Show Menu
Cheatography
  1. Home >
  2. Education >

Immunology Revision Cheat Sheet by

yep!yep!yep!yep!yep!

Key Terms:

Immuno­logy:
Study of immunity (the response of the immune system to infection)
Immunity:
Ability of the host to protect itself against foreign organisms
Immune response:
A reaction of the body in response to the presence of a foreign substance (i.e. antigens)
Antigens:
Molecules from a pathogen or foreign organism that provoke a specific immune response

Spleen

1) Mounting immune response to antigens in blood stream
2) Large, ovoid organ situated high in left abdominal cavity
3) Surrounded by a capsule that extends a number of projec­tions (trabe­culae) into interior to form a compar­tme­nta­lised structure
4) Two types of compar­tments: red pulp and white pulp, which are separated by a diffuse marginal zone

Cellular basis of immunity

1) Immune cells:
 
1. Mononu­clear phagocytes
Monocytes and Macrop­hages
 
2. Dendritic cells
Langer­hans, Interd­igi­tating and Follicular
 
3. Granul­ocytes
neutro­phils, eosino­phils, basophils – help fight off infection
 
4. Lympho­cytes
B and T cells, NK cells

Primary Lymphoid Organs

1) Immature lympho­cytes generated in haemat­opo­iesis mature and become committed to a particular antigenic specif­icity within the primary lymphoid organs
2) Bone marrow: supports the maturation of all erythroid and myeloid cells in humans and mice, the maturation of B lympho­cytes
3) Thymus: unlike B lympho­cytes, T lympho­cytes do not complete their maturation in the bone marrow. T lymphocyte precursors need to leave the bone marrow and travel to the unique microe­nvi­ron­ments provided by the other primary lymphoid organ, thymus, in order to develop into functional cells

Eosino­phils

 
1) Comprise about 1-3% of total WBCs
2) Bi-lobed nucleus and acidop­hilic granules
3) Granules contain major basic protein
4) Produced by haemat­opo­iesis in the bone marrow and migrating into the tissues
5) Mobile and phagoc­ytotic
6) Mediate anti-p­ara­sitic response and type I hypers­ens­itivity reactions (allergy)

Basophils

 
1) Comprise less than 1% of total WBCs
2) Single lobed nucleus and heavily granulated cytoplasm
3) Non-ph­ago­cytic
4) Support mast cell function in tissues, mediate Type I hypers­ens­itivity reactions
5) Mast cells – cytopl­asmic granules that contains histamine, play an important role in allergic response

T-lymp­hocytes

 
1) Morpho­log­ically identical to B cells
2) Produced in bone marrow and mature in thymus
3) Mediated cell-m­ediated arm of adaptive response
4) Several sub-po­pul­ation exist: T helper cells (CD4), cytotoxic T cells (CD8) and Natural killer T cells (NKTs)
5) B and T cells form memory cells
  

Homeos­tasis and the Immune system

1) Pathogens invade organisms because they are seeking:
Source of food
 
Protection
 
Site for reprod­uction
2) Defense systems are evolved to get rid of the invading organisms

1. Mononu­clear phagocytes

 
Monocytes and Macrop­hages
1) Long lived phagocytic cells
2) Key initiators of inflam­mation
3) Involved in phagoc­ytosis or intrac­ellular killing of microo­rga­nisms
4) Can initiate an adaptive response
5) Found in blood (monoc­ytes) and tissues (macro­phages)

Secondary Lymphoid Organs

1) Located along vessels of lymphatic system
2) Distri­buted throughout the body and share some anatomical features
3) Some lymphoid tissues in the lung and lamina propria of intestinal wall consists of diffuse collec­tions of lympho­cytes and macrop­hages
4) Other lymphoid tissue is organised into structures called lymphoid follicles, which consist of aggregates of lymphoid and non lymphoid cells surrounded by a network of draining lymphatic capill­aries
5) Lymphoid organs are connected to each other and to infected tissues by blood and lymphatics

Macrop­hages

1) Terminally differ­ent­iated, long-lived monocytes residing in tissues
2) Like monocytes, macrop­hages are motile and highly adherent upon phagocytic activity
3) Serve different functions in different tissues
Phagoc­ytosis, Adaptive immunity, Muscle regene­ration, Limb regene­ration, Wound healing, Iron homeos­tasis – maintain constant concen­tra­tions of iron in the brain internal enviro­nment
4) Named according to their tissues location
eolar macrop­hages – lung
Histocytes - connective tissues
Kupffer cells – liver
Mesangial cells – kidney
Microglial cells – brain
Osteoc­lasts - bone

Natural Killer cells

 
1) Larger rim of cytoplasm
2) Cytotoxic cells that kill tumour and virus infected cells
3) Constitute 5-10% of lympho­cytes
4) Do not have membrane receptors for antigen but has NK cell receptors
5) Kill by releasing small cytopl­asmic granule of proteins (perforin and granzyme) -> cause host cells to die by apoptosis

B-lymp­hocytes

 
1) Small cells, thin rim of cytoplasm
2) Mature in bone marrow
3) Differ­entiate into plasma cells to secrete antibodies
4) Mediate humoral arm of adaptive immune response
5) B cells interact with T-helper cells which prolif­erate and switch to different sub-po­pul­ations
6) Plasma cells are terminally differ­ent­iated cells, many die in 1 or 2 weeks
  

