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Immunology > Definitions > Flashcards

Flashcards in Definitions Deck (47):
1

HUMORAL IMMUNE SYSTEM

Component of the immune system that resides in the serum (not the difference between serum and plasma)
aka antibodies.

2

CELL MEDIATED IMMUNE SYSTEM

White blood cells (until mid session exam, consider ALL blood cells in this category)

3

INNATE IMMUNITY
(NON-SPECIFIC)

Immune system you're born with. First line of defence, general protection. Neutrophils, NK cells etc.
Both humoral and cell mediated immune systems have an innate and an adaptive component.

4

ADAPTIVE IMMUNITY
(SPECIFIC)

Response to a specific pathogen. Improves with repeat encounters with the same pathogen.
Memory component. B and T lymphocytes etc.
Both humoral and cell mediated immune systems have an innate and an adaptive component.

5

LYSOZYMES

An enzyme which targets peptidoglycan in gram positive cell wall.

6

CYTOKINES

Soluble proteins or peptides which are like mobile phones for immune cells. If a cell needs to communicate with another cell it will release a particular type of cytokine. Only cells with the receptor for that particular cytokine will be able to respond to it.
(Like dialing a particular number and only the person with that number can pick up)
Eg. Interferon

7

APCs

Antigen Presenting Cells

8

MHC

Major Histocompatibility Complex. Membrane proteins that serve as peptide display molecules for recognition by T lymphocytes. Two types: MHC class I and MHC class II.

9

ANTIGEN (Ag)

Any molecule(s) that can be specifically RECOGNISED as being foreign (via receptors) by B cells, T cells or Ab.
It may or may not induce an immune response.

10

EPITOPE

The portion of an antigen which is recognised (via receptors) and bound by immune system (B cells, T cells or an antibody).
Also referred to as "antigenic determinants"
3 categories:
- Isotype (constant region same within species)
- Allotype (constant region varies within species - multiple alleles)
- Idiotype (Variable region)

11

CLONAL SELECTION

The process by which particular lymphocytes (clones) are activated.
Antigen selectively causes activation, proliferation & differentiation of members of a clone of T or B cells that are specific for the antigen.

12

PHAGOCYTOSIS

The uptake of particulate materials by cells by engulfment.
STEPS:
1. Chemotaxis andAdherence
2. Pseudopodia encircle pathogen and fuse together, formation of phagosome which fuses with lysosome.
3. Ingested material is broken up into pieces and contents are eliminated via exocytosis.
*REMEMBER - some of the contents is retained and presented to T cells in the context of MHC II.

13

PHAGOCYTES

Cells with the capacity to internalise & degrade microbes or particulate antigens (neutrophils & macrophages are main phagocytes).

14

NEUTROPHIL

A phagocytic granulocyte involved early in the inflammatory response; most numerous WBC.

15

MACROPHAGE

Large mononuclear cells that phagocytose & kill micro-organisms, secrete cytokines & present antigens to T helper cells.

16

LYMPHOCYTE

A mononuclear leukocyte that mediates humoral or cell mediated immunity. Two types: B and T cells.

17

ANTIBODY (Ab)

Immunoglobulin (Ig), serum molecules produced and secreted by B cells (called plasma cells) in response to an antigen (Ag).
They are glycoproteins (A CHO component and a protein component)

18

COMPLEMENT

A group of serum proteins that participate in an enzymic cascade, ultimately generating the cytolytic membrane attack complex (MAC).
Major effector of HUMORAL branch of immune system because it is found in the serum component of blood.

19

PRIMARY IMMUNE RESPONSE

The immune response that is induced by INITIAL exposure to an antigen which activates naive B lymphocytes.
Mediated by IgM antibody.
Long lag phase (4-7 days)
Low to moderate Ab levels peaks at 7-14 days
So develops more slowly & to a lesser extent than secondary.

20

SECONDARY IMMUNE RESPONSE

The immune response that is induced by a SECOND exposure to antigen which activates memory lymphocytes.
Mediated by IgG
Shorter lag phase (1-2 days)
Higher Ab levels, peak in 3-5 days)
Ab levels sustained for longer.
So occurs more rapidly & is stronger than primary.

21

HAEMATOPOIESIS

The formation and differentiation of blood cells.

22

CLUSTER OF DIFFERENTIATION (CD)

A collection of monoclonal antibodies that all recognise an antigen found on a particular differentiated cell type or types. Basically any molecule that is on the surface of the cells.
It can be used to help identify abnormalities such as cells which are present in the blood when they should be in the bone marrow.

23

MONONUCLEAR PHAGOCYTE SYSTEM

(Also called Retinoendothelial System - RES)
Long lived phagocytic cells derived from bone marrow stem cells, found in many organs.
Include Monocytes and Macrophages.

