43 Immune System Flashcards
(147 cards)
1
Q
What is the immune system functionally divided into?
A
The innate immune system and the adaptive immune system.
2
Q
How do the innate and adaptive immune systems differ in terms of their response?
A
The innate system recognises traits shared by a broad rang of pathogens using a few receptors.
The adaptive system is different in that it can learn and recognise individual pathogens.
Despite this the innate system is quicker as the adaptive system needs time to adapt to the specific threat.
3
Q
In what organisms are the innate and adaptive immunity systems seen?
A
All animals (and to some degree plants) have innate immunity whereas only vertebrates have adaptive immunity.
4
Q
What is the innate immune system divided into?
A
Barrier defences and internal defences.
5
Q
What are innate barrier defences?
A
Skin, mucus membranes, secretions i.e. basic to make skin inhospitable to bacteria
6
Q
What are the innate internal defences?
A
Phagocytic cells, “natural killer cells”, anitmicrobial proteins and the inflammatory response.
7
Q
What is adaptive immunity divided into?
A
Humoral response and cell-mediated response.
8
Q
What is the adaptive humoral response?
A
Antibodies that defend against infection in body cells.
9
Q
What is the adaptive cell-mediate response?
A
Cytotoxic cell that defend against infection of body cells.
10
Q
What is an insect’s exoskeleton composed of?
A
Chitin.
11
Q
Where besides the exoskeleton is chitin found in an insect?
A
In the intestines where it prevents bacterial invasion while still allowing nutrient absorption.
12
Q
What are the innate internal responses seen in insects?
A
They have immune cells called ‘hemocytes’ that travel round the hemolymph and attack bacteria etc. through phagocytosis.
Hemocytes also secrete chemicals that trap Plasmodium, the parasite carried by mosquitos that causes malaria.
Hemocytes and other insect immune cells can also secrete “antimicrobial peptides” that circulate and kill fungi and bacteria by disrupting their plasma membrane.
13
Q
Besides chitin, how is an insects digestive tract protected from bacteria?
A
Their intestines secrete Lysozyme, an enzyme that breaks down bacterial cells walls
14
Q
What organism causes malaria?
A
The par aside Plasmodium which is carried by mosquitos.
15
Q
How are fungal and bacteria cell walls distinguished by the innate immune system of insects?
A
Fungal cell walls contain certain unique polysaccharides, whereas bacterial cell walls have polymers containing combinations of sugars and amino acids not found in animal cells.
16
Q
How specific is the insect innate internl defence system?
A
Quite, it can recognise fungal cells walls using the protein-receptor “Toll” which is found on the plasma membranes of hemocysts, leading to specific anti-fungal antimicrobial peptides
Bacterial infection leads to the triggering of different responses and thus antibacterial peptides.
17
Q
What is an example of a fungus that infects flies?
A
Neurospora crassa
18
Q
What is an example of a bacterium that infects flies?
A
Micrococcus luteus,
19
Q
What does the innate barrier defences of vertebrates include?
A
Epithelial cells and mucus membranes that line the digestive, reproductive and respiratory tracts.
Tears, saliva and mucus also include Lysozymes, which are enzymes that break down the cell walls of bacteria etc.
Stomach acid also breaks down bacteria etc. in food.
Secretions from oil and sweat glands give human skin a pH ranging of 3 to 5, acidic enough to stop bacterial growth
20
Q
How does mucus act as a barrier defence?
A
It traps bacteria which are then swept away by cilia.
21
Q
How are the innate cellular response of vertebrate regulated?
A
With receptors named “Toll-like receptors” (TLR) that bind to common component of bacteria.
22
Q
What are some examples of specific toll-like receptors in vertebrates?
A
TL3 is in the inside membrane of vesicles to detect double-stranded RNA characteristic of viruses.
TR4 on the plasma membranes of immune cells recognises lipopolysaccharide which are found on many bacteria.
TLR5 detects “flagellin”, the main component of bacterial flagella.
23
Q
What happens after a toll-like receptor detects a microbe?
A
Endocytosis occurs, trapping the microbe in a vacuole. The vacuole fuses with a lysosome. The lysosome contains gasses that poison the bacteria and enzymes that break it down.
The debris format the bacteria is then released through endocytosis.`
24
Q
What are main phagocytic cells of the vertebrate innate immune system?
A
Neutrophils and Macrophages.
