(L18) Introduction to the Immune System Flashcards
What are the main elements of the immune system and what do they consist of?
L18 S2
Fixed elements:
- primary lymphoid organs (bone marrow and thymus)
- secondary lymphoid organs (spleen, lymph nodes, mucosal immune tissue)
Mobile elements:
- immune cells (T and B cells)
- Abs
- cytokines
- complement
- APP
What is the innate and adaptive immunity?
What are their components and when are they activated during the course of an infection?
L18 S3
Innate:
- no memory (no TCR/BCR)
- consists of physical barriers, phagocytes, DCs, complement, NK cells
Adaptive:
- has memory (TCR/BCR)
- T cells or B cells
What are the immune cells of lymphoid and myeloid lineage?
L18 S4-5
Myeloid lineage: -granulocytes (G-CSF) —basophil —eosinophil —neutrophil —monocyte -agranulocytes (M-CSF) —monocytes/macrophages —dendritic cells
Lymphoid lineage: -B-cell precursor —B lymphocytes -T-cell precursor —T lymphocytes —NK cell
What are the main WBC types identified in a CBC and what is the prevalence of each?
L18 S11
Neutrophils: 40-70% Eosinophils: 1-4% Basophils: 0.5-1% Monocytes: 2-8 Lymphocytes: 20-40%
What clusters of differentiation (CD) are indicative of T cells, B cells, NK cells, and macrophages/monocytes?
L18 S13
T cell:
- CD3/CD4 (T helper)
- CD3/CD8 (cytotoxic T cell)
B cell:
-CD19/CD20
NK cell:
-CD56
Macrophage/monocyte:
-CD14
What is the function of a phagocyte and what are the main types of phagocytes?
L18 S17
Function:
- recruitment of cells to site of infection (chemokines)
- recognition of microbes
- ingestion of microbe (phagocytosis)
- destruction of ingested microbes
Types:
- neutrophil
- monocyte
- macrophage
What are the main functional and histologic features of neutrophils?
L18 S18
Function:
- mediate earliest response to inflammatory reactions
- phagocytic
- produce cytokines
Histologic characteristics:
- most abundant WBC
- cytoplasmic granules cotaining peroxidase, lysozyme, degradative enzymes, defensins
- polymorphonuclear (PMN); 3-5 lobed nucleus
- significant amount stored in the bone marrow
What are the effector killing mechanisms of neutrophils?
L18 S25
Phagocytosis: ingestion of pathogen and exposure to ROS (intracellular)
Degranulation: release of granule contents that kill pathogen (extracellular)
Neurophil extracellular traps (NETs): DNA element with associated proteins that snares and immobilized pathogen facilitating phagocytosis (extracellular)
What is the most efficient antigen presenting cell (APC)?
L18 S27
Dendritic cells (DCs)
What are resident Mφ?
L18 S29
Long-lived macrophages that are developed in the fetal hematopoietic sites.
Migrate to different locations and take up specialized roles in that tissue
What are tissue Mφ?
L18 S30
Derived from circulating monocytes and differentiate into Mφ.
Involved in:
- inflammatory reactions
- tissue remodeling
Differentiate between mDCs and pDCs.
L18 S31
Myeloid DCs:
- derived from monocytes
- capture, process, and present Ags in tissue to T cells
Plamacytoid DCs:
- IFN-producing DCs
- circulate in blood
What are mast cells and basophils?
What are their functions and histologic features?
L18 S34
Basophil is circulating, mast cell is in tissue
Function:
- defense agains parasites
- allergic/anaphylactic reactions
Histology:
- polymorphonuclear
- basophilic, granules containing histamine, serotonin, heparin, and cytokines/chemokines
What are eosinophils?
What are their functions and histologic features?
L18 S36
Function:
- defense agains parasites
- allergic reactions (tissue damage as well)
Histology:
- polymorphonuclear
- large granules containing basic proteins
- small granules containing histamine, peroxidase, lipase, and major basic protein
What is the function of NK cells?
L18 S42
Respond to signals (typically the lack of a healthy cell membrane component) indicating infected cells and precancerous cells
Kills cells expressing these signals