Humoral Mediated Immunity

1) Cytokines – glycop­roteins that co-ord­inate immune response (inter­leu­kins, growth factors)
2) Antimi­crobial peptides - broad-­spe­ctrum anti-i­nfe­cti­ves­ ag­ainst wide ranges of bacteria
3) Complement – approx. 30 when activated promote bacterial cytolysis, phagoc­ytosis and inflam­mation
4) Acute phase proteins - contribute to acute response to infection by binding pathogens such as bacteria and facili­tating complement activa­tion 

Lymph cell

Lymphatic System

1) Immune system consists of immune cells that contin­uously circulate between blood and lymphoid organs
2) Lymphatic system consists of lymphoid tissues and organs and circul­ating clear fluid called lymph
3) Site of initiation of adaptive immune response

Neutro­phils

- Most abundant myeloid cell type, comprising 40-70% of total WBCs
- Multilobed nucleus and a granulated cytoplasm
- Produced by haemat­opo­iesis in the bone marrow that are released into the peripheral blood and circulate for 7-10 hours before migrating into the tissues, where they have a life span of only a few days
- Mobile and highly phagocytic
1) Major role in anti-b­act­erial response: ingest, kill, digest microbial pathogens
2) Contain multiple antimi­crobial agents, such as lysozyme (pepti­dog­lycan degrad­ation), hydrogen peroxide and lactof­errin (iron chelator)
3) Neutro­phils dying at the site of infection contribute to the formation of the whitish exudate called Pus

Dendritic Cells

1) Arises from hemato­poietic stem cells via different pathways and in different locations
2) Antigen presenting cells: Acquire antigen by phagoc­ytosis and display them to T cells
3) Langerhans cells: immature cells primarily found in skin and mucosal tissues
Accessory cells – 2 types
 
Interd­igi­tating dendritic cells
Mediate T cell activation and differ­ent­iation. Found in periphery and lymphatic tissues
 
Follicular dendritic cells
Unrelated to the above. Mediate B cell activation and differ­ent­iation. Restricted to lymphatic tissues.

Phagoc­ytosis

Inflam­mation accomp­anies an immune response

Our immune response includes innate and adaptive responses
  

The 5 Immuno­glo­bulin (Ig) Classes

Lympho­cytes

 
1) Consti­tutes 20-40% of WBCs and 99% of cells in lymph
2) Contin­ually circulate in the blood and lymph and are capable of migrating into tissue space and lymphoid organs
3) Subdivided into 3 classes
(a) B-lymp­hocytes
(b) T-lymp­hocytes
(c) Natural killer cells (NK cells)

Granul­ocytes

 
1) Contain cytopl­asmic granules
2) Also called polymo­rph­onu­clear leukocytes (PMN, PML, PMNL)
3) Produced via granul­opo­iesis in bone marrow
4) Based on cellular morpho­logy, cytopl­asmic staining charac­ter­istics, granul­ocytes are classified as
(a) Neutro­phils
(b) Eosino­phils
(c) Basophils

Lymphatic Continued

 
4) Lymphoid organs are either primary (central) or secondary (perip­heral)
5) Primary lymphoid organs:
Major sites of lymphocyte develo­pment i.e. thymus and BM
6) Secondary lymphoid organs:
Spleen, lymph nodes, mucosa­l-a­sso­ciated lymphoid tissues (MALT) including tonsils and Peyer’s patches

Monocytes

1) Comprise up to 10% of circul­ating WBCs
2) Motile and highly adherent upon phagocytic activity
3) During haemat­opo­iesis in the bone marrow, monocyte progenitor cells differ­entiate into promon­ocytes, which leave the bone marrow and enter the blood, where they further differ­entiate into mature monocytes
4) Monocytes circulate in the bloods­tream for about 8 hours, during which they enlarge; then migrate into the tissues and differ­entiate into macrop­hages and dendritic cells (Antigen presenting cells)

Lymph node

1) Sites where immune responses are mounted to antigens in lymph
2) Encaps­ulated bean shaped structures containing a reticular network packed with lympho­cytes, macrop­hages, and dendritic cells
3) First organised lymphoid structure to encounter antigens that enter tissue spaces

Effector mechanism

 
1) Proces­ses­ by­ wh­ich­ pa­tho­gen­s a­re ­des­tro­yed­ an­d c­lea­red­ fr­om ­the­ body
2) Can be both cell-m­ediated and humoral in origin
3) Cell-m­ediated – effector function is performed by a cell e.g. cytotoxic T cells (Tc), phagocyte, natural killer (NK) cell
4) Humoral – effector function is mediated by soluble molecules e.g. comple­ment, antibodies

Spleen Anatomy
           
 

Metadata

  • Languages:
  • Published: 29th April, 2025

Comments

No comments yet. Add yours below!

Add a Comment

Your Comment

Please enter your name.

    Please enter your email address

      Please enter your Comment.

          Related Cheat Sheets

          Drug Classes & Actions : NSAIDs Cheat Sheet

          More Cheat Sheets by MJC3

          IBD/ CROHN'S Cheat Sheet
          Gastrointestinal Physiology Cheat Sheet