Immunology PDF

IMMUNOLOGY Components of Blood
Blood is a complex mixture made up of blood cells suspended in a liquid. The liquid portion is known as plasma.
Plasma constitutes more than half of the blood’s volume and is comprised of ions, minerals, glucose, dissolved proteins and gases.
The dissolved...

IMMUNOLOGY Components of Blood
Blood is a complex mixture made up of blood cells suspended in a liquid. The liquid portion is known as plasma.
Plasma constitutes more than half of the blood’s volume and is comprised of ions, minerals, glucose, dissolved proteins and gases.
The dissolved proteins found in blood includes albumin (the most abundant), antibodies and clotting factors
The blood cells include erythrocytes (red blood cells) leukocytes (white blood cells) thrombocytes (platelets) Components of Blood
The erythrocytes are the most abundant cells found in the blood.
The thrombocytes are cell fragments and are smaller than both the erythrocytes and the leukocytes. They are present in the blood at an approximate ratio of 1 thrombocyte: 20 erythrocytes
Serum is plasma without the clotting factors Blood cells http://www.pennmedicine.org/health_info/images/19192.jpg Components of Blood
Leukocytes are found less numerous than erythrocytes in the blood with an approximate ratio of 1 leukocyte : 700 erythrocytes.
They play a major role in the immune system and act primarily in defending the body against infection
The leukocytes are divided into two groups depending on the structure of the cells. Leukocytes
(a) Granulocytes - These white blood cells have granules in their cytoplasm. They are referred to as polymorphonuclear leukocytes (PML) due to the varying lobed shaped nucleus present in these cells. Examples of granulocytes include, basophils, eosinophils and neutrophils
(b) Agranulocytes: These white blood cells have no granules in their cytoplasm. Examples of agranulocytes include lymphocytes and monocytes. Classification of Leukocytes http://www.lymphomation.org/images/leukocytes-normal.gif Granulocytes
The cytoplasm of the cell contains granulocytes
There are 3 types neutrophil, eosinophil and basophil
Neutrophils: the most abundant granulocyte. They play a role in fighting infection by killing microorganisms and foreign matter. They are predominant in inflamed tissues and pus
Eosinophils: are usually associated with allergic diseases e.g. Hay fever and eczema; and infections from parasites such as worms.
Basophils: are the least common. They are involved in inflammatory reactions in your body, especially those related to allergies and asthma. Agranulocytes: Lymphocytes
The lymphocytes are the main constituents of the immune system and are found mainly in the lymphoid tissues and organs. They yield antibodies which arrange themselves on the cell membrane. They are therefore specific and recognizes complementary antigens
There are three types of lymphocytes that exist. They include the B- cells, T - cells and natural killer (NK) cell Agranulocytes: Lymphocytes – B cells
B cells are responsible for antigen interaction, antibody production and immune memory
They have a B cell receptor (BCR) on their surface that binds to a specific antigen Agranulocytes: Lymphocytes – T cells
They have antigen specific receptors called T cells receptors (TCR)
The antigens are presented to the T cells by antigen presenting cells (APC) e.g. macrophages and B cells
There exist two type of T cells, depending on the receptor on the surface i.e. CD4 and CD8 cells CD4 cells Th1 Th CD4 Th2 TD
Th1 (helper cells) - activate macrophages to destroy pathogens
Th2 – stimulate B cells to produce antibodies
TD (delayed type hypersensitivity cells) - activate phagocytes CD8 cells Tc CD8 Ts
Tc (cytotoxic T cells) – directly kill cells with antigens on the surface
Ts (suppressor cells) – regulate immune response by suppressing action of the B cells Agranulocytes: Lymphocytes – T cells
In the thymus T cells differentiate into helper T cells (TH cells), cytotoxic T cells (Tc cells)and the suppressor T cells (Ts cells)/ regulatory cells.
The TH cells secrete cytokines that stimulate B- cells to produce plasma cells and memory cells, thus promoting antibody production. The TH cells also activate macrophages to destroy pathogens.