25
How do neutrophils and macrophages differ?
Neutrophils are smaller an circulate the blood,
Macrophages are much large so some circulate the blood while others reside permanently in organs where they are likely to encounter pathogens.
26
Where do many macrophages reside and why?
In the spleen as this is where many blood pathogens are trapped.
27
What are the less common phagocytic cells of the vertebrate immune system?
Dendritic cells and eosinophils.
28
What are dendritic cells?
Phagocytic cells typically found on the skin. They are port of the adaptive immune system
29
What are eosinophils?
Immune cells that are found under mucus surface and that are not as active at phagocytosis.
They primarily defend against large invaders such as parasitic worms which they kill by secreting enzymes.
30
Besides phagocytic cells, what type of cells are part of the vertebrate innate cell-mediated immune system?
Natural killer cells.
31
What are natural killer cells?
Cells that detect microbes by analysing key component and then release chemicals that kill the bacterium etc.
32
What immune defences are seen in the lymph vessels?
Some macrophages reside in the lymph nodes.
Dendritic cells reside outside the lymph system but migrate to the lymph nodes when they interact with bacteria.Within the lymph nodes, dendritic cells interact with other immune cells, stimulating adaptive immunity.
33
Besides cells, what is secreted as part of the innate immune system of vertebrates?
Antimicrobial peptides and proteins.
34
What is an example of an innate-defence antimicrobial protein?
Interferons which provide innate defences against viruses.
35
What causes the release of interferons?
Virus-infected body cells secrete it to trigger nearby uninfected cells to secrete substances to protect themselves.
Some white blood cells secrete a different type of interferon that activates macrophages to enhancing their phagocytic ability.
36
Besides interferons, which antimicrobial proteins are released?
The "complement system", which consist of roughly 30 blood plasma proteins with immune properties.
37
How does the “complement system” work?
The antimicrobial proteins circulate the blood in their inactive forms. They are activated by substance on the surface of the microbes.
When they identify a microbe they destroy it by catalysing a cascade of reaction that results in lysis (bursting) of the cell.
38
What is an important innate response to infection
The inflammatory response.
39
What causes the inflammatory response?
The signalling molecule histamine is store in the granules (vesicles) of “mast cells” which are located in connective tissue.
Damage to this tissue causes the release of this histamine which triggers nearby blood vessels to dilate causing more antimicrobial peptides to arrive. Activated macrophages and neutrophils release cytokines which signal good flow to increase.
Complement proteins are also attracted and after being activated trigger more histamine release.
40
Why is the inflammatory response important?
It attracts macrophages and neutrophils etc. to consume bacteria and digest the cell debris. Increased blood flow also ‘recruits’ more antimicrobial peptides.
41
What is an immune response across the body called?
A “systemic” response as opposed to inflammation, which is local.
42
What are some example of systemic responses?
Injured/infected cells send signals to the bone marrow stimulating more neutrophils and other white blood cells to be released.
Also fever.
43
What is fever?
A systemic response in which the body raises its own “thermostat” i..e intentionally becomes hotter.
44
What is the advantage of raising the temperature during fever?
It is believed to improve phagocytosis and by speeding up chemical reaction accelerate tissue repair.
45
What is an excessive systemic inflammatory response?
Septic shock, often the result of bacterial infection, leads to a very high fever, low blood pressure and poor blood flow through capillaries.
46
What does “chronic” refer to with regard to a disease?
Ongoing even when the cause is gone i.e. pain after injury has healed?
47
What disease are caused by chronic inflammation?
Crohn’s disease and ulcerative colitis, both of which occur when unregulated inflammatory respond disrupts intestinal function.
48
How have bacteria adapted to avoid phagocytic destruction?
Some have an outer capsule that disrupts molecular recognition.
Some bacteria, such as those that cause TB, can survive in lysosomes and thus are essentially hidden from the immune system.
49
What are the basic cells of the adaptive immune system?
B cells and T cells.
50
How are B and T cells produced?
In the bone marrow they both develop from stem cels. Some migrate the “thymus”, an organ above the heart, and develop into T Cells.
Those that remain in the bone marrow develop into B Cells.
51
What is a substance that elicits an adaptive-immune response called?
An antigen
52
How are antigens detected?
By “antigen receptors” of the plasma membranes of B and T cells.
53
How does antigen reception differ from “Toll-like receptors”?
