Immune responses

Immune responses refer collectively to the processes by which an organism detects and eliminates foreign substances such as pathogens (bacteria, viruses), abnormal cells (such as cancer), and other threats. The term encompasses both innate immunity—the immediate but non-specific defense mechanisms including physical barriers and phagocytic cells—and adaptive immunity—which involves highly specialized lymphocytes (T cells and B cells) that provide targeted attack against invaders along with long-term memory for faster future protection[2][4][5]. Key features include: - Recognition of antigens via pattern recognition receptors or antigen-specific receptors. - Activation cascades involving cytokine release and recruitment/differentiation of various leukocyte populations. - Effector functions such as antibody production by B cells or cytotoxic activity by T lymphocytes. - Resolution phases leading either to tissue healing/scarring or chronic inflammation if dysregulated. The concept also includes pathological variants where these processes become misdirected—as in autoimmune diseases—or insufficient—as in immunodeficiency states. While drugs can enhance or suppress elements within these pathways for therapeutic benefit, there is no single molecular entity called "immune response"[2][8]. > The immune system consists of cellular components and molecular components that work together to destroy antigens... A critical first step in an effective immune response is activation... Upon activation T & B cells differentiate & acquire effector functions including production of cytotoxic anti-pathogen molecules & antibodies.[4][5]

Other names

Immune reactionImmunological responseHost defense response