24

FRUSTRATED PHAGOCYTOSIS

When Phagocytes attach to antigen/material that cannot be engulfed due to its size (usually something it shouldn't be attaching to such as the host tissue). Not a normal situation, usually in autoimmune situations.

25

M CELL

Specialized epithelial cells of the mucosa-associated lymphoid tissues. They transport antigens from the lumen to cells of the immune system, initiating an immune response

26

EFFECTOR CELL

The cell that makes a response and create enzymes such as perforin and macrophages.
Eg. NK Cells, Macrophages etc.

27

MALT

Mucosal Associated Lymphoid Tissue. It is an example of a non encapsulated lymphoid tissue. (Appendix, Peyer's Patches etc). They trap antigens entering through epithelial mucous membrane surfaces.

28

PAMPs

Pathogen Associated Molecular Patterns. They allow our immune cells to detect pathogens so they can migrate to the area and make things like cytokines. They are detected by PRRs (Pattern recognition receptors).

29

PRRs

Pattern Recognition Receptors.

30

TOLL LIKE RECEPTORS (TLR)

Important in 1st step of recognising invasion and doing something about it.
Without these, cells wouldn’t be able to engage with foreign pathogens.
Membrane spanning proteins that recognise pathogen associated molecules.
Found on a range of immune cells.
Each TLR recognises different pathogen molecules:
- TLR1 = mycobacteria (which causes TB)
- TLR4 = Lipopolysaccharide (found in gram negative
bacteria)

31

MAC

Cytolytic Membrane Attack Complex. The complex of complement components (C5-C9) which is formed in the terminal steps of either the classical or the alternative complement pathway and mediated cell lysis by creating a membrane pore in the target cell.

32

OPSINISATION

A process by which phagocytosis is facilitated by the deposition of opsonins (Ab or C3b) on the pathogen or particle. Promotes a stable adhesive contact.
It's like it makes the pathogen "more tasty" so killer cells won't walk past without eating it.

33

HEV

High Endothelial Venule. Typical of chronic inflammation (non-infectious). Regions in venules = Increased vasodilation and permeability. Components of blood always leaking into tissue. Heavy swelling and swelling doesn't go down.
Can be found normally in lymphoid organs but not in spleen.

34

APR

Acute Phase Response. It is a systemic response (different from inflammation) and involves entire body.
Characteristics such as fever, increased hormones, increased WBC production and acute phase proteins (Eg C reactive protein).

35

RESPIRATORY BURST

Metabolic process in activated phagocytes in which the rapid uptake of oxygen is used to produce reactive oxygen intermediates that are toxic to ingested micro-organisms.

36

ADCC

Antibody Dependent Cell-mediated Cytotoxicity.
A cell mediated reaction where non specific cytotoxic cells (that express Fc receptors - NK cells, neutrophils etc) recognise antibody to a target cell & cause lysis of that target cell.

37

ALTERNATE COMPLEMENT PATHWAY

Activation of complement that is initiated by the binding of C3b to foreign cell-surface constituents, such as microbial antigens; it is Ab independent and generates the membrane-attack complex (MAC), C3a and C5a and the opsonin protein C3b.

38

CHEMOTAXIS

Directional movement of cells up the concentration gradient of some chemotactic substances.

39

GRANULOMA

A tumour like mass or nodule that arises because of a chronic inflammatory response and contains many activated macrophages. Usually triggered by persistent infectious agents like mycobacteria.

40

HUMORAL

Pertaining to the extracellular fluids, including serum and lymph

41

INFLAMMATION

A tissue response to injury or other trauma characterised by 5 signs; heat, redness, swelling, pain and loss of function.

42

LGL

Large Granular Lymphocyte. A group of morphologically defined lymphocytes which are large and contain granules and function as NK cells.

43

LYSOSOME

A small cytoplasmic vesicle found in many cell types that contains hydrolytic enzymes, which play an important role in the degradation of materials ingested by phagocytosis & endocytosis.

44

NK CELL

Natural Killer Cell. A class of large, granular cytotoxic lymphocytes that do not have T- or B- cell receptors. They are Ab independent killers of tumour cells and virally infected cells and cal also participate in ADCC.

45

PHAGOLYSOSOME

A vesicle produced by the fusion of a phagosome and a lysosome following phagocytosis. Ingested material in the phagolysosome is digested by degradative enzymes of the lysosome.

46

PHAGOSOME

Intracellular vacuole containing ingested particulate materials; formed by the fusion of pseudopodia around a particle undergoing phagocytosis.

47

HAPTEN

It is a very small antigen that is too small to be immunogenic. When combined with a larger carrier molecule it becomes more immunogenic.