They are extremely specific to the point they respond to specific bacteria species.
54
How many types of antigen receptors are there and how many different kinds does one B/T cell have?
There are millions of different antigen receptors but each B/T cell only has one type.
55
Note:
Antigens are often proteins or polysaccharides
56
Where are the antigens located?
Many are on the plasma membrane of the bacteria etc. or are a particular part of the first
Some are products secreted by microbes.
57
How does the antigen bind to the antigen receptor?
A specific region of the antigen, known as the “epitope” binds to a specific region of the antigen receptor.
58
What is an epitope also called?
An “antigenic determinant”
59
What is the structure of a B cell antigen receptor?
There are two heavy chains, both start parallel then one branches to the left and the other to the right. The two chains are linked by disulphide bridges to form a Y shape.
Each side of the Y shape i.e. \ and / has a parallel light change bonded to it by a disulphide bridge.
The light and heavy chains both have constant regions but end in a variable regions with an Antigen-binding site on each end (total:2).
The heavy chains extend slightly into the cytoplasm.
60
What happens when a B cell binds to an antigen?
The B cells causes more cells to form, all of which release antibodies.
61
What are antibodies also known as?
Immunoglobulin or Ig
62
What are antibodies?
A soluble form of the antibody receptor that is released into the blood/lymph etc. on its own so that it can bind to more antigens.
63
What is the structure of antigen receptors of T cells?
They have two parallel chains that extend partly into the cytoplasm. On chain is the α-chain and the other is the β-chain. These chains are joined by disulphide bridges and have a constant region at the base and a variable region with a tip that acts as an antigen binding cells. The parallel chains act together to form a single antigen binding site.
64
What form of lymphocyte has a T shaped antigen receptor?
B cells (not T cells.)
65
How do B cells and T cells differ in terms of the antigens they act on?
B cells act on antigens that float through the blood/lymph either as secreted products or on the surface of bacteria etc.
T cells act on antigens that are presented by infected cells on that cells plasma membrane.
66
How does antigen presentation occur?
When a cell is infected by a bacteria etc. it takes and antigen off the bacteria that identifies it. It then breaks this antigen down into small amino acids called ‘antigen fragments’
These antigen fragments bind to MHC (major histocompatibility complex) molecules that are placed on the plasma membrane of the infected cell so the T cell can identify them.
67
What are there more of: unique B cell antigen receptors or unique T cell antigen receptors?
T cell antigen receptors.
68
How are so many different antigen receptors made?
Each antigen receptor has a variable region which in turn consists of up to 40 different V (variable) segments and unto 5 J (joining) segments.
Each of these segments can be made of a vast number of unique J/V segment ‘blocks’ and which are joined together to make an almost unique antigen receptor.
69
How are antigen receptors synthesised?
A DNA sequence contains the sequences of many alternative V and J regions.
An enzyme complex called “recombinase” randomly splices the genetic material leading to many combinations of V and J regions.
70
Why don’t antigen receptors typically elicit a response to the bodies own cell?
Due to the random rearrangement of V and J segments, some B/T cells will have antigen receptors that would lead to an autoimmune response.
To rectify this in the bone marrow/thymus the mature B/T cells are exposed to some typical epitopes of human cells. Any that react are killed through apoptosis or otherwise rendered non-functional
71
What is the property of the immune system to not attack cells of its own body?
Self-tolerance
72
How are B and T cells specific to an encountered disease proliferated?
An antigen is presented to a steady stream of lymphocytes in the lymph nodes, if one lymphocyte has an antigen receptor for this antigen it proliferates through clonal selection.
73
What happens during clonal selection?
The B/T cell divides rapidly, forming an identical clone.
Some of the daughter cells develop into Memory cells which are long-lived and stored as a reserve against future attacks as if they encounter the same antigen again they can produce more B/T cells through clonal selection.
Others daughter cells become effector cells that take immediate action by releasing antibodies for that antigen.
B cells and T cells develop into different types of effector cells but both develop into memory cells (B memory cells and T memory cells)
74
What is the effector cell forms of B cells?
Plasma cells
75
What is the effector cell form of T cells?
Cytotoxic T cells and helper T cells
76
What property do memory cells lead to?
Immunological memory.
77
In term of immunological memory, what can immune responses be classed as and what are these forms?