The Tc cells kill cells with antigens on its surface… damaged and dysfunctional cells. The antigens are presented to the T cells by antigen presenting cells (APC) e.g. macrophages and B cells
Ts cells regulate immune response by suppressing the action of the B cells Agranulocytes: Lymphocytes – N K Cells
The NK cells protect against infection. They are able to kill and ingest pathogens and foreign matter Agranulocytes: Monocytes
The monocytes are produced by the bone marrow, they play a part in the immune system by protecting the body against blood borne pathogens
They migrate in the blood and are then stored in tissues where they differentiate into macrophages and dendritic cells
They are phagocytes as a result they are able to engulf, kill and digest pathogens. The monocytes become attracted to these pathogens due to the antibodies that are present on their surface. This is referred to as antibody mediated cellular toxicity Common Terms in Immunology
Immunity -This is having a biological defense to fight infections and diseases
Antibody (immunoglobulins) – are proteins found in biological fluids. They identify foreign matter (antigens) and eliminate them
Antigen – a molecule that is recognized by an antibody or T cell receptor
Immunogens - substances that induce an immune response N.B. all immunogens are antigens but not all antigens are immunogens
Haptens – These are small molecules that are recognized by an antibody but is unable to elicit an immune response by itself, i.e. they are not immunogenic
Vaccines - They stimulate the immune system to produce antibodies without having to become infected with the disease Immunology
This is the study of the immune system
The function of the immune system is to act as a defense against infections by bacteria, fungi, parasites
Immunity can be divided into two groups
(a) Innate Immunity (b) Specific Acquired Immunity Innate Immunity
This is immunity that is naturally present and does not require prior sensitization to an antigen
There exists barriers that helps to prevent infection, these include the skin, mucous membrane, secreted fluids etc. Innate Immunity: Skin
Major line of defense
When intact it is impermeable to most infectious agents
Sweat and sebaceous secretions contain lactic acid and fatty acid. The low pH inhibits bacterial survival Innate Immunity: Mucous Membrane
The mucous secreted prevents bacteria from adhering to the epithelial cells
The particles that are trapped can be removed by sneezing, coughing, ciliary movement Innate Immunity: Secreted Fluids
These contain bactericidal agents e.g. Fluid Bactericidal agent Gastric juice Acid Semen Zinc Tears Lysozyme Innate Immunity: Bacterial Antagonism
This deals with the existence of harmless bacteria that will compete with pathogens for essential nutrients thus inhibiting growth …e.g. yeast infection Innate Immunity: Contact with Phagocytes
If microorganisms penetrate the body they are destroyed by a process called phagocytosis
Phagocytes will engulf and digest the remains of invading pathogens
They contain fluids that will destroy pathogens Fluids in phagocyte Effect Lysosyme Attacking the peptidoglycan in cell wall of bacteria Protease Breaks down proteins Affects enzyme function nuclease Breaks down nucleotides Innate Immunity: Contact with Phagocytes
The breakdown of pathogens generate antigens which then triggers an immune response
Phagoctes are found in body fluids and tissues
Major phagocytic cells are (a) dendritic cells: Found in the skin, mucous membrane, lungs and spleen They are antigen presenting cells (b) macrophages: Obtained from white blood cells called monocytes Macrophages attack anything that is not a part of the body e.g. pathogens, cancer cells and damaged tissues (c) natural killer (NK) cells: Target abnormal cells They release proteins called perforins that perforate the target cell membrane (d) neutrophils and eosinophils Acquired Immunity
This occurs when a person is exposed to an infectious agent or live pathogen and develops a disease
Acquired immunity can be subdivided into active and passive immunity Passive Immunity
Transmitted by antibodies or lymphocytes from another host (Immunization)
It is available right away
However it has a short life span – the antibodies produced can be broken down naturally and are not stored
Can develop hypersensitivity to drugs administered Passive Immunity: Naturally Acquired
Passive immunity can be acquired naturally, e.g. the transfer of antibodies from mother to fetus during pregnancy
A newborn baby has passive immunity to measles, rubella, mumps from antibodies passed through the placenta from the mother
The immunity lasts for approximately a year
Therefore MMR has to be given after the first birthday Passive Immunity: Artificially Acquired
Passive immunity can also be acquired artificially and is admin. in the form of an injection
It is given when there is a recent outbreak of a disease or emergency treatment to poisons from insects
Antibodies are obtained from animals and injected into humans Active Immunity
This occurs when a vaccine is used to trigger the immune system to produce antibodies
The individual is given the actual microbe, antibodies are produced and stored
When the immunized person comes in contact with the disease
The immune system will recognize it and produce antibodies
The advantage is that the resistance is long term
Disadvantage – resistance can be slow Immunology Immune Response
Characteristics of immune response includes (a) Specificity – that is the ability to distinguish among target molecules and to respond to each individually (b) The ability to distinguish between self and non self molecules preventing autoimmune diseases (c) It relies on memory Primary Immune Response
