The start of Immunology… (Day 57)

Immunology Tube Agglutination test Seriology

Today I started the immunology section of the Microbiology module, rumours at the minute are that people on the 6 year course get to do this over 13 weeks whilst for us we have just 5 weeks which does demonstrate just how intense the course is. Personally I have already done a Immunology module in the past so I am pretty lucky with this just as a refresher (yay!) though I am trying to avoid getting exemption as its more challenging to do the exams as well!

So starting with the basics, immunology is the study of the immune system which is responsible for the bodys defences against disease and injury. It is split into two parts, the adaptive and the innate immune responses.

The innate immune system is most likely to be active at the sites that are the primary point of contact with the outside world. So for example the skin, respiratory tract, gastrointestinal tract, urogenital tract and the ocular mucosa. Each of these areas have special adaptions to prevent disease from entering the body, whether it is sebum and sweat (both contain anitmicrobials) which is secreted by the skin, or the cilia that lines the respiratory mucosa to transport foriegn particles upwards out of the lungs. In addition within the blood there are leucocytes such as neutrophils, macrophages, and natural killer cells that are continuously present which are ready to spring to defend against invaders. This response is relatively weak when compared to the adaptive immune response however can hold pathogens at bay for short periods of time. The innate immune system is also responsible for inflammation (which is indicated by the 5 cardinal signs: pain, swelling, heat, redness and loss of function) which help deal with the molecules released from dead or damaged cells.

The adaptive immune system however is stronger in being able to deal with pathogens, however it takes longer for the adaptive immune response to occur (usually 4 – 7 days). The adaptive immuned response is based around T lymphocytes (and the cytokine and chemokine messenger molecules) and the B lymphocytes which produce antibody. It also has a regulatory function to allow “switching off” after the pathogen has been destroyed so as not to damage the normal body tissues. Now this leads onto probably the most essential piece of knowledge, the adaptive immune system has memory, so when it encounters the same pathogen again the response is more effective and faster. This is why vaccination works, vaccination adds the pathogen into the memory bank of the immune system allowing it to deal with it before it gets a hold if it is ever encountered later on. This phenomenon is known as the secondary immune response.

When thinking about the different immune responses it can be likened to a an army patrol (the innate immune system) coming across the enemy when on patrol and sending for help from the main army base (the adaptive immune system) which then turns up to win the war.

Anyways back to the actual practical session, today we looked different methods of testing for disease through blood serum antigen (immune response causing particles) and antibodies (markers that attach to antigens) levels. One of the most valuable tests within seriology is the determination of how bad the disease actually is, and whether it is acute or chronic. This is done by a simple agglutination test either in a test tube, on a microscope slide or with a commercial kit.

Immunology Tube Agglutination test SeriologyUsing this test a serum sample is mixed with a solution that contains the associated antibodies or antigens for what is being tested. If it is a positive test the antibodies will bind to the antigens and form clumps (agglutinate).

Anyways enough for today! I’ve got to get back to Latin, until tommorow! Thank you to everyone that has supported me, even a £1 really does help and you can do it securely on the right of this page!