The PRIMARY immune response is the first time the antigen is encountered.
If it is encountered again the antigen elicits the SECONDARY response from the memory cells. This response is faster, more prolonged and of a greater magnitude as the body is “ready"
78
How does the ability of an organism to elicit a secondary response change over time?
It will yield the greatest secondary immune response if the antigen is encountered again 2-7 days after the primary response.
While the memory cells and thus secondary response to a specific antigen does degrade it remains useful throughout the organism’s life span
79
What releases histamine in the immune response?
Mast cells.
80
What are the forms of adaptive immunity?
Humoral and cell-mediated
81
How does humoral and cell mediated adaptive immunity differ?
In the humoral immune response antibodies neutralise and eliminate pathogens and toxins.
The cell-mediated immune response uses T cells to destroy normal cells that have been infected by pathogens.
82
What immune response are helper T cells involved in?
Both the humoral and cell mediated responses.
83
How do helper T cells mediate the immune response?
If they detect antigens that have been presented they release signals that direct other cells to initiate antibody production?
84
What type of cells can be antigen presenting cells?
Dendritic cells, macrophages and B cells as well as the actual infected cell.
85
How does antigen presentation differ between infected body cells and from dendrite cells, macrophages or B cells?
Most body cells have only class I MHC molecules, but antigen-presenting cells have both class I and class II MHC molecules. The class II molecules identifies the antigen-presenting cell.
86
What happens when a T cell’s antigen receptor detects a presented antigen?
The T cells firmly binds to the cell using its antigen receptor and an accessory protein named CD4.
This causes the antigen presenting cell to secrete release Cytokines. These chemicals trigger the helper T cell to clone itself into more helper T cells.
The helper T cells then release other cytokines which activate B cells and cytotoxic T cells.
87
When activated by helper T cells, how do B cells and Cytotoxic T cells differ in their response?
The B cells are part of the humoral response so secrete antibodies from plasma cells.
The T cells are part of the cell-mediated response so attack infected cells.
88
What are the effector cellos of the cell mediated response?
Cytotoxic. T cells.
89
How do cytotoxic T cells kill infected cells?
They bind to the infected cell’s "class 1 MHC-antigen fragment complex” (only infected cells present these, not ‘good’ immune cells. ) This binding is made using the T cell’s antigen receptor and an accessory protein name CD8.
The cytotoxic T cells releases perforin molecules which form pores in the infected cell’s plasma membrane. The cytotoxic also inserts granzymes into the infected cell which enter using endocytosis.
The granzymes are enzymes which break down proteins and initiate apoptosis in the infected cell. The cytotoxic T cell is released so that it can kill other cells that present the same antigen.
90
Which cells present antigens to Helper T cells?
Both phagocytic and infected cells.
91
Can cytotoxic T cells be reused?
Yes, they are released after the infected cell undergoes apoptosis.
Since they have specific antigen receptors they can only target other cells infected with the same pathogen and thus that present the same antigen.
92
What antigens can macrophages, dendritic cells and B cells present?
Macrophages and dendritic cells can present any antigen fragments,
B cells only present antigen fragments of the specific antigen they have receptor for.
93
How do B cells present antigen?
When an antigen binds to a B cells its uses receptor-mediated endocytosis to bring in a few foreign molecules.
The class II MHC protein of the B cell then presents these antigen fragments to a helper T cell.
94
What activates B cells?
The cytokines released by helper T cells?
95
What happens when B cells are activated?
They divide and differentiate into Memory B cells and Plasma cells.
The plasma cells stop producing the membrane bound antigen receptors and instead secrete these receptors into the body fluids as “antibodies"
96
What type of immune cell are plasma cells?
B cells.
97
In what basic ways do antibodies lead to the destruction of pathogens?
Neutralisation, opsonisation and by activating the complement system and pore formation
98
What is neutralisation in terms of antibodies?
The antibodies bind to key proteins etc. on the surface of viruses and toxins etc. that are in the body fluids
By binding to viruses they prevent them from being able to attack the host. Similarly binding to toxins in the blood/lymph makes these toxins unable to enter the cell and damage it.
99
What is opsonisation?
By binding to the bacteria etc. the antibodies released by the plasma cells mark that bacterium etc. for phagocytosis by macrophages and neutrophils.
100
Why do cytotoxic T cells form pores in their target cells?