When exposed to an antigen for the first time the immune response is slow
The virgin cells will produce activated cells and memory cells
After this lag period antibody production is rapidly increased and then gradually decreases to low levels Secondary Immune Response
Upon second exposure to the antigen, the lag period is significantly shorter
This is because the memory cells respond more rapidly than the virgin cells
Antibody production is greater and more rapid than before Immune Response
Immune response can be antibody mediated (production of antibodies) or cell mediated (production of specialized cells that are able to kill pathogens) Antibody Mediated Response/ Humoral Response
When a pathogen enters the body it first interacts with the innate immune system
Once it is able to penetrate these defenses it comes in contact with the acquired immune system
The pathogen is taken up by macrophages and B cells with matching receptors
The antigen will be on the surface of these cells where it forms a complex with the major histocompatibility (MHC) protein
The antigen-MHC protein then complexes with the helper T cells…the antigen is recognized by the T cell receptors (TCR) Antibody Mediated Immune Response/ Humoral Response
The MHC-antigen-TCR complex produces molecules called cytokines
The cytokines produced activates the B cell to produce plasma cells and memory cells
After the first exposure to an antigen the B cells divide into plasma B cells (which produce antibodies) and memory cells
After the second exposure to the antigen, the memory cells proliferate and produce plasma B cells and more memory cells
Plasma B cells have a shorter life span than memory cells http://nobelprize.org/educational_games/medicine/immunity/images/detail/series.gif Cell Mediated Immune Response
Macrophages engulf and digest invading pathogens
The macrophages will present the antigens on their surface to get the attention of the helper cells
Only helper T cells with matching receptors will be activated and will interact with the macrophages
T H cells will proliferate and release chemicals activating the Tc cells. The Tc cells with matching receptors will be activated and clones made
The Tc cells will attack infected macrophages releasing toxins and killing the cell THE EFFECT OF ENVIRONMENTAL FACTORS ON THE IMMUNE SYSTEM 
The immune system helps us to fight infections caused by fungi, bacteria and viruses
An impaired immune system weakens the ability to fight infection and cancer causing agents
In response to an infection the immune system causes pain, fatigue, weight loss and fever e.g. fighting influenza virus that causes flu 
Maintaining a properly functioning immune system is important in healthy living
There exist 4 factors that significantly affects the immune system.
These include (a) Aging (b) Nutrition (c) Exercise (d) Stress Aging
The skin is the first line of defense
As we get older the skin starts breaking down leading to the development of fine lines and wrinkles
In postmenopausal women, the fat layer under the skin becomes thinner and the skin loses its elasticity due to hormonal changes
As a result the skin becomes more vulnerable to cuts and abrasions.
Skin conditions associated with aging includes (a) dermatitis (d) varicose veins (b) skin lesions (e) leg ulcers (c) shingles Aging
As we get older the ability to fight infection is significantly decreased. The process is also less efficient
The ability to produce lymphocytes (cells that produce antibodies) is significantly reduced
The configuration of the lymphocytes and their reaction to infection changes
The cells are less vigorous and less effective in fighting infection Aging
When the antibodies are produced the duration of the response is shorter than in younger individuals
Elderly individuals that is 70 > yrs. old tend to produce autoantibodies that attack their own cells
This can lead to the development of rheumatoid arthritis, atherosclerosis and myocardial infarction Nutritional Status
Proper nutrition is responsible for proper functioning of the immune system
Underweight individuals are at greater risk of getting an infection
Reducing calorie intake to 1200 kilocal. per day can also lead to a reduction in the immune function
In young healthy individuals, taking supplements does not boost the immune system
However multi vitamin and multi mineral supplements can boost immunity in elderly persons Nutritional Status
Substances that can significantly reduce immune function includes (a) Diet rich in saturated fat and animal protein (b) Using a lot of oil and fat in cooking (canola oil and olive oil are best for cooking) (c) Eating a lot of dairy products (d) Long term use of margarine (although can be unsaturated it is artificially prepared) Nutritional Status
Substances that improves the immune function includes – (a) Eating a balanced meal (b) Fermented diary products e.g. yogurt (c) Eating foods rich in antioxidants i.e. maintaining a steady vitamin and mineral intake …Vit. A, C, E (d) Taking in the required amount of micronutrients (e) Eating plenty fresh fruits and vegetables (f) Increase fibre intake (g) Drink plenty of water Exercise
Regular exercise helps to maintain a healthy immune system and mental health
Very prolonged bouts of exercise and periods of intensified training or competition are associated with increased risk of infection. Stress
Mood disorders can affect the immune system in a negative way
Symptoms such a fatigue, difficulties in memory and concentration, sleep disorder, aches and pains are common in persons with these disorders.