Immunology Fundamentals - Vocabulary Flashcards

41 vocabulary flashcards summarizing the key terms and definitions from the immunology study guide.

What is Immunity?

The body’s ability to resist or eliminate potentially harmful foreign materials or abnormal cells.

What is Innate Immunity?

Immediate, non-specific defense mechanisms such as physical barriers, phagocytes, and inflammation.

What is Adaptive (Acquired) Immunity?

Specific immune responses that develop after exposure and provide long-lasting memory.

What is Self-Tolerance?

The immune system’s capacity to avoid attacking the body’s own cells and tissues.

What happens to T and B cells that react to self-antigens?

Usually eliminated during development

Which cells are involved in Lymphoid Lineage?

B cells, T cells, and NK cells.

Where do the lymphoid lineage cells come from?

Arise from lymphoid stem cells and they form the basis of adaptive immunity and immune surveillance.

What are Myeloid Lineage cells?

Blood cell lines that produce neutrophils, monocytes, eosinophils, basophils, macrophages, and dendritic cells.

What are the myeloid lineage cells involved in?

Innate immunity. Included are phagocytes and granulocytes.

Which are the primary organs that develop and mature lymphoids?

Bone marrow and thymus

Where are B cells developed and matured?

Bone marrow

What is the role of the Thymus gland?

Primary organ responsible for T-cell development and maturation.

What does it mean that the T cells develop?

They learn how to distinguish self from non-self

What happens to the thymus during adolescence?

Shrinks and the body relies on already developed T cells and memory cells.

What are phagocytic cells?

Neutrophils, macrophages, dendritic cells

What do Neutrophils, macrophages, dendritic (phagocytic cells) do?

They ingest and digest pathogens and are part of the innate immunity.

What are Neutrophils?

First-responder phagocytes that ingest pathogens and stain with both acidic and basic dyes.

What are Monocytes?

Circulating precursors that differentiate into macrophages within tissues.

Macrophages

Large phagocytes derived from monocytes; engulf pathogens and present antigens.

What are APCs (Antigen presenting Cells)?

Dendritic cells, macrophages, and B cells

What do APCs do?

Capture, process and present antigens to T cells using MHC II.

Which cell is best at presenting antigens to naive T cells?

Dendritic cells

What are Dendritic Cells?

The most efficient antigen-presenting cells (APCs) that initiate T-cells

What is the main role of dendritic cells?

Bridge innate and adaptive immunity through antigen presentation

What do dendritic cells do?

They detect pathogens early and alert the adaptive system by activating T cells

What are Phagocytic Cells?

Cells (neutrophils, macrophages, dendritic cells) that engulf and digest pathogens.

What are Antigen-Presenting Cells (APCs)?

Cells (dendritic cells, macrophages, B cells) that display processed antigens on MHC II to T cells.

What are Cytotoxic T Cells (CD8⁺)?

T cells that destroy virus-infected or tumor cells

How do Cytotoxic T Cells (CD8⁺) work?

They kill cells by releasing enzymes that trigger apoptosis

What do Helper T Cells (CD4⁺) do?

T cells that coordinate immune responses by activating B cells, cytotoxic T cells, and macrophages through cytokines.

What are B Cells?

They are Lymphocytes that produce antibodies and can present antigens via MHC II.

What happens when B cells are activated?

They differentiate into plasma cells to secrete antibodies.

What are Plasma Cells?

Antibody-secreting effector cells derived from activated B cells.

What do plasma cells do?

They secrete large amounts of antibodies tailored to the pathogen

What are Natural Killer (NK) Cells?

Innate lymphocytes that destroy infected or cancerous cells without requiring MHC I recognition.

What is unique about NK cells?

They don’t need MHC I

Why are NK cells essential?

Because they can detect abnormal cells that evade normal detection

What happens to cancer cells that lack MHC I?

NK cells target and destroy them. Losing MHC I is a common escape mechanism of tumors.

What are Antibodies (Immunoglobulins)?

