Overview of Adaptive Immune System

Flashcards summarizing key concepts related to the adaptive immune system, lymphocyte development, and immune responses.

Thymocytes

Pre-T-lymphocytes that develop in the thymus after migrating from the red bone marrow.

Positive selection

The process where double-positive thymocytes are tested for their ability to bind to MHC class I or II proteins, allowing survival.

Negative selection

The process where thymocytes that bind strongly to self-antigens undergo apoptosis to prevent autoimmune diseases.

B-lymphocytes

Lymphocytes that originate and complete their development in the red bone marrow, expressing unique B-cell receptors.

Somatic recombination

A gene-shuffling process that leads to the diversification of B-cell receptors (BCRs) and T-cell receptors (TCRs).

B-cell receptor (BCR)

A Y-shaped immunoglobulin molecule on B-lymphocytes capable of binding to specific antigens.

CD4+ T-cells

Naive helper T-lymphocytes that help activate other immune cells.

CD8+ T-cells

Naive cytotoxic T-lymphocytes that kill infected or unhealthy cells.

MHC class I

Major histocompatibility complex molecules that present endogenous antigens to CD8+ T-lymphocytes.

MHC class II

Major histocompatibility complex molecules that present exogenous antigens to CD4+ T-lymphocytes.

Agglutination

An antibody function where foreign cells are clumped together by cross-linking.

Opsonization

A process where antibodies mark antigens for phagocytosis by binding to their Fc regions.

Interleukin-2 (IL-2)

A cytokine released by activated T-lymphocytes that stimulates their own proliferation and differentiation.

Cytotoxic T-lymphocyte

A T-cell type that directly kills virus-infected cells and recognizes antigens presented by MHC class I.

Helper T-lymphocyte activation

Activation that occurs when the TCR binds to exogenous antigens presented with MHC class II.

Plasma cells

Differentiated B-lymphocytes that secrete specific antibodies after activation.

Memory cells

Long-lived B or T cells that respond more rapidly upon re-exposure to the same antigen.

Perforin

A protein secreted by cytotoxic T-lymphocytes that creates pores in target cell membranes.

Granzymes

Proteolytic enzymes secreted by cytotoxic T-lymphocytes to induce apoptosis in infected cells.

Antigen-binding site

The specific region of an antibody that binds to an antigen.

Complement activation

A process triggered by antibodies that enhances immune response and promotes pathogen lysis.

Naive B-lymphocyte

A B-cell that has not yet encountered its specific antigen.

Thymic dendritic cells

Cells in the thymus that present self-antigens for negative selection of thymocytes.

Endogenous antigens

Antigens that originate from within the cell, typically from viral infections.

Exogenous antigens

Antigens that originate from outside the cell, such as those from bacteria.

Thymosin

A hormone produced in the thymus that stimulates thymocyte development.

Effector T-lymphocytes

Activated T-cells that perform functions such as killing infected cells or helping B-cells.

Antibody monomer

A single unit of antibody, comprising a Y-shaped structure with distinct regions.

Fc region

The stem of an antibody that determines its class and mediates interaction with other immune components.

Neutralization

An antibody function where it binds to biologically active antigens, rendering them harmless.

Cytokines

Signaling molecules released by immune cells to mediate and regulate immune responses.

Double-positive thymocytes

Thymocytes expressing both CD4 and CD8 co-receptors before undergoing selection processes.

Thymic selection processes

The critical screening steps that thymocytes undergo, including positive and negative selection.

Adaptive immunity

The specific immune response that develops following exposure to antigens, involving B and T lymphocytes.