This allows water to rush in causing the cell to swell and lys (burst)
101
How are antibodies activate the complement protein system?
The antibodies bind to antigens on the surface of the infected cell. This activates “complement proteins” which form a “membrane attack complex” on the infected cell’s plasma membrane.
The “membrane attack complex” causes pores in the infected cells’s plasma membrane causing water to rush in and thus the cell becomes lysed.
102
Why is opsonisation important in terms of regulating B cells?
Opsonisation caused by B cells triggers the phagocytosis of the pathogens. The macrophage or neutrophil then present this fragment causing a helper T cell to be activated and thus more B cells and cytotoxic T cells.
In this way through positive feedback opsonisation increases the release of B cells.
103
How can antibodies become involved in cell-mediated immune response?
If a virus uses the cell’s biosynthetic machinery to produce viral proteins these will appear of the plasma membrane of the infected cells.
Antibodies can bind to these viral proteins and thus recruit “natural killer cells” to kill the infected cell.
104
What are the forms of antibodies?
IgD, IgM, IgG, IgA and IgE (DA GEM)
105
How does the forms of immunoglobulin differ?
The B cell antigen receptors are made of IgD, which is membrane bound. The other forms are released as soluble antibodies.
106
What is the most common form of immunoglobulin in blood?
IgG.
107
How is the fetus/child given immune protection? How does this differ from how the mum gets immunity?
The mum gets immunity from “active immunity” as her immune cells actively kill cells and secrete antibodies.
The fetus gets “passive immunity” from antibodies that circulate through it from the mum. This is different from “active immunity” as the fetus has immunological memory of a pathogen it has not previously encountered. These circulating antibodies are in the form of IgG.
When the child is born it still gets “passive immunity” from the mother in the form of IgA antibodies in breast milk.
108
How do tears, saliva and mucus protect the body form infection?
Besides operating as part of the innate immune system these fluids also contain IgA antibodies to protect against pathogens and toxins.
109
Where is IgA found?
In breastmilk to give infants “passive immunity”
Also in tears, saliva and mucus to protect the body form infection.
110
How does immunisation worK?
Antigens are introduced in a form that will not cause the actual disease i.e. dead bacteria. The immune system still elicits a response to these foreign particles so memory T cells are still formed and thus long-term immunity is provided incase the body ever reencounters that antigen.
111
What is the term for a drug that counters the effect of venom?
An antivenin (NOT antivenOm)
112
How do antivenins work?
Sheep/horses are injected with a small amount of venom. This leads them to produce antibodies which are then preserved in the antivenin.
113
What can antibodies used for therapeutic use be classed as? How do they differ?
Monoclonal antibodies are all produced form a single clone plasma cell and thus all react to the same antigen.
Polyclonal antibodies are made from cultures of many plasma cells and thus react to a range of antigens.
114
How do pregnancy kits work?
They use monoclonal antibodies to detect “human chorionic gonadotropin” (hCG) which is releases when the embryo implants in the uterus.
115
In plasma cells, what organelle is enlarged and why?
The ER which takes up much of the cel’s space so that secretion can occur.
116
How do blood cells differ between blood groups?
People with blood type A have A carbohydrates on the plasma membrane of the red blood cell and people of blood type B have B type carbohydrates.
Blood type O red blood cells have neither and AB red blood cells have both.
117
Why does transfusion of the wrong red blood cells lead to illness?
The B and T cells that mature in the bone marrow/thymus are trained not to target their own cells. Thus in a blood type A individual the immune cells will not react to the A type carbohydrate.
If however blood with B carbohydrates in introduced the B/T cells will not have been selected not to kill it so they will trigger an immune response, leading to illness.
118
What are the symptoms of incorrect blood transfusion?
The transfused red blood cells undergo lysis, which can lead to chills, fever, shock, and kidney malfunction.
119
Why can tissue and organ transplants lead to rejection?
Each person have a unique combination of the vast number of similar but different MHC molecules.
The more difference in the MHC molecules between people, the less of a match they will be.
120
What are bone marrow transplants often used for?
Many diseases including leukaemia.
121
What is organ transplantation rejections specifically called?
graft versus host reactions.
122
How are patients prepared before receiving bone marrow transplants?
Radiation is used to kill the patients existing bone marrow so that it will not lead to an immune reaction of the new marrow.
123
What conditions are caused by a malfunctioning immune systems?
