coordinate immune cell communication and movement. Examples include interleukins, interferons, tumor necrosis factor, and chemokines; they regulate cell activation, differentiation, and trafficking during infection and inflammation.

Acute-phase proteins, such as C-reactive protein (CRP) and serum amyloid A, are produced by the liver in response to inflammatory signals and modulate the immune response. They serve as biomarkers of inflammation and can influence complement activation and phagocytosis.

Clinical relevance: Abnormal levels or function of immunoproteins can indicate immunodeficiency, autoimmunity, infection, or inflammatory disease. Measurement of immunoglobulin levels, complement components, CRP, and cytokines can aid diagnosis and monitoring.