Biology » The Immune System » Adaptive Immune Response

Summarizing Adaptive Immune Response


The adaptive immune response is a slower-acting, longer-lasting, and more specific response than the innate response. However, the adaptive response requires information from the innate immune system to function. APCs display antigens via MHC molecules to complementary naïve T cells. In response, the T cells differentiate and proliferate, becoming TH cells or CTLs. TH cells stimulate B cells that have engulfed and presented pathogen-derived antigens. B cells differentiate into plasma cells that secrete antibodies, whereas CTLs induce apoptosis in intracellularly infected or cancerous cells. Memory cells persist after a primary exposure to a pathogen. If re-exposure occurs, memory cells differentiate into effector cells without input from the innate immune system. The mucosal immune system is largely independent from the systemic immune system but functions in a parallel fashion to protect the extensive mucosal surfaces of the body.


adaptive immunity

immunity that has memory and occurs after exposure to an antigen either from a pathogen or a vaccination


foreign or “non-self” protein that triggers the immune response

antigen-presenting cell (APC)

immune cell that detects, engulfs, and informs the adaptive immune response about an infection by presenting the processed antigen on the cell surface

autoimmune response

inappropriate immune response to host cells or self-antigens

cell-mediated immune response

adaptive immune response that is carried out by T cells

clonal selection

activation of B cells corresponding to one specific BCR variant and the dramatic proliferation of that variant

cytotoxic T lymphocyte (CTL)

adaptive immune cell that directly kills infected cells via perforin and granzymes, and releases cytokines to enhance the immune response

dendritic cell

immune cell that processes antigen material and presents it on the surface of other cells to induce an immune response

effector cell

lymphocyte that has differentiated, such as a B cell, plasma cell, or cytotoxic T lymphocyte


small component of an antigen that is specifically recognized by antibodies, B cells, and T cells; the antigenic determinant

helper T lymphocyte (TH)

cell of the adaptive immune system that binds APCs via MHC II molecules and stimulates B cells or secretes cytokines to initiate the immune response

humoral immune response

adaptive immune response that is controlled by activated B cells and antibodies

immune tolerance

acquired ability to prevent an unnecessary or harmful immune response to a detected foreign body known not to cause disease or to self-antigens


watery fluid that bathes tissues and organs with protective white blood cells and does not contain erythrocytes

mucosa-associated lymphoid tissue (MALT)

collection of lymphatic tissue that combines with epithelial tissue lining the mucosa throughout the body

memory cell

antigen-specific B or T lymphocyte that does not differentiate into effector cells during the primary immune response but that can immediately become an effector cell upon re-exposure to the same pathogen

plasma cell

immune cell that secrets antibodies; these cells arise from B cells that were stimulated by antigens

regulatory T (Treg) cell

specialized lymphocyte that suppresses local inflammation and inhibits the secretion of cytokines, antibodies, and other stimulatory immune factors; involved in immune tolerance

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