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Medical Immunology

Acquired Immunity

Medical Immunology

Harvesting Antibody

Medical Immunology: : Manufacturing Antibody

Monoclonal Antibodies

Medical Immunology: Manufacturing Antibody

Vaccines

Medical Immunology: Vaccines

Vaccination- The deliberate induction of adaptive immunity to a pathogen by injecting a vaccine, a dead or attenuated (nonpathogenic) form of the pathogen.

“Killed” vaccines* Bacterial Dead* Viral Replication Ability Removed

“Live” attenuated vaccines* Bacterial Nonpathogenic types or disabled mutants* Viral Reduced ability to replicate in human cells

More potent and risky for immunosuppressed individual

Requirements of Vaccines


* Safe

* Induce effective protection in a high proportion of the vaccinated population

* Long-lived immunological memory must be conferred

* There should be little or no requirement for “boosters”

* Cheap

An Effective Vaccination Program....


Provides “herd immunity”

By lowering the number of susceptible individuals in a population the natural reservoir of infected individuals also falls.

Thus the probability of transmission is reduced; even non-vaccinated individuals enjoy the benefits of a large scale vaccination program.

#*@%!

Allergies (Type 1 Hypersensitivity)

Medical Immunology: Allergies

Allergy- Disease following a response by the immune system to an otherwise harmless antigen

Common allergens* Drugs * Foods (eg. Tree nuts, shellfish)* Venoms * Insect bites * Pollens* Dust mites faeces

The antibody produced to respond to these antigens is IgE.

Allergies


The constant region of the IgE antibody may bind to surfaces of mast cells.

When allergens cross-link preformed IgE that is bound to mast cells histamine is released.

Histamine causes smooth muscle contraction and blood vessel dilation.

Allergy


Mast cells line the body surfaces (inc. blood vessels, connective tissue, lining of the gut and lungs) as an alert system to local infection.

As a result, an allergic reaction will create different symptoms depending on the tissue affected.

Blood Types: ABO

Blood Transfusions: ABO

Units of packed red cells are made by removing as much of the plasma as possible from whole blood units.

Thence, type O individuals are considered a universal donor- antibodies have been removed and no antigen is present to excite immune responses in the recipients.

Having both A and B antigen means that type AB individuals have no anti-A or anti-B antibodies. They are universal recipients.

Blood Transfusions: ABO and Rhesus +/-

The presence/absence of rhesus factor is marked by +/- respectively. Transfusions should approach rhess in the same manner as ABO.

Blood Typing: Rhesus Factor

Medical Immunology: Blood Typing

Immunodeficiency: HIV/AIDS

Medical Immunology: HIV/AIDS

First reported cases 1981

Over 25% of adults infected in Zimbabwe and Botswana

There are actually 2 types; HIV1 and HIV2

Spread to humans from primates

Pssst....wanna try some HIV1?

...how about some HIV2?

Human Immunodeficiency Virus


Infection occurs after transfer of body fluids via* infected T helper cells* as a free virus in blood, semen, vaginal fluid, milk

This includes:* Sexual intercourse* Sharing of contaminated needles* Use of infected blood or blood products* Pregnancy (25% foetal infection rate)

Human Immunodeficiency Virus


T helper cell populations are partially restored after an initial adaptive response.

Afterwards T helper cell populations will gradually and persistently decrease.

The destruction of T helper cells leads to immunodeficiency.

HIV is understood to primarily infect and replicate in T helper cells can also infect macrophages and dendritic cells.

T helper cell concentrations are significantly reduced after initial infection.

Acquired Immunodeficiency Syndrome (AIDS)


The adaptive immune response controls but does not eradicate HIV.

HIV does not immediately cause AIDS

Most infected individuals progress towards AIDS over time and die following opportunistic infections and tumours.

Tissue & Organ Grafting

Medical Immunology: Graft Rejection

This occurs as an immune response to antigens on the grafted tissue.

The tissues of donors and recipients must closely matched in order to minimise likelihood of rejection.

The likelihood of achieving a close tissue match therefore increases with greater genetic similiarity between donor and recipient.

Graft rejection involves the destruction of transplanted tissue

I prefer your head to mine.....

Hmmmm.......let's swap!!! (no-one will find out anyway!)

Donors and Recipients


There are several major categories of tissue grafting

Autografts: Donor and recipient are the same individual (often occurs for skin grafts)

Syngeneic grafts: Donor and recipient are identical (eg. identical twins)

Allografts: Donor and recipient are individuals of the same species

Xenografts: Donor and recipient are of different species

For recipients of allografts and xenografts a strict regimen of powerful immunosuppressant drugs is required.

MHC Matching


MHC markers are constantly presenting both self and non-self peptides on the membranes of nucleated cells.

Individuals with similar MHC types are likely to present a similar variety of peptides.

Thence matching MHC types is an important part of minimising the rejection of allografts.

Autoimmunity

Medical Immunology: Autoimmunity

Autoimmune diseases occur when an adaptive immune response is mounted against self antigens.

Because the antigen is part of the host's own tissues an immune response does not eradicate the antigen completely; resulting in a sustained immune response.

This can lead to chronic inflammatory injury to tissues.

Autoimmune disorders usually arise spontaneously and can be triggered by

* infectious agents* internal immune dysregulation

Autoimmune Diseases

Medical Immunology: Autoimmunity

Common autoimmune diseases include

Rheumatoid arthritisInsulin dependent diabetesMultiple SclerosisLupus ErythematosusPemphigus vulgaris

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