Proteins that bind antigens to neutralize pathogens or flag them for destruction by immune cells.

What is Class Switching?

Process by which activated B cells change antibody isotypes allowing the antibodies to perform different roles. (e.g., IgM to IgG, IgA, IgE).

What is Antibody-Dependent Cellular Cytotoxicity (ADCC)?

Killing of antibody-coated target cells by NK cells or other effector cells.

What’s the relationship between antibodies and killer cells?

Antibodies bind to the infected cells flagging it and attract the killer cells to destroy them.

Which immune cells are activated by antibodies during allergic reactions?

Mast cells

What are Mast Cells?

Granulocytes activated by IgE during allergic reactions, releasing histamine.

What is Major Histocompatibility Complex I (MHC I)?

Molecule on all nucleated cells that presents intracellular antigens to CD8⁺ T cells.

What are the roles Major Histocompatibility Complex I (MHC I)?

Display viral or tumor antigens to the immune system.

What is Major Histocompatibility Complex II (MHC II)?

Molecule on APCs that presents extracellular antigens to CD4⁺ helper T cells.

What is the role of Major Histocompatibility Complex II (MHC II)?

Shows antigen from bacteria or external pathogens to activate helper T cells

Where is MHC I expressed?

On all nucleated cells, showing their internal health status to CD8+ T cells

What molecule is found on helper T cells, but not Cytotoxic T cells?

CD4

What role does CD4 have in the immune system?

It’s a surface protein on helper T cells that stabilizes interaction with MHC II. Enduring tight interaction between T cell and APC during activation.

What is the role of CD8 in the immune system?

It’s a surface protein on cytotoxic T cells that stabilizes interaction with MHC I, allowing the cytotoxic cell to recognize and kill the infected cell in front of it.

What do red blood cells lack?

A nucleus and immune related surface proteins

What molecules will not appear on the surface of red blood cells?

MHC I, MHC II, CD4, CD8, TCR

What is Chemotaxis?

Movement of immune cells toward chemical signals (like cytokines) at infection sites.

What causes Clonal Expansion of lymphocytes?

Antigens binding yo their receptors

What happens when a receptor matches an antigen on the lymphocyte cells?

The cells rapidly multiply

Which process leads to immune memory?

Clonal expansion of B & T cells

What is the extravasation phase?

Process by which leukocytes (inflammatory/immune cells) exit blood vessels to reach inflamed tissues.

What is the Complement System?

Plasma protein cascade that enhances pathogen elimination via lysis and opsonization.

which compliment pathway is antibody independent?

Alternative pathway

What system do antibodies activate to help destroy pathogens?

Complement system

how does the compliment system enhance killing of pathogens?

By punching holes or promoting phagocytosis

What is Anaphylaxis?

Severe, systemic allergic reaction causing widespread histamine release and potential shock.

What is Systemic Lupus Erythematosus (SLE)?

Autoimmune disease characterized by antibodies attacking their own tissue.

What is Multiple Sclerosis?

Autoimmune disease that attacks the central nervous system myelin, impairing nerve conduction.

What organ filters blood, removes old red blood cells and is a reservoir for immune cells?

Spleen

What are Toll-Like Receptors (TLRs)?

Innate immune receptors that recognize pathogen patterns and trigger an inflammatory response.

What is the role of Human Leukocyte Antigen (HLA)?

They are responsible for presenting antigens to T cells and defining self tissue.

What are Hematopoietic Stem Cells in immunology?

Bone marrow precursors (found there) that generate all blood cells, including immune lineages.

what are the lineage immune cells created by the bone marrow stem cells?

Myeloid and lymphoid lineages

What is the role of Chemotactic Cytokines (Chemokines)?

Signaling proteins that guide immune cell movement toward sites of infection.

What are Self-Antigens?

Molecules that naturally present in the body that should not trigger an immune response.

How does the innate system respond to a second exposure?

Same response and intensity as the first time. Unlike adaptive immunity.