General Microbiology: Introduction to the Immune System

Flashcards covering key vocabulary terms related to the immune system, including innate and adaptive immunity, immune cells, and immune responses.

Immunity

The state or quality of being resistant to a particular infectious disease or pathogen.

Innate Immunity

Non-specific defense against any pathogen; relies on pattern recognition; born with it.

Adaptive Immunity

Defends against specific pathogens; detection of antigens & production of antibodies; develops throughout life.

Phagocytes

Immune cells including macrophages, neutrophils, eosinophils, and dendritic cells, which engulf and destroy pathogens.

Antigen

Molecule that binds directly to an antibody or indirectly to a T cell receptor (TCR) when bound to a specific type of major histocompatibility (MHC) molecule.

Antibody

Also called an immunoglobulin; a glycoprotein molecule, produced and secreted by B cells; bind to and neutralize antigens, activate the complement system, and promote the phagocytosis and destruction of pathogens.

Active Immunity

Form of adaptive immunity induced by exposure to a foreign antigen (either environmentally or via vaccination), which triggers activation of lymphocytes.

Passive Immunity

Form of adaptive immunity in which antibodies or lymphocytes produced by an immune individual are transferred to a different individual.

Primary Immune Response

Response of the adaptive immune system to the first exposure to an antigen.

Secondary Immune Response

Response of the adaptive immune system to second or subsequent exposures to an antigen (mediated by “memory” cells).

Cell-Mediated Immune Response

Adaptive immune response, triggered by intracellular and phagocytosed antigens, controlled by TC cells and TH cells.

Humoral Immune Response

Adaptive immune response, triggered by extracellular antigens, controlled by activated B cells and their antibodies.

Leukocytes

White Blood Cells found in the blood.

Neutrophils

White blood cells recruited to inflammatory sites & capable of phagocytosis.

Lymphocytes

White blood cells including B cells, T cells, & NK cells

Monocytes

White blood cells that are precursors of tissue macrophages & have different forms in different tissues.

Eosinophils

White blood cells involved in late-phase reactions of immediate hypersensitivity and in defense against helminths.

Basophils

White blood cells structurally & functionally similar to mast cells, but circulate in blood; involved in immediate hypersensitivity (allergic) reactions.

Dendritic cells

Tissue phagocyte that travels to the lymph nodes to function as an antigen-presenting cell (APC) to T cells.

Plasma cells

Terminally-differentiated B cells that secrete antibodies/immunoglobulins.

Mast cells

Similar to basophils, but reside in tissues near blood vessels (not in blood plasma) & function as the primary effector cells of immediate hypersensitivity (allergic) reactions.

Natural killer (NK) cells

Type of lymphocyte that functions in the innate immune response to kill microbe-infected cells and activate phagocytes.