Immunogènes

Immunogènes (immunogens) are substances capable of provoking an adaptive immune response in a host. They are recognized by the immune system and can induce antibody production, T cell activation, and immunological memory. Immunogènes include whole pathogens, their components, and synthetic or natural molecules.

Determinants of immunogenicity include size, complexity, foreignness, stability, and the context of exposure. Adjuvants, used in vaccines, enhance responses by stimulating innate immunity. Some molecules, called haptens, are too small to be immunogenic alone and require a carrier protein.

An immunogen is a substance that elicits an immune response; an antigen is any molecule recognized by immune receptors. All immunogens are antigens, but not all antigens are immunogenic by themselves. Epitopes are the specific parts recognized by antibodies or T cell receptors.

Immunogens can be proteins, polysaccharides, lipids, or nucleic acids. They may invoke humoral (antibody) or cell-mediated immunity. T-dependent antigens require helper T cells, while T-independent ones can stimulate B cells directly. Vaccines often use immunogenic components, sometimes conjugated to carriers to improve responses.

Immunogenicity is assessed by antibody titers, T cell assays, and functional tests such as neutralization. Understanding immunogènes informs vaccinology, allergy, transplantation, and immunotherapy.