Acquired Immunity and Adverse Affects Associated with Immunity

Acquired Immunity and Adverse Affects Associated with Immunity

Acquiring Specific Immunity Active Immunity • A person must first come in contact with a pathogen to then make antibodies. • These antibodies then make a person resistant to the infection if it were to invade again. – Antibodies are acquired, therefore it is also called Acquired Immunity Passive Immunity • Antibodies are received from an outside source

Active Immunity • Production of antibodies within a person in response to exposure to a particular antigen. • Also: – B memory cells and T cells are produced and react quickly if pathogen invades again. • But there are two types of active immunity – Natural – Induced

Natural Active Immunity • Person comes in contact with pathogen – No antibodies present – Takes a few days for plasma cells and antibodies to form (symptoms of disease may show) • As antibodies increase, infecting pathogen begins to be destroyed. • Person will recover if sufficient antibodies are made to completely destroy pathogen. • Person now has self made antibodies specific for that pathogen if it were to invade again.

Induced Active Immunity • Vaccines that contain dead or treated living microbes are used to activate the immune system to produce antibodies without actually causing the disease – The bacteria or viruses are killed or treated in some way (attenuated) to stop causing disease but to minimise damage to their antigens. – A persons immune system still recognises it as nonself and so makes specific antibodies for it. – If a person comes in contact with the actual pathogen antibodies and memory cells are ready to defend.

Brief How Are Vaccines Made

1 st vaccine + booster required for immunity

Eradicating disease • Small Pox – World Health Organisation (WHO) began an extensive vaccination program against small pox in 1959. – Vaccinations were conducted worldwide – The aim was to stop the virus being able to find any host it could survive in and reproduce. – By 1979 the disease had been eradicated – Australians do not have to be vaccinated against small pox because it does not exist in Australia. • For modern day diseases, parents who do not choosing to vaccinate children are providing hosts for these pathogens to continue to inhabit

With acquired immunity, why do we still get colds and flus every year? • Viruses are continually changing – Specifically, the antigens are changing shape – This means the body has not detected this type of antigen before and so does not have the immunological memory to deal with it. • 1918 -1919 influenza pandemic – Most people who died were young adults • Weird – Old people may have survived because they had been exposed to a similar virus when they were younger and so had antibodies to that strain.

Passive Immunity • Antibodies are not made by the person, but introduced to their bodies and yet are active against the pathogens. – Antibodies may be produced in one person and introduced to another person. – Will provide protection straight away, but only lasts for a few weeks. • Two types of passive – Natural – induced

Natural Passive Immunity • Developing fetus receives maternal antibodies across the placenta. – Important because Babies immune system doesn’t mature until after birth • Baby acquires antibodies through the mothers milk. – Colostrum (thick yellowish milk) produced during the first two or three days after birth is rich in antibodies.

Induced Passive Immunity • Injection of antibodies – Obtained from blood collected from voluntary donors by the Australian red cross society. – Antibodies are extracted from the blood plasma of a person known to have a disease (eg hep A)

Adverse Affects of the Immune System • Allergies – Histamines cause contraction of smooth muscle in tubules leading to lungs – difficulty breathing • Autoimmune disease – Multiple sclerosis (detects myelin sheath as antigens) – Transplanted organs – Rheumatoid arthritis (detects collagen in joints as antigens)

Rhesus Compatibility • Rhesus+ child in Rhesus– mother; • During birth mothers blood comes in contact with childs…mother creates antibodies to childs blood. • When mother has second Rhesus + child, she may pass some of these antibodies through the placenta – Antibodies react with babies blood type and tissue damage can occur • Treatment can be given to mothers after the first birth by injecting antibodies to get rid of the babies Rhesus + cells and prevent the mother from creating her own antibodies and memory cells.