Allergies, Autoimmune diseases and Immunodeficiency diseases.
124
What are substances that causes allergies called?
Allergens
125
How are allergic responses triggered?
IgE antibodies are formed by plasma cells upon first encountering the allergen.
These antibodies bind to receptors on mast cells as a form of immunological memory.
If the allergen is encountered again these antibodies on the mast cell bind to the allergen. Cross-linking of adjacent IgE receptors wherein they both bond to the same allergen particle leads to the release of “histamines” from the “granules” of the mast cell. These histamines travel round the body and lead to allergy symptoms.
126
Where are mast cells located?
In connective tissue.
127
How can allergy symptoms be improved?
With antihistamines that block the RECEPTORS for histamines.
A shot of epinephrine (Epi pens) can mitigate anaphylactic shock.
128
What occurs during anaphylactic shock?
The peripheral blood vessels dilate causing a drop of blood pressure and thus less blood flow to the brain etc. . The bronchioles are also constricted, leading to asphyxiation.
129
What is lupus?
An autoimmune disease in which the body releases antibodies against the histones and DNA released during the normal breakdown of cells.
130
What class of disease is rheumatoid arthritis and what does it cause?
An autoimmune disease that leads to the swelling of joints.
131
How does type 1 diabetes occur and thus what type of disease is it?
The insulin producing beta cells of the pancreas are attacked by autoimmune cytotoxic T cells.
132
Where is insulin produced in the pancreas?
By beta cells.
133
What is the most common neurological disease and what causes it?
Multiple sclerosis in which T cells destroy the myelin sheaths of the central nervous system. Therefore this disease, which can lead to paralysis, is autoimmune.
134
What are immunodeficiency diseases classed as and how do they differ?
"Inborn immunodeficiency" is immunodeficiency present at birth whereas “acquired immunodeficiency” is acquired later in life.
135
What is an example of an “inborn immunodeficiency” and how does it affect the immune system?
In “severe combined immunodeficiency” (SCID) functional lymphocytes are either rare or absent.
136
How can acquired immunodeficiency arise?
Cancers like Hodgkin’s disease, AIDS and also drugs used to treat autoimmune disease.
137
How can immunodeficiency lead to cancers?
Some cancers are triggered by viruses and thus if the immune system is unable to kill theses viruses the cancers are more likely.
138
What are some example of viruses that cause cancers.
Herpesvirus --> Kaposi’s sarcoma
Hepatitis B virus --> liver cancer
human papillomavirus (HPV) --> cervical cancer
139
What are some evolutionary mechanisms employed by viruses to combat the immune system?
Antigenic variation, Latency and attack on the immune system.
140
What is antigenic variation?
The bacterium etc. randomly varies the proteins on its plasma membrane so that each time it infects the host it has a different antigen and thus render immunological memory ineffective.
141
What are some examples of pathogen that employ antigenic variation?
The influenza virus as it rapidly mutates leading to new strains with different antigens.
Also the parasite that causes sleeping sickness (trypanosomiasis)
142
Why was the 1918 influenza outbreak so lethal?
The human flu virus exchanged genes with another influenza strain that infected a different kind of animal (like swine flu which exchanged with pigs). This lead to different antigens being presented i.e. antigen variability.
Since these genes originated from the animal influenza they where vastly different form the antigens typically seen in human diseases, making the release of the correct B/T cells slow.
143
What is latency in terms of a mechanism used by pathogens to avoid detection?
The virus enters a dormant state called “latency” after infecting the host. Since they stop making viral proteins they can not be easily detected by the immune system.
If the individual becomes immunocompromised such as after catching the flu, the ensuing fever triggers the virus to remerge and more easily spread. Even emotional stress or menstration can awaken the virus
144
What is an example of a virus that uses “latency”?
The “herpes simplex" virus which becomes latent in sensory neurons. Since theses sensory neurone produce little MHC I molecules they are not good at presenting antigens and thus make the virus even harder to find.
145
What are forms of herpes?
Herpes type 1 which leads to mouth sores. Herpes type 2 lead to genital sores.
146
What is "passive immunity"?
The adaptive immune response fetuses and infants have due to IgG they review from placental blood and and the IgA breast milk respectively.
Note that this means that they in affect have immunological memory to pathogens they have not yet encountered.
147
What is Trypanosomiasis?
"Sleeping sickness"
